Coremat Xi Core Bulking Mat - 2mm and 4mm, 39.37 in Wide

Coremat® Xi is a microsphere-filled polyester nonwoven that you lay between glass plies to build laminate thickness fast. Thickness is what makes a panel stiff, so a layer of Coremat between two skins of chopped strand mat adds stiffness for far less weight than building the same thickness in glass, and it blocks print-through so the reinforcement does not telegraph into your gelcoat. 39.37" (1 m) wide, in 2 mm and 4 mm.

It wets out with polyester, vinyl ester or epoxy, and the built-in resin indicator shows dry spots as you roll it out. Plan resin before you start: 2 mm takes up about 1.2 kg/m² (3.9 oz/sq ft) and 4 mm about 2.4 kg/m² (7.9 oz/sq ft). Always laminate glass on both sides; Coremat is a bulker, not a surface ply.

It is made for hand lay-up and spray-up: hull sides, decks, liners, molds, panels and tanks. It is not for vacuum bagging, infusion or prepreg, because the pressure crushes it. Keep rolls in the bag and out of direct sunlight so the resin indicator keeps working. Pair it with 1.5 oz chopped strand mat skins.