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® OK 520 ACEMATT® OK 900 ACEMATT® OK 607 ACEMATT® OK 607 LC ACEMATT® HK 440