Sealant container

Abstract

A sealant cartridge housing 200 comprises a housing tube 201 and a slider 202, the slider being slidably received within the housing tube 201, and slidable along the length of the housing tube when a

Description

This invention relates to reducing the amount of plastic waste generated by the use of sealant guns to apply sealant. Sealant applicators, commonly referred to as sealant guns or caulking guns, are widely used both in the building trade and kitchen or bathroom installation trade, and in do-it-yourself (DIY) home improvement schemes. It will be appreciated that “sealant” is used herein as a general term to cover sealants (e.g. silicone sealant), caulks, fillers (e.g. wood fillers) and similar materials which are applied in a paste-like form and then dried, hardened, or otherwise set so as to fill or seal gaps, smooth edges, and similar, in building work, kitchen and bathroom fittings, DIY and craft projects, and the like. Sealant guns comprise a substantially cylindrical body, a piston or plunger arranged to move from the back of the cylindrical body towards the front, and a handle with a trigger, generally arranged towards the rear of the cylindrical body, arranged to allow a user to move the piston forwards. A release mechanism to allow the piston to be returned rearward is generally also provided. Sealant guns are generally made of a combination of plastic and metal but may be all-metal or all-plastic in some examples. The cylindrical body may be solid-walled or open-sided with rings / struts defining the cylindrical shape. Open-sided bodies are generally more common due to the reduced material cost. The cylindrical body is arranged to receive a container of a sealant. These containers are generally single-use, as in many cases they are not re-sealable, and cleaning them would generally be uneconomical. Further, once the containers are opened, the sealant within may gradually start to dry out / set, so limiting the container’s useable lifespan from first usage. Containers come in different standard forms - rigid-walled plastic cylinders with moveable bases (“cartridges”), and sausage-like foil-wrapped cylinders of sealant (“foils”), generally with a metal pin at each end (although crimping or another sealing means may be used in other examples). In principle, foils are best from an environmental perspective due to the huge reduction in plastic waste - the foil can be compressed to a tiny “puck” of material once empty, the foil often being a multi-layer polymeric and aluminium-based skin around the sealant, whereas each sealant cartridge represents a much larger amount of single-use material. Open-sided guns can be used for sealant cartridges, whereas solid-walled guns are needed for foils, to support the otherwise non-rigid “sausage” of sealant. The need for a solid-walled gun. and the difficulty in exchanging one partially-used foil for a new foil when a different sealant is needed, have limited the uptake of sealant foils despite the reduced waste. If the container comprises its own nozzle, no nozzle need be provided with the gun. If the container does not comprise, or have associated therewith, its own nozzle, a nozzle is provided with, or as part of, the gun. Cartridges generally comprise their own nozzle, or at least a partial, threaded, nozzle to which an attachment can be connected; foils do not. Cartridges therefore comprise a significant amount of plastic - both for their rigid walls and for their nozzles - and this plastic is single-use. It is estimated that over 100 million cartridges end up in landfill each year. This is therefore a large volume of plastic waste. Geocel® offers an ecoSEAL system comprising reusable “cartridge sleeves” which can be inserted into a standard open-walled sealant gun and used to support a foil of sealant inside, so encouraging the uptake of use of less wasteful foils rather than solid cartridges. The user cuts or otherwise pierces the foil and inserts it into the reusable sleeve. These sleeves can have a nozzle attached to guide sealant. However, it has been found that users often throw away the ecoSEAL product in preference to cleaning it after use, so plastic waste has not decreased as much as hoped. In addition, the ecoSEAL tubes are limited to certain foil sizes, so not able to accept 400 mm long foils, for example, and have the same drawback as for traditional foil guns that a partially-used (and so opened and vulnerable to leakage) foil must be removed, suitably stored, and later replaced if switching between different materials over the course of a job. As such, trade users have generally not seen sufficient benefit over a more traditional foil gun and uptake of the product has been limited. According to a first aspect of the invention, there is provided a sealant cartridge housing comprising: a housing tube arranged to receive a sealant foil therewithin; a nozzle on the front end of the housing tube, the nozzle comprising a nozzle outlet extending forward of the housing tube, and wherein the sealant cartridge housing further comprises a foil-breaching means within the housing tube. The foil is therefore automatically opened to provide the sealant when the sealant gun is used - there is no need to cut off a front nozzle portion (as for prior art cartridges), nor to cut or otherwise pierce a foil before inserting it into a sleeve or gun. The foilbreaching means serves to open the foil automatically as the foil is pushed forward in use. Ease of use is therefore improved, and, as the foil is contained within a housing tube, partially-used foils can be switched in and out of the gun with the same ease as prior art cartridges. The foil-breaching means is arranged to cut, pierce, or otherwise breach a forward end of the foil as it is pushed towards the nozzle in use, and may be described as a foilpiercer or foil cutter. The foil-breaching means may be or comprise a spike or cutting edge facing rearwardly. The foil-breaching means may be a part of the nozzle - i.e. the nozzle may comprise the foil-breaching means. Alternatively or additionally, the foil-breaching means may be provided by a part of, or mounted on, the housing tube. The foil-breaching means may be or comprise a spike extending rearwardly within the housing tube. Alternatively or additionally, the foil-breaching means may be or comprise a cutting wire (e.g. extending across all or part of a diameter of the housing tube), or a blade (e.g. a razor-type blade extending across all or part of a diameter of the housing tube, or an angled blade). The nozzle may comprise a cup extending rearwardly within the housing tube, wherein the nozzle outlet comprises a channel passing through a base of the cup. Dried-on sealant can inhibit recycling of the housing tube even if made from recyclable plastics or cardboard; the use of a cup may assist in containing and directing the sealant, so reducing or avoiding sealant contamination of the housing tube. In embodiments with a cup, the foil-breaching means may be or comprise a spike extending rearwardly within the cup. Alternatively or additionally, the foil-breaching means may be or comprise a cutting wire (e.g. extending across all or part of a diameter of the cup), or a blade (e.g. a razor-type blade extending across all or part of a diameter of the cup, or an angled blade). In use, a sealant foil is provided within the sealant cartridge housing, so forming a sealant cartridge. The spike, or other foil-piercing or foil-cutting means, is arranged to pierce the foil so as to release the sealant when a force is applied (e.g. by moving a plunger of a sealant cartridge gun forward, pushing a front end of the foil towards and against the nozzle). An intact foil can therefore be placed within the housing tube, and pierced in situ - no preparation step of cutting the foil is therefore needed, so the sealant cartridge can be used as a direct replacement for known sealant cartridges, with no difference in user actions required, so encouraging and facilitating uptake. In addition, the need to cut off or otherwise remove the end of prior art sealant cartridges may be obviated, so making use of cartridges as described herein easier than use of prior art cartridges, as well as optionally being more environmcntally-friendly. The spike, or other foil-breaching means, is generally arranged at least partially within the cup (where present) - for example extending rearwardly within the cup, or extending across a portion of the cup. In general, it may be preferable for the foilbreaching means not to extend rearwardly beyond a rearmost edge of the cup so as to reduce the likelihood of sealant escaping into the housing outside of the cup. Below, the term “spike” is used for brevity, but it will be appreciated that any suitable foil-breaching means may be used. The foil-breaching means may be referred to as a foil-piercer, foil-tearer, or foil-cutter. Any means suitable for physically making a hole in the foil may be used as the foil-breaching means, with a simple mechanical interaction with one or more sharp edges or points being favoured. When a sealant foil is placed within the housing tube, a sealant cartridge is therefore formed. The sealant cartridge may be sold in this state - i.e. filled. The sealant cartridge can be mounted within a standard sealant gun. When a plunger of the sealant gun is moved forward, the foil is pushed forward and onto the spike. The spike then pierces the foil to release the sealant, which can then pass through the nozzle outlet. There is therefore no need to pierce the foil before it is inserted into the housing tube, so allowing a sealant cartridge containing a foil to