The chemical resistance of a material or surface can be determined in compliance with ISO 2812 Paints and varnishes – Determination of resistance to liquids – Part 1: Immersion in liquids other than water (ISO 2812-1:2007); German Version EN ISO 2812-1:2007 or Part 4: Spotting methods (ISO 2812-4:2007); German Version EN ISO 2812-4:2007. With these methods, a material or surface is exposed to the relevant chemical for a longer, defined period of time and the relevant area then inspected microscopically. Possible changes which could occur include:
On completion of the defined test period, any residues of test liquid are removed and the material surface assessed and analyzed for visible alterations in accordance with DIN EN ISO 4628-1 to -5. To ascertain a possible regeneration time, the assessment is made once immediately after removal of the test liquid and again one hour later. In compliance with DIN EN ISO 4628-1, the following criteria are grouped into Classes 0 to 5: amount of damage (N), size of damage (N) and intensity of alteration (I). Any other changes observed are also noted. The assessment is made as shown below:
“Blistering, N2-S2” or “Discoloration, I1”
Any increase in the concentration of the test liquid on a surface due to drying in the real cleanroom environment must also be taken into consideration. The test procedure proves whether a material or surface is “resistant”, “partially resistant” or “not resistant” to a specific chemical over a defined period of time.