ASTM D925

Rubber in contact with light colored organic finishes may stain the surfaces in contact with the rubber (contact staining) and surfaces adjacent to or beyond the rubber (migration staining), especially under conditions of heat, pressure, or sunlight. When a light colored rubber veneer or organic coating covers a staining rubber compound, the staining ingredients can diffuse through the veneer or coating and stain the surface (diffusion staining). This staining of light colored surfaces is objectionable to the consumer.

These test methods provide a means of evaluating staining characteristics of rubber compounds but may not necessarily duplicate the effects of natural exposure conditions.

Results obtained should not be treated as being equivalent to any natural exposure, unless the degree of quantitative correlation has been empirically established for the material in question.

These test methods may be used for producer-consumer acceptance, referee purposes, and research and development work.

The two types of exposures (Fluorescent UV and Xenon Arc) are not equivalent and may produce different test results.

1. Scope

1.1 These test methods cover techniques to evaluate three types of staining that rubber may cause when in contact with, or in proximity to, another surface that may be light colored.

1.2 The test methods also describe how to qualitatively evaluate the degree of staining produced under the conditions of exposure to heat alone or heat and light.

1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents

D1148 Test Method for Rubber Deterioration-Discoloration from Ultraviolet (UV) and Heat Exposure of Light-Colored Surfaces
D3182 Practice for Rubber-Materials, Equipment, and Procedures for Mixing Standard Compounds and Preparing Standard Vulcanized Sheets
D3183 Practice for Rubber-Preparation of Product Pieces for Test Purposes from Products
E145 Specification for Gravity-Convection and Forced-Ventilation Ovens
G151 Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
G154 Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials
G155 Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials

Index Terms

color; contact stain; diffusion stain; heat discoloration; migration stain; rubber articles; rubber products; rubber stain; ultraviolet discoloration; Organic coatings; Rubber property analysis; Staining process/analysis; Sunlamp; Ultraviolet (UV) analysis--rubber; Coatings (rubber products); Contact stain; Diffusion stain; Discoloration; Migration stain; ICS Number Code 83.060

Citing ASTM Standards

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