be provided to a user, and handled as a user normally would handle a prior art sealant cartridge - for example being used with an open-walled gun, and switching cartridges in and out in use. In embodiments with a cup, when a plunger of the sealant gun is moved forward, the foil is pushed into the cup and onto the spike. The spike pierces the foil to release the sealant, which can then pass through the nozzle outlet. As the spike is generally within the cup, and the cup holds a front end of the sealant foil, any unused ejected sealant is generally retained within the nozzle and foil and should not touch the housing tube. The housing tube therefore generally remains clean and can be easily detached and recycled, with only the nozzle and foil being thrown away after use. The amount of landfill waste can therefore be significantly reduced, depending on material choices. The housing tube is arranged to receive the sealant foil in that it is sized and shaped to accommodate a sealant foil in a particular position - sealant foils are generally sausage-shaped, so the housing tube is generally hollow and cylindrical, with a length larger than or equal to that of the foil, and an internal diameter equal to or slightly larger than the external diameter of the foil, such that the foil can be received within the tube along the tube’s axis, but cannot move significantly off-axis. The foil is therefore necessarily oriented lengthwise within the housing tube, parallel to the length of the tube. The housing tube may be sized and shaped to be large enough to receive the largest widely-used foil, or different housing tubes may be made for different foils. The cup (where present) may help to guide the forward end of the foil into position. It will be appreciated that whilst the sealant cartridge housing may be sold as-is to a foil manufacturer or trade supplier (for example), the sealant cartridge housing may generally be assembled with a foil before it reaches an end user - the housing design may therefore be specific to a certain foil shape / size. The housing tube may be provided with a slider, optionally in the form of a disc, the slider being slidably received within the housing tube, and slidable along the length of the housing tube when a force is applied to the slider. It will be appreciated that users sometimes change cartridges or foils during a job (e.g. for different colours or types of sealant), and then change back to the previous (unfinished) cartridge or foil; the slider may serve to keep the foil in place while the cartridge is not in the gun. Especially in embodiments in which the slider is in the form of a disc, one or more ribs, or other slider-stops or disc-stops, may be provided within, or as part of, the housing tube to retain the disc within the housing tube. For example, the housing tube may comprise a disc-stop in the region of its rear end, the disc-stop being arranged to retain the disc within the housing tube. The disc-stop may be or comprise a circumferential rib. In some embodiments, especially in embodiments with sliders of different shapes, for example hollow cylindrical sliders capped at a forward end only, sufficient friction may be present between the slider and the housing tube without a need for stops to keep the slider in place under the weight of the foil. In some embodiments, all components of the sealant cartridge housing may be at least one of recyclable and compostable. In other embodiments, the nozzle may be the only non-recyclable or non-compostable component of the sealant cartridge housing. For example, the housing tube (and slider where present) may be made of cardboard, whilst the nozzle may be made of plastic (which may or may not be a recyclable or compostable plastic). The spike is arranged to provide at least one cutting edge or point to pierce or cut the foil “skin” of a sealant-containing foil. Multiple spikes, or an extended cutting edge from a single spike, may be provided to facilitate sufficient opening of the foil for sealant expulsion. In embodiments with a cup, the spike, or all spikes in embodiments with multiple spikes, may have a rearward extent of no more than that of the cup, such that they are located fully within the cup. The spike, or at least one spike of a plurality of spikes, may extend rearwardly beyond the cup in other embodiments, such that the spike extends rearwardly beyond the rearward extent of the cup. It will be appreciated that dimensions of the nozzle, including positioning and shaping of the cup (where present) and spike(s) (where spikes are a part of the nozzle), may be adjusted as appropriate to fit different sealant foils. The nozzle may therefore be manufactured for a specific foil dimension, as there is not a single standard and this varies from manufacturer to manufacturer. It will be appreciated that nozzle shape and size may generally be independent of foil length, but affected by foil diameter as the cup is generally arranged to be able to receive a front portion of the foil. As the sealant is used up, the foil and remaining sealant therewithin may be compressed into a disc or puck at least partially within the cup. The housing tube, and optionally also the slider, may be made of cardboard. The sealant cartridge housing, and more specifically the nozzle of the sealant cartridge housing in many embodiments, may comprise a plurality of spikes extending rearwardly. The spikes of such embodiments may be arranged in a ring around the nozzle outlet channel, and within the cup where present. At least six spikes may be provided. The spikes may be evenly spaced around the ring. Alternatively, a larger gap may be left between spikes around one portion of the ring’s circumference to provide a larger reason in which the foil is not pierced - this may reduce the risk of a portion of the foil becoming detached in use. The or each spike may be oriented parallel to the length of the tube, and may comprise a rearward cutting edge or point. The housing tube may have an outer diameter of 40-60 mm, and optionally of 45-50 mm. The housing tube may have a length of 150-400 mm, and optionally of 200-325 mm. It will be appreciated that dimensions of the housing tube may be selected as appropriate to fit a particular type / size of sealant foil. The nozzle may comprise a cap arranged to be seated on the front end of the housing tube. The nozzle outlet channel may widen within the cap, from a first diameter at a rearward end of the protruding nozzle outlet / at a forward face of the cap to a second, larger, diameter at a rearward face of the cap. In embodiments with a cup, the base of the cup may be provided by the cap. The cap may lie between the cup and the nozzle outlet, with the nozzle outlet channel passing therethrough, so fluidly linking the inside of the cup to the nozzle outlet. The nozzle outlet channel may widen within the cap, from a first diameter at a rearward end of the nozzle outlet to a second, larger, diameter at a rearward edge of the cap. The nozzle may comprise a wall. The wall may extend around a circumference of the nozzle outlet channel - optionally the wall may enclose a region of larger crosssection than the nozzle outlet channel, such that there is a radial spacing between the nozzle outlet channel and the wall. The wall may enclose a region with a width of at least 150% the width of the nozzle outlet channel. In embodiments with a cup, the wall may extend within the cup / the cup may surround the wall. The sealant cartridge housing, and more specifically the nozzle, may comprise a single spike. The wall may be, or may be a part of, the spike. The wall may be cylindrical such that the spike comprises a tube encircling the nozzle outlet. The tube of the spike may have a greater cross-sectional width than the nozzle outlet channel, optionally having a diameter of at least 150% of the diameter of the nozzle outlet channel. The tube of the spike may comprise an angled rearward end, the point of the angled rearward end of the tube of the spike providing a piercing edge. The tube of the spike may have a sharpened wall edge towards its point, and a relatively smoother wall edge away from its point. The spike may comprise a pointed protrusion, or tooth, extending rearwardly from a rearmost part of the tube. Multiple teeth may be provided in some embodiments. The tube of the spike may comprise a notch extending forwardly, the notch optionally being smooth. The notch may be diametrically opposite a piercing edge or point of the spike. Multiple notches may be provided in some embodiments. The sealant cartridge housing may comprise an elongate barrier (e.g. a cross-bar within the cup), extending across a portion of the housing tube. The barrier may be provided by a strut extending from and across the cup or housing tube, or by a strut extending from and across a tubular wall of a spike, or, in an embodiment with multiple spikes, by a strut extending from and between spikes (extending from a point on each spike forward of its rearward cutting edge / tip, e.g. half way up the spikes). In other embodiments, the barrier may be mounted on the housing tube. The barrier may assist in holding back a ripped / opened portion of the foil whilst allowing the sealant to reach the nozzle outlet. The cup, where present, may have a rearward extent of at least 20% of the diameter of the housing tube, and optionally of at least 30%, 40%, 50%, or 60% of the diameter of the housing tube. According to a second aspect, there is provided a nozzle for a sealant cartridge housing, the nozzle comprising: a nozzle outlet comprising a channel; and a spike or cutting edge facing rearwardly. The spike or cutting edge is arranged