EVONIK CORPORATION › ACEMATT® HK 400 ACEMATT® HK 400 $0.00 ACEMATT® HK 400 is an untreated, medium particle sized precipitated silica. It is especially recommended for pigmented systems. Add To Cart Added! ACEMATT® HK 400 is an untreated, medium particle sized precipitated silica. It is especially recommended for pigmented systems. You Might Also Like ACEMATT® HK 125 ACEMATT® HK 520 ACEMATT® 3400 ACEMATT® 790 ACEMATT® OK 500