Sealing the change-of-plane joint? Keracaulk S Sanded Siliconized Acrylic Caulk in Alabaster is the flexible caulk that goes where grout would crack — tub-to-wall, counter-to-backsplash, floor-to-wall, expansion joints. Sanded or unsanded acrylic with siliconized polymer for paintable, color-matched finishes near the grout. Matches Mapei grout in Alabaster so the seam visually disappears.