such that a foil approaching the nozzle from behind is cut, torn, or pierced (i.e. breached) as it approaches. The spike or cutting edge may therefore be referred to as a foil-breaching means. The nozzle may further comprise a cup extending rearwardly behind the nozzle outlet, and wherein the nozzle outlet channel is arranged to pass through a base of the cup. In some embodiments, the nozzle may comprise a spike extending rearwardly within the cup, and / or a blade or other cutting edge extending across at least a portion of the cup, such that a foil approaching the cup from behind is cut, torn, or pierced (i.e. breached) as it approaches. The cup may be arranged to receive a forward end of a sealant foil in use. The nozzle may be as described with respect to the first aspect, and may be used as a part of the apparatus of the first aspect. According to a third aspect, there is provided a sealant cartridge comprising a sealant cartridge housing as described with respect to the first aspect, and a sealant-filled foil mounted within the housing tube. As the sealant-filled foil is contained within the housing tube, the cartridge may look like, and be used equivalently to, a prior art sealant cartridge. According to a fourth aspect, there is provided a sealant applicator comprising: a sealant gun comprising a body and a plunger arranged to move along the body; a housing tube arranged to fit slidingly within the gun body, and to slidingly receive the plunger; a sealant-filled foil mounted within the tube; and a nozzle mounted on the front of the tube, the nozzle comprising a nozzle outlet extending forward of the housing tube, the sealant applicator further comprising a foil-breaching means located within the housing tube and arranged to breach the foil. The sealant gun is arranged such that the foil is pushed forward as the plunger moves forward. The foil-breaching means makes a hole in the foil as the foil is pushed onto it. The sealant is thereby ejected from the foil, passing through the breach in the foil to the nozzle, and thereby is ejected from the sealant applicator. For the example of a spike, as the spike pierces the foil, the sealant is then ejected from the foil as the plunger continues to move forward. The spike makes a hole, or piercing, in the foil and the sealant is ejected from the foil through the hole in the foil, and is forced forward into and through an outlet of the nozzle. It will be appreciated that the equivalent process applies for other forms of foil breachers, such as cutting edges. The nozzle may comprise a cup extending rearwardly within the housing tube and arranged to receive a front end of the foil. The housing tube may be made of cardboard. A flat sheet of cardboard, or other material, may be rolled or otherwise shaped to form the tube - volume for shipping of components may thereby be reduced as compared to shipping tubes. The housing tube may have a slider towards the rear of the housing tube, the slider being arranged to contact the plunger. The slider may be made of cardboard. The slider may serve to retain the foil within the housing tube. The nozzle may be made of plastic. The tube and nozzle together, optionally with the slider, may form the sealant cartridge housing of the first aspect. According to a fifth aspect, there is provided kit of parts for a sealant applicator, comprising: the sealant cartridge housing of the first aspect; a sealant-filled foil arranged to be mounted, or already mounted, within the sealant cartridge housing; and a sealant gun arranged to receive the sealant cartridge housing. The kit of parts may comprise multiple sealant cartridges in accordance with the third aspect. The skilled person will appreciate that features discussed in relation to any one aspect of the invention may be provided with any other aspect of the invention, mutatis mutandis. Embodiments of the invention will now be described in more detail by way of example only with reference to the accompanying drawings in which like or corresponding reference numerals are used for like or corresponding features: Figure 1 is a side view of a sealant gun and cartridge; Figure 2 is an exploded perspective view of a cartridge housing; Figure 3 is an exploded perspective view of a cartridge, including the cartridge housing of Figure 2 and a sealant foil; Figure 4 is a further exploded perspective view of the cartridge housing of Figures 2 and 3; Figure 5 is a further exploded perspective view of the cartridge housing of Figures 2 and 3; Figure 6 is a side view of a nozzle of the cartridge housing; Figure 7 is a perspective view of the nozzle, with hidden components shown in broken lines; Figure 8 is a top view of the nozzle; Figure 9 is a sectional view of the nozzle, taken on the line marked A-A in Figure 10 is a side view of a second nozzle for a cartridge housing, with a screw-threaded outlet; Figure 11 is a sectional view of the nozzle of Figure 10, taken in the same place as for the sectional view of Figure 9; Figure 12 is a perspective view of the nozzle of Figure 10, with hidden components shown in broken lines; Figure 13 is a perspective view of the nozzle of Figure 10, with part of the cup cut away; Figure 14 is a side view of a cartridge housing including the nozzle of Figure 10; Figure 15 is an exploded perspective view of the cartridge housing of Figure 1; Figure 16 is a perspective view of an alternative nozzle from that shown in Figure 10, with part of the cup cut away; Figure 17 is a rear view of the tube of Figure 1; Figure 18 is a cross-sectional side view of the tube of Figure 1, with dimensions labelled for clarity, taken along the line G-G marked in Figure 17; Figure 19 is a rear end view of a disc similar to that of Figure 1; Figure 20 is side view of the disc of Figure 19; Figure 21 is a perspective view of an alternative nozzle from those shown in Figures 10 and 16; Figure 22 is a side view of the nozzle of Figure 21; Figure 23 is a rear end view of the nozzle of Figures 20 and 21; Figure 24 is a cross-sectional side view of the nozzle of Figures 20 and 21, taken along the line G-G marked in Figure 23, with dimensions marked; Figure 25 is an enlarged version of Figure 24, with dimension markings removed, rotated to match the orientation of Figure 22; and Figure 26 provides cross-sectional side views of housing tube portions with two different sliders. Figure 1 illustrates a sealant applicator 1 comprising a sealant gun 100 and a sealant cartridge 300 mounted on the gun. The sealant gun 100 comprises a cylindrical body 102. The cylindrical body 102 is open-walled in the example shown, with a plurality of struts defining the cylindrical shape. A rib 102a extends around a forward part of the cylindrical body 102, extending radially inward around the circumference, and may therefore be described as a circumferential rib 102a. The sealant gun 100 further comprises a plunger 104 arranged to move along the body 102, the plunger 104 comprising a plunger disc 106 at a forward end of the plunger 104. The sealant gun 100 further comprises a handle 108 comprising a “trigger” or actuator. The handle 108 is arranged to be held by a user, and the two parts of the handle 108 to be squeezed together to move the plunger disc 106 forward. It will be appreciated that the handle / trigger design 108 shown is provided by way of example only and that different actuation means - e.g. a screw mechanism - may be used in other examples. The sealant gun 100 may comprise a ratchet mechanism arranged to prevent rearward slippage of the plunger 104 unless it is deliberately released by a user, in some implementations. The sealant cartridge 300 is substantially cylindrical in shape, and sized to fit within the cylindrical body 102 of the gun 100. The sealant cartridge 100 is a sliding fit within the cylindrical body 102 in the example shown. The sealant cartridge 300 comprises a nozzle outlet 206 extending from its front face. The nozzle outlet 206 is arranged to extend forward of the front of the sealant gun 100 in use. The rib 102a of the sealant gun 100 is sized and shaped to prevent further forward motion of the sealant cartridge 300 within the gun 100, whilst allowing the nozzle outlet 206 to extend out of the cylindrical body 102 of the gun 100. The rib 102a narrows the opening at the front of the sealant gun 100 to less than the diameter of the sealant cartridge 300, so preventing further relative movement of the cartridge 200. The circumferential rib 102a may be replaced with a barrier of a different form -e.g. one or more struts - in other examples. The circumferential rib 102a, or other barrier, may be detachable form the rest of the gun 100 so as to facilitate insertion of the cartridge 200, and may then be reattached to secure the cartridge 200 within the body 102 in some embodiments. In other embodiments, the cartridge 100 may be inserted from the rear end of the cylindrical body 102, or from the side. The body 102 of the gun is described as cylindrical due to being arranged to receive a cylindrical cartridge 300, and generally taking a cylindrical form accordingly for ease of manufacture without excessive material use. However, it will be appreciated that the external shape of the body 102 is not critical to its function, and that the body 102 may be for example square or rectangular in external cross-section in some implementations. The cartridge 300 comprises a housing tube 201 arranged to fit slidingly within the gun’s body 102. The cartridge 300 of Figure 3 further comprises a slider 202 in the form of a disc 202 towards the rear of the housing tube 201, the disc being arranged to contact the plunger disc 106 in use, and to be pushed