MV 603 Magnesium silicate hydrate and calcium carbonate Polar Minerals Extenders / Fillers >> Talc or Magnesium Silicate SEALANT MV Series The MV grades are designed for the paint industry and are selected for low oil absorption. Blend of magnesium silicate hydrate and calcium carbonate Mineral additive MV603 Paint, Caulk, Sealants Blend of magnesium silicate hydrate and calcium carbonate. Used as an extender in caulks and sealants. Offers low oil absorption.