Method for determining the surface gloss of a colour standard

Abstract

The invention relates to a method for determining the gloss of a colour standard comprising the following steps: A) experimentally determining reflection spectra R(exp) of the colour standard, comprising a first reflection spectrum and a second reflection spectrum, with an integrating sphere colour measurement instrument, wherein said first reflection spectrum is obtained at (A1) d / 8-geometry with the specular component included, and said second reflection spectrum is obtained at (A2) d / 8-geometry with the specular component excluded, and B) converting reflection spectra data of the experimentally determined reflection spectra R(exp) of the colour standard to gloss values by: B1) acquiring the difference reflection spectrum ΔR of the experimentally determined reflection spectrum R(exp) with the specular component included (A1) and the reflection spectrum R (exp) with the specular component excluded (A2), and B2) determining the gloss values corresponding to said difference reflection spectrum ΔR with the assistance of previously prepared calibration curves, representing the functional relationship between the difference reflection spectrum ΔR and the gloss values measured at one or more gloss angles.

Description

FIELD OF THE INVENTION[0001]The invention relates to a method for determining the gloss of a colour standard. The method can be used in the paint industry or other paint related fields.DESCRIPTION OF RELATED ART[0002]In industrial colour applications a variety of instruments are utilised for the assessment of colour and gloss of surface coatings and corresponding differences between sample pairs. Wherever technically feasible, visual assessments are replaced by instrumental assessments, which hence have to be reliable on the one hand and in conformity with visual perception on the other. Modern colour management systems have to be capable of dealing with colour information of is different sources and account for specific differences of distributed heterogeneous instrumental families and historical data.[0003]A very special problem in this context is the instrumental characterisation of physical surface texture of coatings giving rise to surface gloss which may assume any value betwe...

AI Technical Summary

Benefits of technology

[0011]The present invention provides a method for determining the gloss of a colour standard, which makes use of general instrument profiles between an integrating sphere colour measurement instrument and a gloss measurement instrument equipped with three gloss-angle measurement geometries. These instrument profiles allow converting reflectance data to gloss information so that once the profiles are established the integrating sphere colour measurement instrument would provide reflectance data and gloss data, i.e., a gloss measurement instrument would be obsolete. The latter fact is particularly interesting for applications of distributed systems such as those running in refinish paint body shops to instrumentally support the car paint repair process. The necessary equipment can be reduced further and made more attractive from the pricing and efficiency perspective.

[0019]The method of the present invention may be adopted to define a single and continuous gloss scale better suited for the exchange of instrumental gloss information between different parties and to reduce the number of necessary instruments to run special applications. Discontinuities in gloss scale, which in the is transition region might give rise to non-unique measurement results, can be completely eliminated by the new method.

Problems solved by technology

A very special problem in this context is the instrumental characterisation of physical surface texture of coatings giving rise to surface gloss which may assume any value between highly glossy and perfectly matt samples.

Realistic analytical representations of the textured air / paint interface are difficult to develop and so far not applied to studies of textured surface coatings.

Below this limit the quality of predicted formulas deteriorates considerably with decreasing degree of surface gloss.

A further disadvantage is that an additional gloss measurement device is necessary to obtain gloss values.

Images