along the housing tube 201 when a force is exerted via the plunger 104. The housing tube 201 of various implementations includes a disc-stop 201a or barrier, arranged to prevent the disc 202 from leaving the housing tube 201. The disc 202 may be thought of as forming a part of the housing tube 201 - more specifically, being a moveable, rearward, closure for the tube. The disc-stop 201a is located at or near a rearward end of the cartridge 200. In the example shown, the disc-stop 201a is in the form of a rib 201a extending radially inwardly around the circumference of the housing tube 201. The disc-stop 201a is arranged to allow the plunger disc 106 to enter the cartridge 200 and push the disc 202 of the cartridge forward. An inner diameter of the disc-stop 201a is therefore greater than the diameter of the plunger disc 106 but less than the diameter of the housing disc 202. The housing disc 202 therefore has a greater diameter than the plunger disc 106. The housing disc 202 may be sized to be a tight sliding fit with the housing tube 201, and may have a sufficient depth (parallel to tube length) to prevent rotation of the housing disc 202 within the housing tube 201. In some examples, multiple ribs may be provided within the housing tube 201, optionally similar to the disc-stop rib 201a shown near the rear end of the tube, but further forward. For example, a rib may be provided every 10 mm-20 mm along the housing tube’s length. These ribs (not shown) may be used to prevent the disc 202 from falling all the way to the end of the housing tube 201 when the cartridge 300 is removed from the gun 100 (or the plunger disc 106 retracted); the disc 202 may be retained by the closest rib. In use, the disc 202 would be pushed past the ribs when the gun 100 is used, and when the pressure is relieved from the plunger 104, or the cartridge 300 removed from the gun 100 altogether, the closest rib would retain the disc 202 and stop the foil 2 from moving away from the nozzle 203. In other implementations - for example in implementations in which the friction of the disc 202 on the inner wall of the housing tube 201 is sufficient to keep the disc in place -no such ribs may be provided. The cartridge 300 further comprises a nozzle 203 mounted on a forward end of the housing tube 201. The nozzle 203 provides the nozzle outlet 206 and a front face of the cartridge 300. The housing tube 201, housing disc 202, and nozzle 203 may together be described as forming a housing 200 of the sealant cartridge 300, i.e. a sealant cartridge housing 200. In some embodiments, no disc or other slider 202 may be provided - however, a housing disc / slider 202 may facilitate retention of the foil within the cartridge 300 without impeding plunger access and may therefore generally be favoured. The sealant cartridge 300 further comprises a sealant-filled foil 2, housed within the sealant cartridge housing 200. The sealant-filled foil 2 is generally substantially cylindrical in shape, with curved ends, and is sometimes referred to as a “sealant sausage” due to this sausage-like shape. The foil forms a skin around the sealant contained therewithin. The foil 2 is generally crimped or sealed with metal staples / clips 2a at each end. The foil 2 fits within the housing tube 201, with its length aligned with the housing tube’s length. In use, the nozzle 203 is located in front of the sealant-filled foil 2, and the housing disc 202 is behind the sealant-filled foil 2. The housing tube 201, together with the shape of the foil “skin”, generally prevents or limits radially outward movement of the sealant. Forward movement of the plunger 104 therefore compresses the foil 2, forcing the sealant contained within the sealant foil 2 out through the nozzle outlet 206. The nozzle 203 may be mounted on the front of the housing tube 201, or may be formed integrally with the housing tube 201 in some implementations. The nozzle 203 comprises a cap 208 arranged to effectively form a front face of the housing tube 201. This front face 208 may make contact with the rib 102a of the gun 100, so preventing further forward movement of the cartridge 300 within the gun 100. The cap 208 is substantially disc-shaped in the implementation shown, and may be a tight, sliding, fit within the housing tube 201. The nozzle 203 is connected to the housing tube 201 by its front face 208 in the implementation shown, although it will be appreciated that the nozzle 203 may be differently connected to the housing tube 201 in other implementations. The front face part / cap 208 of the nozzle 203 is substantially discshaped, in the examples shown, with the nozzle outlet channel 206a passing therethrough. The diameter, Dcap, of the cap 208 at the cap’s front face may be equal to (or slightly greater than) the outer diameter of the housing tube 201. The cap 208 may have a slightly narrower rearward portion 208b with a diameter arranged to fit slidingly within the housing tube 201, so providing a rim or lip arranged to seat the cap 208 securely at the front of the tube 201. In the examples shown in the figures, the cap 208 has a plurality of short ribs 208a (in the examples shown, four such ribs) spaced evenly around the disc’s circumference and extending the depth of the narrower portion of the disc 208 / along the length of the housing tube 201 in use. These ribs 208a may assist in holding the housing tube 201 to the nozzle 203, by friction. The ribs 208a may have a thickness at least substantially equal to the difference in radius between the front face of the cap 208 and the rear, narrower, portion of the cap 208. The housing tube 201 may deform a little to accommodate the ribs 208a, and / or may comprise indentations into which they fit engagingly. Other means of securement may be used, additionally or alternatively, in other examples. Adhesive or staples may be used in some examples, although it will be appreciated that separability of the nozzle 203 from the tube 201 may be desirable for disposal / recycling. The nozzle outlet 206 extends forward of the front face part 208. The nozzle outlet 206 extends forward of the housing tube 201, and forward of the front face 208. The cap 208, which is arranged to be seated on the front end of the housing tube 201 in use, comprises a rearward part of the nozzle outlet channel 206a. In some embodiments, the channel 206a is of constant diameter - in other embodiments, it may change in diameter, and / or in shape, within the cap 208, for example widening from a first diameter at a rearward end of the nozzle outlet to a second, larger, diameter at a rearward edge of the cap. The nozzle 203 further comprises a cup 204 extending rearwardly within the housing tube 201. A base of the cup 204 is provided by a rearward surface of the cap 208. The cup 204 surrounds / encloses the nozzle outlet channel 206a. The cup 204 widens as it extends rearwardly within the housing tube 201. The cup 204 may contact the inner surface of the housing tube 201 at the cup’s widest extent. The cup 204 is arranged to receive a forward end of the sealant foil 2, and to direct the sealant expelled from the foil towards the nozzle outlet 206 in use. The nozzle 203 further comprises at least one spike 210 arranged to cut or pierce the foil 2. The or each spike 210 has an at least substantially rearward-facing cutting edge or piercing point, and is arranged to cut or pierce the sealant foil 2 as the plunger 104 pushes the rear end of the foil 2 forward within the cartridge 300. The spike 210 may provide a defined point at which the foil 2 is breached. The size, shape, and position of the spike 210 may be selected based on foil dimensions and properties so as to provide a hole in the foil 2 at a desired location and of a desired size, such that the sealant within the foil is released in a desired direction. Similarly, if a plurality of spikes, or a different form of foil-breaching means, is used, the size(s), shape(s) and position(s) may be carefully controlled to provide a desired breach in the foil 2. In particular, the foil-breaching means 210 may be arranged to provide a hole only in the forward end of the sausage-shaped foil, without significant tearing along its length. The or each spike 210 extends rearwardly within the housing tube 201 so as to facilitate this cutting of the foil 2. The or each spike 210 lies radially within the cup 204 in the examples shown such that the hole(s) in the foil 2 are contained within the cup in use, reducing the chance of the expelled sealant escaping around the edges of the cup 204 and coming into contact with the housing tube 201. As the plunger 104 pushes the rear end of the foil 2 forward within the cartridge 300, the foil 2 is compressed, forcing the sealant out of the foil 2, via the hole(s) in the foil formed by the spike(s) 210, and through the nozzle outlet 206 - more specifically through a channel 206a which passes through the base of the “cup” 204 and forwardly out of the nozzle 203. The foil material itself is retained within the housing tube 201, eventually forming a “puck” sandwiched between the base of the cup 204 and the disc 202 when the plunger 104 reaches its forward-most position. It will be appreciated that the sealant material is generally sticky and may not all be ejected from the foil 2 - the “puck” therefore comprises the foil material and any remaining sealant. If the foil 2 is only partially used, a larger amount of sealant may remain within the foil. The cartridge 300 may be re-sealed in such cases, for example with a screw-fit or push-fit cap being placed over the nozzle outlet 206. Figure 10 shows an example of a nozzle outlet 206 with an external screw thread 206b arranged