Sales Department:         800-669-0115         sales@texrite.com
SURFACE PREPARATION
Yes. Paint overspray can act as a bond inhibiting material causing the underlayment to come loose, crack or sound hollow. As with any substrate preparation to receive underlayments or thin-set mortars, they must be clean, dry, structurally sound and free from all grease, dirt, paint, oil, curing compounds and old adhesives. The ‘best practice’ method to remove any of these would be to mechanically scarify, grind or bead blast the substrate
Primer was not used on the substrate or between lifts; incorrect latex to powder ratio when mixed; applying second lift too soon (24 hours minimum between lifts is recommended); too thick (Special 3-1 is designed for 1-1/2” maximum in one lift with a maximum of 3 lifts). Any one of these, or a combination could be causing the failure.
Too much water in the mix will result in a powdery, yellow/white, pinhole look to the surface the next day or thereafter. When excess water is used to mix FlowRite (bag directions call for 5 quarts) the chemicals float to the top, the yellow/white, powdery look. When the primer is not applied to the substrate first, the substrate absorbs the liquid and displaces air to the surface of the FlowRite, which leaves pinholes. The primer acts as a temporary sealer allowing the FlowRite to move across the floor correctly.
The existing tile must be well bonded, structurally sound, and free from sealers, grease, oil, waxes and polishes, including any grout sealers. A flat, smooth surface is desirable before installing a polished, large body stone tile, use TexRite FlowRite self-leveling underlayment or TexRite FeatherRite skim coat underlayment to prepare the tile surface. TexRite TotalContact medium bed mortar would be the best thin-set for bonding the marble to the substrate.
Thin-set is designed to bond tile or dimensional stone to a substrate in a thin layer, typically between 3/32”-3/16”. When thin-set is applied in a thick layer as surface preparation, it will shrink, crack and become loose from the substrate, especially over wood that is constantly moving due to temperature and humidity changes. Use TexRite FeatherRite, or TexRite Port-A-Patch to prepare a plywood substrate for the application of vinyl.