Pro Stick 22 is a unsanded thinset mortar used to set non-absorptive (vitreous or semi-vitreous) tiles for interior or exterior use. When mixed with water it provides a suitable bond coat to adhere tile to plaster, concrete, and masonry surfaces. For added performance, PROFLEX™ Liquid Latex Additive may be mixed with dry set mortar. With the addition of, Liquid Latex Additive, Pro Stick 22 may be applied over exterior grade plywood and PROFLEX™ membranes.