A new ASTM standard provides more effective quality testing of the synthetic, hollow filaments that are often used in the manufacture of lower cost paintbrushes. The new standard, D7233, Test Method for Testing Fracture of Level Paintbrush Filaments, will allow suppliers to address issues of potential fracture. ASTM D7233 was developed by Subcommittee D01.61 on Paint Application Tools, part of ASTM International Committee D01 on Paint and Related Coatings, Materials and Applications. More.