Abrasion is the result of mechanical phenomena, such as rubbing or/and scraping, onto matter. In practice abrasion appears continuously on a large variety of objects e.g.:
" blowing air carrying sand onto architectural and car paintings
" brushing during cleaning of architectural and car paintings
" rubbing by shoe soles, sometimes loaded with sand, onto floor coatings
" rubbing by cloth or human skin onto furniture finishes
" marring with harder objects (buttons, keys) of decorative finishes of furniture or cars.
The result is experienced either as marring or wearing. Marring is caused by a deformation of the surface without removing any material. Wearing or abrasion is caused by a permanent removal of the coating material.
Abrasion is related to mechanical properties of matter such as hardness and elasticity. This is why different test methods tend to give different results, depending on the proportion hardness/elasticity involved resulting in different removing mechanisms.
The Erichsen Model 494 MC, a washability tester is a polyvalent machine designed for testing the washability, cleanability, brushability, wet scrub resistance or abrasion resistance of a large number of different materials such as paints, lacquers, inks, coatings, leather sheets, wood panels, plastics, printed materials, fabrics, etc.
The machine will linearly move an abrasive tool back and forth onto a test surface. The abrasive tool might be a brush (eventually containing an abrasive medium), a sponge or an abrasive pad. In some cases a stroke of emery cloth is fixed to the abrasive tool.
The machine will count the number of cycles (one cycle is a completed back and forth move) made in order to obtain a certain erosion effected to the test film.
The result might be expressed as the number of cycles needed to remove a film completely or as an amount (weight) of film material removed per unit of tested surface and per cycle.
Cleanability: the ability of a dry coating film to withstand penetration by soiling agents and to be freed from them without an excessive amount of film being removed by the cleaning process.
Wet scrub resistance: the ability of a dry coating film to sustain less than a given loss in film thickness, averaged over a defined area when exposed to 200 wet scrub cycles.
DIN 53 778, part 2(replaced by EN ISO DIN 11998 in Dec 2001 but still used by a lot of customer).