Texrite 31475 Polymer-Modified Multi-Purpose Thin-Set Mortar 50 lbs Bag Gray. Multi-Purpose is a professional grade, specially refined dry-set mortar with latex-polymer powder pre-blend in the bag. Composed of portland cement, sand and special polymer additives, multi-purpose is used as a bond coat for setting all types of ceramic tile, porcelain tile, marble and stone over a variety of substrates. Multi-Purpose offers the economy and ease of application of dry-set mortars while significantly improving bond strengths, freeze-thaw stability, flexibility and other qualities.