Mapei Keracaulk U Unsanded Acrylic Grout Caulk 311 mL Gray

Keracaulk U Unsanded Acrylic Grout Caulk in Grey is an unsanded siliconized acrylic caulk colour-matched to Mapei grout. On paper that is ASTM C834. For joints up to 1/4". It is what goes in the change-of-plane joints a cement grout should never fill, so the wall-to-floor and inside corners. Work on about 24 to 25 linear ft from a 311 mL cartridge at a 1/8" joint, and roughly 48 to 50 linear ft at 1/16" or 11 to 13 at 1/4". Keep water off it for at least 72 hours. It dries in 24 to 48 hours and takes paint after 24. It is the sealant, so nothing goes over it. Interior only. Not under constant water immersion, not in high-wear areas, and not over asbestos-containing substrates. New concrete cures 30 days first. Use a foam backer rod where the joint is deeper than 1/4", and do not spread it thin like paint. It can stain porous stone, so test it. Colours are matched to the grout range but can vary slightly from the bag. Both the Mississauga and Barrie stores carry it.