to receive a threaded cap and / or a threaded shaped outlet piece for sealant application. It will be appreciated that, once the foil 2 has been pierced, the sealant is no longer in airtight conditions and is likely to set / harden over time even with a cap in place. The puck, or larger remaining part of the partially-used foil 2, may therefore end up adhered to the nozzle 203 if the nozzle is not promptly cleaned. The nozzle 203 may be disposed of with the remainder of the foil 2. This combination is unlikely to be recyclable or compostable, and so may go to landfill. However, the cup 204 shields the housing tube 201 from the sealant, so the housing 201 and disc 202 may be easily-removed / separated from the nozzle 203 and used foil 2. This may facilitate the separation of parts for re-use, recycling, or composting. For example, at least the housing tube 201 and disc 202 may be made of cardboard, which may be composted or recycled, hemp board, or another compostable material. Recyclable, and optionally also already recycled, plastic may also be used. The nozzle 203 may be made of the same material(s) as the housing tube 201, or of a different material. It will be appreciated that the material property requirements may be stricter for the nozzle 203 than for other components of the cartridge housing 200. In particular, the nozzle 203 must withstand the pressure being applied by the plunger 104, and the pressure of the sealant being forced through the nozzle channel 206a, without any significant deformation, and in many embodiments also provides a spike 210 strong and sharp enough to pierce the foil 2. By contrast the housing tube 201 does not experience much compression, as the plunger disc 106 passes within the housing tube 201, and does not experience much outward pressure, if any, as the walls of the foil 2 and the cup 204 generally retain the sealant within their radius. Similarly, the housing disc 202 lies on, and is supported by, the plunger disc 106. The outermost part of the housing disc 202 generally extends slightly beyond the plunger disc 106, but very little, if any, of the foil 2 occupies that annulus so little force would be applied to that unsupported disc region. The housing disc 202 may therefore only be required to be strong enough to support the weight of the full foil 2 within the cartridge housing 200, so preventing the foil from falling out when the cartridge 300 is not in use and held vertically or otherwise moved. All parts of the cartridge housing 200 may be made from compostable and / or recyclable materials in some implementations. In other implementations, the nozzle 203, and / or the spike 210, may be the only non-compostable part(s) or the only non-recyclable part(s). The nozzle 203 may be made of a single material, or may comprise parts of different materials. The nozzle 203 may be made of or comprise the same material as the housing tube 201 and / or disc 202, or may be made of or comprise different materials. The dimensions of the tube 201 and nozzle 203 may be selected as appropriate to fit a given sealant foil 2. A foil volume of 3 10 ml is common, although other volumes of sealant - e.g. 400 ml -are provided by other known foils 2. For example, a foil 2 may have an outer diameter of 35-55 mm or 40-60 mm, and optionally of 45-50 mm. The foil 2 may have a length of between 100 mm and 300 mm. The housing tube 201 may be selected to have a similar diameter to the foil 2, such that the foil 2 can fit and slide within the tube 201 but does not have much, if any, space for sideways motion. For example, the housing tube 201 may have an outer diameter of 40-60 mm, and optionally of 45-50 mm. The housing tube 201 may have an outer diameter of just 1-10 mm greater than the outer diameter of the foil 2. The housing tube 201 may be selected to be long enough to enclose the entire foil 2, and may therefore have a length of at least 1-10 mm more than the foil length. The housing tube 201 of the examples being described is long enough to provide space for the housing disc 202 behind the foil 2, and a disc-stop 201a behind the housing disc 202. The housing tube 201 may have a length of 150-400 mm, and optionally of 200-325 mm. A given housing tube 201 may be suitable for use with a range of foils 2 of different lengths, but similar diameters or the same diameter. In the embodiment of the nozzle 203 being described, the nozzle 203 is specifically shaped to guide and hold a forward end of the sealant foil 2, to pierce the foil 2 so that the sealant can escape from the foil, and to ensure that, whilst the foil 2 is pierced, the cut part of the foil is not severed (such that it remains attached to the remainder of the foil, avoiding a risk of it otherwise clogging the nozzle outlet). The cup 204 has the following features to provide some of this functionality: Firstly, the shape of the cup 204 (the reason it is referred to as a “cup”) and its size is such that a forward end of the foil 2 is received within the cup 204 and held centrally with respect to the tube 201 as a result. The inward angle of the walls of the cup 204 towards the nozzle outlet 206 guides the foil 2 into place. The height of the cup, Hcup, is sufficient that the foil cannot easily slip out of the cup, e.g. when sealant escaping from the foil may provide a sideways or rearward pressure. Hcup may be at least 8 mm, and optionally at least 10 mm, and further optionally at least 15 or 20 mm. In the embodiment of the nozzle 203 being described with respect to Figures 2 to 16, the cup 204 has a height of around 50 mm. In other embodiments, such as that of Figures 21 to 25, the cup height may be smaller, and optionally may be only around 10 mm. The height of the cup 204 may be selected as a balance between securing the end of the foil 2 and minimising the amount of nozzle material required. The outer diameter of the cup 204 at its rearward end, Dcup outer, is selected to be approximately equal to / only slightly lesser than the inner diameter of the tube 201, Dtube mner, such that the forward end of the foil 2 is necessarily pushed into the cup 204 as the plunger 104 moves it forward within the tube 201. The cup 204 has curved sides in the embodiment 203 currently being described, and also in the embodiment 203a described below with respect to Figure 16, but can have sides at a constant angle in other embodiments such as that shown in Figures 21 and 22, so providing a more conical shape rather than a traditional bowl shape. The more conical shaped cup 204 shown in the later figures has a lesser longitudinal extent along the housing tube 201 than the cup 204 of the earlier figures, so using less material. It will be appreciated that either shape may serve the desired purpose of containing and guiding the foil 2. Further, curved sides or sides which have a corner so as to run parallel to the tube wall after an initial conical portion may facilitate a greater cup height Hcup without inhibiting plunger movement. The plunger 106 and / or disc 202 may have a narrower forward lip arranged to fit snugly within the cup 204 in some such embodiments. The wall of the cup 204 extends away from the flat inner / rearward surface of the cap 208 - a flat portion of the cap 208, with the outlet 206 extending centrally therethrough, is enclosed by the encircling cup wall 204. Secondly, the cup 204 may comprise one or more spikes 210 arranged to pierce the foil 2, or may surround one or more spikes 210 arranged to pierce the foil, and may also comprise or surround one or more features 210c, 211c arranged to prevent severing of part of the foil 2. In the embodiments shown in Figures 9 to 16, the nozzle 203 comprises a wall 210, 211 extending within the cup 204, the wall 210, 211 extending rearwardly from a rear surface of the cap 208 within the cup 204. The wall 210, 211 extends around a circumference of the channel leading through the cap 208 to the nozzle outlet 206. In the embodiments shown, the wall 210, 211 encloses a region of larger cross-section than the nozzle outlet channel, in particular having a width of at least 150% of the width of the nozzle outlet channel 206a. The wall 210, 211 may therefore act as a funnel, taking sealant from a wider area into the narrower channel 206a. In the embodiments shown in Figures 9 to 16, the nozzle 203 comprises a single spike, and the spike 210, 211 is, or is made from, the wall 210, 211. The wall 210, 211 is cylindrical / tubular such that the spike comprises a tube encircling the nozzle outlet 206a. The tube of the spike 210, 211 therefore may have a greater cross-sectional width than the nozzle outlet channel 206a, and more specifically may have a diameter of at least 150% of the diameter of the nozzle outlet channel. In the embodiments shown in Figures 9 to 16, the cup 203 therefore surrounds a single spike 210, 211. The spike 210 extends from the flat portion of the cap 208 encircled by the cup 204 in the embodiment shown - in other embodiments, the spike 210 may instead extend from a wall of the cup 204. In the embodiment shown, the spike 210 is formed integrally with the rest of the nozzle 203, including the cup 204, and of the same material. In other embodiments, nozzle components may be made separately and combined. The spike 210 of the embodiment shown comprises a hollow, tube-shaped extension of the nozzle 203 extending rearwardly within the cup 204. The rearward surface of the spike 210 is angled such that the extent of the spike 210 along the length of the housing tube 201 in use varies around the spike’s circumference, from a minimum within the cup 204 to a maximum level with the cup’s rearward edge. The hollow interior 210a of the spike 