Stone Cleaning Hydrogel Composition for Controlled Release

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Solution Overview

Problem

Existing chemical cleaning methods for stone surfaces, particularly in civil and cultural heritage contexts, rely on toxic and non-biodegradable solvents or require expert preparation and application, lacking eco-sustainability, controlled release, and stability, and are not easily applicable to complex geometries.

Innovation Solution

A hydrogel formulation comprising citric acid, xanthan gum, and other agents provides a non-toxic, eco-friendly, and stable cleaning solution with controlled release, suitable for various stone types and geometries, applied as a compress and easily removable without extensive rinsing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If organic solvents are used for cleaning stone surfaces, then good cleaning results are achieved, but toxicity and environmental sustainability deteriorate

Engineering Contradiction:
Improvecleaning effectivenessVSAvoidtoxicity
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the cleaning formulation by replacing organic solvents with a water-based system containing chelating agents (EDTA, citric acid) and surfactants. This parameter change maintains cleaning effectiveness through chemical complexation and surface activity while eliminating the toxicity associated with organic solvents like acetone and white spirit.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a disposable compress system made from biodegradable materials (cellulose, agar-agar, sepiolite) that delivers the cleaning formulation directly to the stone surface. This disposable approach eliminates the need for complex application equipment and ensures complete removal of the cleaning agent, preventing residual harm to the stone surface.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Object-affected harmful factors

If aqueous formulations are used for cleaning stone surfaces, then toxicity is reduced, but cleaning effectiveness deteriorates

Engineering Contradiction:
ImprovetoxicityVSAvoidcleaning effectiveness
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent creates a composite cleaning formulation combining multiple water-soluble components: chelating agents (EDTA, citric acid) for complexing metal ions, surfactants for reducing surface tension and emulsifying organic deposits, and buffering agents for pH control. This composite approach achieves cleaning effectiveness comparable to organic solvents while maintaining the non-toxic nature of water-based systems.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent introduces chelating agents as intermediary substances that mediate between the water-based formulation and the deposits on stone surfaces. These chelating agents form soluble complexes with metal ions in the deposits, enabling their removal by water without requiring toxic organic solvents.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If compress application is used for cleaning stone surfaces, then application to complex geometries is improved, but preparation complexity and expert requirement increase

Engineering Contradiction:
Improveapplicability to complex geometriesVSAvoidpreparation complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent incorporates the cleaning formulation into the compress structure during manufacturing, so that the active cleaning agents are pre-loaded and ready for immediate application. This preliminary action eliminates the need for expert preparation of the compress at the application site, while maintaining the adaptability to complex geometries that compress application provides.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The compress is designed to self-regulate the delivery of the cleaning formulation through its porous structure and capillary action, eliminating the need for expert control of application parameters. The compress automatically adapts to the stone surface geometry and controls the release of cleaning agents, reducing the skill level required for effective application.

Inventive Principle:
Principle #25Self-service

4Reliability

If abundant rinsing is used after cleaning, then removal of residues is improved, but water consumption increases

Engineering Contradiction:
Improveresidue removalVSAvoidwater consumption
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent employs biodegradable supporting materials (cellulose, agar-agar, sepiolite) that are completely removable from the stone surface without requiring abundant rinsing. These materials can be mechanically removed or rinsed with minimal water, eliminating the need for extensive water consumption while ensuring complete removal of cleaning residues.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent extracts the cleaning formulation from the compress after application, allowing the compress to be removed and disposed of while retaining the dissolved deposits. This extraction approach removes the need for abundant rinsing, as the cleaning agents and deposits are removed together with the compress, significantly reducing water consumption.

Inventive Principle:
Principle #2Taking out (Extraction)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The formulation ensures effective cleaning with minimal surface aggression, long-term stability, and easy application, reducing environmental impact and water waste, while maintaining cleaning efficacy for over a week.

Implementation Method 1

A hydrogel formulation comprising citric acid, xanthan gum, and other agents provides a non-toxic, eco-friendly, and stable cleaning solution with controlled release

Methodology Applied
Scientific EffectHydrogel: Hydrogel

Implementation Method 2

a first chelating agent consisting of citric acid

Methodology Applied
Scientific EffectChelation:

Implementation Method 3

at least one surfactant

Methodology Applied
Scientific EffectSurfactant: Surfactant

Data Source

PatentEP4674936A1Stone surface cleaning hydrogel formulation
Publication Date: 2026.01.07 COSTANTER SPA
  • EP4674936A1 patent drawingFigure 1
  • EP4674936A1 patent drawingFigure 2
  • EP4674936A1 patent drawingFigure 3~4

AI summary

The present patent application concerns a hydrogel formulation for cleaning stone surfaces comprising: a first chelating agent consisting of citric acid, a second chelating agent selected from the group consisting of Tetrasodium glutamate diacetate, Trisodium dicarboxymethyl alaninate and combinations of the above, a supporting agent consisting of xanthan gum, at least one co-densifier, at least one surfactant, at least one antibacterial and/or anti-mould, water, wherein the weight ratio of the sum of the first chelating agent and the second chelating agent to the xanthan gum is comprised from 1:0.7 to 1:1.6.