All-Purpose Primer for Self-Leveling Underlayments Primer T is a low-VOC, water-based acrylic primer that enhances the performance and adhesion of self-leveling underlayments (SLUs) on nonabsorbent surfaces such as ceramic tile, vinyl composition tile (VCT), epoxy moisture barriers and adhesive residue, as well as profiled, absorbent surfaces. Suitable for a wide variety of substrates, Primer T combines excellent versatility with an easy, low-odor application.