210 surrounds the inner diameter of the nozzle outlet 206, providing a path for sealant from the puncture in the foil 2, made by the spike 210, to the nozzle outlet 206. In other embodiments, the spike 210 may not be tube-shaped, and may for example be a simple prong or tooth. The spike may be made of a different material from the rest of the nozzle - e.g. the spike may be a metal wire or prong. In some embodiments, as in the example shown in Figure 9, the angled rearward edge of the tube-shaped spike 210 may itself be sufficient to pierce the foil 2. As the angled rearward edge has a rearmost tip at one location around the circumference only, the foil 2 is pierced in one location only and a section of foil is therefore unlikely to be severed - rather, a single hole will grow under the pressure of the plunger 104. In some embodiments, the rearmost region of the spike may be narrower / sharpened, and the rear part of the spike 210 which has a shorter extent may be smoothed - e.g. by sanding or by shaping of a mould, to reduce the chance of further puncturing or slicing of the foil 2. The tube of the spike 210, 211 may therefore comprise an angled rearward end, with a point of the angled rearward end of the tube of the spike providing a piercing edge arranged to pierce the foil in use. In some embodiments, the wall edge towards / in the region of its piercing point may be sharpened, and the wall edge may be smoother / rounded / less sharp away from its piercing point or edge. In other embodiments, such as that shown in Figures 11 and 12, a more complex shape of an otherwise-similar spike 210 may be used to facilitate puncturing of the foil 2, and to protect against the foil severing. In particular, in this example 203, the spike 210 has a rearward tooth 210b arranged to pierce the foil 2. This tooth, or pointed protrusion, 210b extends rearwardly to form a rearmost part of the spike 210 . The spike 210, as for that of the embodiment of Figure 9, is tube-shaped with an angled rearward surface, as if a tube had been cut at an angle, but in the present embodiment the rearmost portion of the tube’s circumference is cut flat, with the tooth 210b protruding rearwardly from that flat portion. The tooth 210b is narrow and pointed to better puncture the foil 2. In this embodiment, the circumference of the spike 210 also has a notch 210c located diametrically opposite the tooth 210b. The wall of the spike 210 provides two shoulders 210d for the notch 210c - this notch may help to ensure that even if the rim of the spike 210 tears the puncture-hole made by the tooth 210b wide, a strip of the foil 2 remains intact such that no part of the foil is completely separated from the rest of the foil. The notch 210c defines a minimum rearward extent of the spike 210 around its circumference. The '‘gate" or shoulders 2 lOd rearward of, and on either side of, the notch and 210c, may serve to push the cut portion of foil into the rest of the “sausage”. This may help to ensure that the nozzle outlet 206 is not blocked by the loose foil when the material (sealant) is pumped out. The tube of the spike 210 therefore comprises a notch 210c extending forwardly. The edges of the notch 210c, and / or of the shoulders 210d to either side thereof, may be smooth / rounded to avoid piercing or tearing the foil. Such a notch 210c may also be used in embodiments without teeth 210b, and may be located diametrically opposite a piercing edge or point of the spike 210 in such embodiments. In other embodiments, multiple spikes 210, or multiple teeth 210b protruding from a single spike 210, may be present. The example 203a shown in Figure 16 is generally like that described above with respect to Figure 13, but with key differences relating to the spike 211. The spike 211 of Figure 16 has a generally similar shape to that 210 of Figure 13, but three teeth 211b extend rearwardly from the flat rearward part of the spike’s circumference instead of a single tooth 210b, and the teeth 211b are also much longer - extending beyond / out of the cup 204. In addition, the notch 210c and shoulders 2 lOd for ensuring that no portion of the foil is severed, and that the cut portion of foil is pushed backward away from the outlet 206, are replaced with a cross-bar 211c. The cross-bar 211c extends across the diameter of the spike 211 and has a smooth rearward surface so as not to pierce the foil 2. The cross-bar 211c serves to block further forward movement of a cut piece of foil 2, whilst allowing sealant past. The cross-bar 211c may also be referred to as an elongate barrier, or strut. A notch 210c and a cross-bar 211c may both be provided in some embodiments. In the embodiments of Figures 9 to 11, the spike 210 is fully contained within the cup 204 / does not extend further rearwardly than the cup does. In other implementations, such as that shown in Figure 16, the spike(s) 211 extend further rearwardly than the cup - this may facilitate piercing of the foil 2. It will be appreciated that the spike(s) 210, 211 may be what limits the maximum forward-most position of the plunger 104, 106, however - shorter spikes may therefore be preferred to minimise wastage of the sealant, although retractable spikes may be used in some embodiments. The nozzle 203a as shown in Figure 16 may be used with the other components 201, 202, 100, etc. as shown in Figures 1 and 2. Figures 17 and 18 show the tube 201 in more detail - the rear end view shown in Figure 17 shows that the tube 201 has a wall thickness between an outer tube diameter (Dtube^outer) and an inner tube diameter (DtUbejnner). In the embodiment being described with respect to these figures, D;ubc^uter is 55 mm and DtUbejnner is 52 mm, giving a wall thickness of 3 mm. This wall thickness may be selected to allow sufficient strength to be provided even when the tube 201 is made of cardboard. The tube length, LtUbe, 300 mm, and more specifically is 285 mm, in the example pictured. It will be appreciated that tube dimensions may be selected as appropriate for a given foil 2 and a given tube material. Figures 19 and 20 show close-up views of the housing disc 202 which sits behind the foil 2 within the tube 201 in use. In the example being described, the disc has a diameter, Ddisc, of 52.5 mm - this is fractionally wider than the inner diameter of the tube 201, so relying on some flexibility of the tube or disc and ensuring a tight fit. The tight fit may serve to prevent any sealant from escaping in use, and / or to frictionally retain the disc 202 within the tube 201, even against gravity and the weight of the foil 2 if the tube 201 is held vertically upward when filled in use. In other embodiments - e.g. in embodiments with a stiffer tube and disc material - the disc diameter may be selected to be equal to, or fractionally less than, the inner diameter of the tub 201. In such embodiments, the tube 201 may be fitted with a rearward rim or lip 201a as shown in Figure 15 to retain the disc 202. In the embodiment show, the disc 202 has a height (which may be referred to as length, as it is parallel to tube length in use) of around 5 mm. In the embodiment shown, the disc 202 has a chamfered forwards edge, with its sides angled inwards by 45° over the forward-most 1 mm of its length. The disc 202 is therefore narrowest at its forward edge, facilitating insertion into the tube 201 from behind. This may also allow the disc 202 to fit into the cup 204 if pushed far enough forward (depending on spike length). Figures 21 to 24 show a third embodiment of a nozzle 203b as described herein. The nozzle 203b is generally similar to those 203, 203a described above, and the below description focuses on the differences for clarity. The threaded nozzle outlet 206 and the cap portion 208 of the nozzle 203b are generally as described above, with the main differences being for the cup 204 and spike(s) 212. In particular, for the cup 204, the cup 204 of this embodiment has straight, angled, sides instead of curved sides, so providing a conical shape extending from the cap 208 rather than a curved bowl shape. In addition, the cup 204 is relatively short, having a height, Hcup, of only around 10 mm in the example pictured. The cup 204 is symmetrical, with an outer diameter at its rearward end, of around 50 mm, and more specifically of 51 mm in this embodiment, fitting within the 52 mm inner diameter of the tube 201 without excessive space therebetween. A slightly tighter, sliding, fit between the rearward rim of the cup 204 and the tube 201 may be provided in other embodiments. The cone angle of the cup 204, Acup, is around 74°, and more specifically is 73.7°, in the example being described. In other examples, the cone angle may be in the range from 50° to 80°, and optionally in the range from 70° to 78°. The wall thickness of the cup, Tcup, is around 1.4 mm in the example being described, and may be in the range of 0.5 mm to 3 mm, for example, depending on factors including material and the required strength. The nozzle 203b shown has a total height, Hnozzie, of around 32 mm. Of this, the height of the cup, Hcup, takes 10 mm and the height of the nozzle outlet, Houtiet, takes around 15 mm. This leaves around 7 mm for the thickness of the cap 208, between the outlet nozzle 206 and the cup 204. Proportions may vary in other embodiments. The spikes 211 are fully contained within the cup 204 / do not extend further rearward than the cup 204 in this embodiment (Hspike<HcuP, and more specifically Hspike is 9.8 mm and HCuP is 10mm in the example shown). More generally, spikes 210, 211 may extend at least 5 mm, and optionally at least 8 mm, rearwardly of the cap’s rearward surface / the base of the cup 204. Spikes 