Resistance to staining

 

 

Principle
Test specimens are left in contact with a series of staining agents which are likely to be encountered in everyday use. The time and conditions of contact are specified for each staining agent. At the end of the specified contact period, the specimens are washed and examined for residual surface marks. If the laminate under test meets specification requirements when tested with each of the five staining agents marked with an asterisk and underlined, then it is deemed to comply with the specification for stain resistance. The other staining agents are included for information only. In the case of a specific complaint, the staining agent in question (selected from group 1, 2 or 3) shall be used to verify the
quality of the laminate. This test method may also be used using other staining agents to cover specific requirements if agreed between supplier and purchaser.

Staining agents.
1. Group I
*Acetone
2. Group 2
*Coffee
3. Group 3
*Sodium hydroxide (25 % solution).
*Hydrogen peroxide (30 % solution).

Materials
1. Wetting agent, for example domestic detergent.
2. Solvents, such as ethanol, acetone, methyl ethyl ketone, etc. (see 26.6).
3. Soft clean cloth.

Apparatus
1. Glass covers (for example watch glasses), to restrict evaporation.
2. Vessel, suitable for heating coffee, tea and milk.
3. Thermometer, range 0 to 100 °C.
4. Hotplate, or other suitable heat source.
5. Horizontal inspection surface, illuminated by overhead and low-angle daylight or white fluorescent light of intensity 800 to 1000 lux.
6. Hard nylon bristle brush (for example a nail brush).

Test specimens
Individual specimens of any suitable size shall be used, cut from the sheet under test. Alternatively, a single piece of laminate, large enough to allow the staining agents to be applied side by side, can be used. Keep the specimen flat during the test.

Procedure
The specimens shall be initially at ambient temperature.
Apply a small quantity (for example 2 or 3 drops) of staining agent to two specimens. The staining agent shall be at the temperature. Cover the staining agent on one of the two specimens with a glass cover.
After the specified contact time has elapsed remove the glass cover. If necessary use a suitable solvent to remove the staining agent (for example butyl acetate to remove nail varnish), then wash with water containing a suitable wetting agent, and finally with ethanol or other solvents as required to clean the surface. A suitable brush may be used to remove staining agent from textured surfaces.
One hour after washing, place the specimen on the inspection surface and view it from various angles at a distance of 400 mm.

Expression of results
The effect on the surface of the specimen shall be expressed in accordance with the following rating scale for each of the five mandatory staining agents.
Rating 5: No visible change.
Rating 4: Slight change of gloss and/or colour, only visible at certain viewing angles.
Rating 3: Moderate change of gloss and/or colour.
Rating 2: Marked change of gloss and/or colour.
Rating 1: Surface distortion and/or blistering.