210, 211 may extend at least 50%, and optionally at least 80% or 90%, of the rearward extent of the cup 204. Turning now to the spike(s), in this embodiment 203b the generally tubular, single, spikes 210, 211 of the preceding embodiments are replaced with a ring of spikes 212 within the cup 204. A total of ten spikes 212 are provided in this example, although it will be appreciated that the number of spikes may vary, for example between four and twelve, and optionally there may be 6, 7, 8, 9 or 10 spikes. The gaps between the spikes 211 may act as the notch 110c described above, providing areas in which the foil 2 is not pierced or torn. The spikes 212 are arranged near to and within an inner circumference of the cup, Dcupinner. As can be seen most clearly in Figure 24, the inner diameter of the outlet, is constant (Dnozzie mner) in the nozzle outlet portion 206 of the nozzle 203b, and then widens within the cap 208 to a wider diameter, Dnng, around which the spikes 212 are arranged. In the embodiment being described, DnOzzie_inner is around 10 mm and Dring is around 20 mm (and more specifically is 21 mm in the example shown). The widening of this space within the cap 208 is generally bowl-shaped, with a more rapid increase in width at first / on leaving the nozzle outlet 206, then slowing to a more gradual widening rearwardly. A more conical shape may be used in other embodiments. The spikes 212 are evenly spaced around this ring in the embodiment shown, with each spike 212 taking 12° of the ring (Aspike width), and an angular spacing (Aspacing) of 36° from the centre line of one spike to the centre line of the next. It will be appreciated that spike spacings and / or sizes may differ in other embodiments, and that the spikes may be arranged unevenly around the circumference. The spike size and spacing between spikes may be selected to reduce or avoid a risk of any portion of the foil becoming detached - for example, a number of spikes may be kept below 15 or 20, or an angular spacing of spikes may be kept above 25°, or an uneven spacing with a larger gap between spikes in one region may be provided, to reduce the risk of punctured holes joining. The spikes 212 have angled sides so as to be subtended by a constant angle, and also have angled rearward surfaces so as to provide a sharp point for puncturing a foil 2. The spikes have spike angles, Aspike, of around 23° in the example shown, so providing a sharp point. Angles may vary in other embodiments. The outer edges of the spikes 212 define a ring with a diameter, Dspikes^outer, of around 30 mm, and more specifically of 29 mm in the example shown. The spikes 212 therefore each have a radial extent of around 4 mm at their bases, and narrow to their tips. In the embodiment shown, an inner diameter of the cup 204 where it meets the cap 208, 0-,, „,nd. is around 2 mm larger than so providing some clearance between the spikes 212 and the cup wall. In other embodiments, the spikes 212 may merge with / extend from the cup wall and there may not be a flat region between the cup and the spikes. The nozzle 203b as shown in Figure 21 may be used with the other components 201, 202, 100, etc. as shown in Figures 1 and 2 - the nozzles 203, 203a, 203b described herein may all be interchangeable. As for the cap 208 described with respect to Figure 13, the cap 208 again has a slightly narrower rearward portion 208b with a diameter arranged to fit slidingly within the housing tube 201, so providing a rim or lip arranged to seat the cap 208 securely at the front of the tube 201. The cap 208 has a total height, Hcap, of around 7 mm in the embodiment pictured, with the narrower rearward portion that provides the lip having a height, Hcap2, of around 4 mm. The cap 208 shown here has no ribs, however, instead relying on a tight fit between the circumference of the cap 208 and the tube 201 (and / or an adhesive) to hold the cap 208 in place. In the example shown, the outer cap diameter, Dcap, is 55 mm, so equal to the tube outer diameter such that the cap 208 cannot fit fully within the tube 201 (at least not without deformation). The cap diameter for the rearward portion, Dcap rear, is smaller so as to fit within the tube 201, and more specifically is equal to or around 52.2 mm in the example shown. As for the disc 202 described with respect to Figures 19 and 20, the cap 208 of the nozzle 203b shown has a chamfered edge 208c to facilitate insertion into the tube 201 (this time, a rearward edge as the cap 208 is arranged to fit onto the front of the tube 201). The chamfered edge 208c again extends over around 1 mm of the cap height. Heap, at an inward angle of around 45°, in the example shown. The nozzles 203, 203a, 203b may all have a nozzle outlet outer diameter, Dnozzie^outer, of 15 mm to fit with standard attachments for sealant guns (e.g. caps and shaped applicators). Nozzle outlet dimensions may vary in other embodiments, and a provided kit of parts may include one or more caps or and shaped applicators arranged to be connected to a threaded nozzle outlet 206, or the nozzle outlet 206 may be arranged to be used as-is, without any attachment, and may not be threaded. A cap for an unthreaded nozzle outlet 206 may also be provided. In the embodiments described above, the slider takes the form of a disc 202. However, it will be appreciated that other forms are possible, for example as shown in Figure 26 which illustrates a disc-shaped slider 202 and a cylindrical slider 202a. The second slider design 202a may be described as a hollow cylinder or tube, closed at one end, or as being cup-shaped. The side walls of the cylindrical slider 202a contact the inner surface of the housing tube 201. The cylindrical slider 202a provides increased friction along the inner wall of the housing tube 201, and may facilitate holding the foil in place within the housing tube 201 without a need for slider-stops as described for the disc-shaped slider 202 described above. The cylinder 202a is hollow and closed at a front end only, so providing the increased area for friction whilst allowing the slider 202a to remain thin-walled, using minimal material. The plunger disc 106 of a sealant gun is arranged to fit within the slider 202a, such that the plunger disc 106 contacts the rear face of the circular front of the slider 202a - force is therefore transferred to the foil via the front face / closed forward end of the slider 202a, without exerting pressure on the slider walls. The slider walls can therefore be thin as they do not require the mechanical strength to stand up to the applied force. Figure 26 is provided to show the shape of the slider 202, 202a, and in particular the increased frictional contact for the hollow cylindrical slider design 202a, and may not be to scale - in particular, the slider 202, 202a may generally be thinner with respect to tube diameter than is shown in the drawings. It will be appreciated that the specific embodiments described herein are provided by way of example only. For example, the cup 204 is relatively thin-walled in the embodiments shown to reduce the volume of material used. In alternative embodiments, the cup 204 may instead take the form of a hollow or depression in a solid plug or block of material of the nozzle 203 (e.g. the cap). The cup may be provided by a widening portion of the nozzle outlet channel 206a within the cap 208 in such embodiments. By way of further example, the foil-breaching means 210, 212 may be mounted on, or be a part of, the housing tube 201 instead of being provided by the nozzle 203 in some embodiments - for example taking the form of an angled protruding wire or spike pointing radially inwardly and rearwardly along the housing tube 201. In the embodiments described herein, the nozzle 203 is generally made of plastic whereas the housing tube 201 is generally made of easily-recycled cardboard, so having the foil-breaching means 210, 212 as a part of the nozzle is generally preferred for ease of manufacture and recycling. However, in some embodiments a removable, stiff metal wire or similar may be mounted on, but easily removable from, the housing tube 201, so serving as a foil-breaching means 210 and being separable for recycling / disposal. By way of further example, in some embodiments, the nozzle 203 may not comprise a cup 204. The cap 208 may instead have a flat rearmost surface, optionally with one or more foil-breaching means 210 extending therefrom. The use of a cup 204 may generally be favoured as a guide for the end of the foil 2, and as a funnel for the ejected sealant (and the cup 203 may reduce sealant wastage and / or improve ease of detaching and recycling the housing tube in some embodiments), but reducing material required for the nozzle 203 may be a higher-priority consideration in some embodiments, and the cup 204 may therefore be left out of some designs. By way of further example, whilst foils 2 are generally cylindrical in shape, so best received in a cylindrical housing tube 201, shapes may vary in some embodiments. For example, a foil 2 with a square or rectangular cross-section may be used in some embodiments, and the housing tube 201 may be shaped accordingly. It will be appreciated that the nozzle 203 / cap 208 and slider 202 design and shape may be adapted accordingly, without departing from the scope of the invention - it is not necessary for the housing tube 201 to be cylindrical (e.g. it may be rectangular in cross-section, or otherwise adapted to the shape of a foil with which it is designed to be used). Many modifications and variations are therefore possible without departing from the 5 scope of the invention as defined in the appended claims.

Claims

1. A sealant cartridge housing comprising:a housing tube arranged to receive a sealant foil therewithin; anda nozzle on the front end of the housing tube, the nozzle comprising a nozzle outlet extending forward of the housing tube,and wherein the sealant cartridge housing further comprises a foil-breaching means within the housing tube.

2. The sealant cartridge housing of Claim 1, further comprising a slider, the slider being slidably received within the housing tube, and slidable along the length of the housing tube when a force is applied to the slider.

3. The sealant cartridge housing of Claim 1 or Claim 2, wherein the foil-breaching means is provided by the nozzle.

4. The sealant cartridge housing of any preceding claim, wherein the nozzle comprises a cup extending rearwardly within the housing tube, the nozzle outlet comprising a channel passing through a base of the cup, and wherein the foil-breaching means is or comprises a spike extending rearwardly within the cup.

5. The sealant cartridge housing of any preceding claim, comprising a plurality of spikes extending rearwardly.

6. The sealant cartridge housing of Claim 5, wherein the spikes are arranged in a ring around the channel, and within the cup, and wherein optionally there are at least six spikes, evenly spaced around the ring.

7. The sealant cartridge housing of any preceding claim, wherein the housing tube has at least one of:(i) an outer diameter of 40-60 mm, and optionally of 45-50 mm; and(ii) a length of 150-400 mm, and optionally of 200-325 mm.

8. The sealant cartridge housing of Claim 4 or any claim dependent thereon, wherein the or each spike is oriented parallel to the length of the tube and comprises a rearward cutting edge or point.

9. The sealant cartridge housing of any preceding claim, wherein the nozzle comprises a cap arranged to be seated on the front end of the housing tube, and wherein optionally the channel widens within the cap, from a first diameter at a rearward end of the nozzle outlet to a second, larger, diameter at a rearward edge of the cap.

10. The sealant cartridge housing of any preceding claim, wherein the nozzle comprises a wall extending around a circumference of the nozzle outlet channel, and wherein optionally the wall encloses a region of larger cross-section than the nozzle outlet channel, optionally with a width of at least 150% the width of the nozzle outlet channel.

11. The sealant cartridge housing of Claim 10, wherein the sealant cartridge housing comprises a single spike, and the wall is a part of the spike, the spike providing the foil-breaching means.

12. The sealant cartridge housing of Claim 11, wherein the wall is cylindrical such that the spike comprises a tube encircling the nozzle outlet.

13. The sealant cartridge housing of Claim 12, wherein the tube of the spike comprises an angled rearward end, the point of the angled rearward end of the tube of the spike providing a piercing edge.

14. The sealant cartridge housing of Claim 13, wherein the tube of the spike has a sharpened wall edge towards its point, and a relatively smoother wall edge away from its point.

15. The sealant cartridge housing of Claim 12, wherein the spike comprises a pointed protrusion extending rearwardly from a rearmost part of the tube.

16. The sealant cartridge housing of any of Claims 12 to 15, wherein the tube of the spike comprises a notch extending forwardly, the notch optionally being smooth.

17. The sealant cartridge housing of Claim 16, wherein the notch is diametrically opposite a piercing edge of the spike.

18. The sealant cartridge housing of any preceding claim, wherein the housing tube, and optionally also the slider where present, is made of cardboard.

19. A nozzle for a sealant cartridge housing, the nozzle comprising:a nozzle outlet comprising a channel;a cup extending rearwardly behind the nozzle outlet, and wherein the nozzle outlet channel is arranged to pass through a base of the cup; anda spike or cutting edge facing rearwardly.

20. A sealant cartridge comprising a sealant cartridge housing as described any of Claims 1 to 18, with a sealant-filled foil mounted within the housing tube.

21. A sealant applicator comprising:a sealant gun comprising a body and a plunger arranged to move along the body;a housing tube arranged to fit slidingly within the gun body,a slider located towards the rear of the housing tube, the slider being arranged to contact the plunger;a sealant-filled foil mounted within the tube; anda nozzle mounted on the front of the tube, the nozzle comprising a nozzle outlet extending forward of the housing tube and a cup extending rearwardly within the housing tube and arranged to receive a front end of the foil,and wherein the sealant applicator further comprises a foil-breaching means located within the housing tube and arranged to breach the foil,and wherein the sealant gun is arranged such that the foil is compressed as the plunger moves forward, ejecting the sealant from the foil, through the breach in the foil to the nozzle.

22. The sealant applicator of Claim 21, wherein the tube is made of cardboard, and optionally wherein the slider is also made of cardboard.

23. The sealant applicator of Claim 21 or Claim 22, wherein the nozzle is made of 5 plastic.

24. The sealant applicator of any of Claims 21 to 23, wherein the tube and nozzle together form the sealant cartridge housing of any of Claims 1 to 18.10 25. A kit of parts for a sealant applicator, comprising:the sealant cartridge housing of any of Claims 1 to 18;a sealant-filled foil mounted within the sealant cartridge housing; and a sealant gun arranged to receive the sealant cartridge housing.

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