Mapei Primer T

Mapei Primer T All-Purpose Primer for Self-Leveling Underlayments — 1 Quart / 2 Gallon

Mapei Primer T is a low-VOC, magenta-colored, water-based acrylic primer that enhances the performance and adhesion of self-leveling underlayments on nonporous and porous substrates. It's the required prep step before pouring any Mapei SLU — skipping it on nonporous surfaces is one of the most common causes of SLU bond failure. 

One-component and single-coat, it works on a wide variety of substrate conditions for faster turnaround and lower installation costs. The magenta color makes coverage control easy — you can see exactly where you've applied it and where you haven't, eliminating missed spots before the pour. Dries to a clear finish in as little as 2 hours. Low odor, no mixing required for most applications. 

Apply undiluted over nonabsorbent surfaces — ceramic tile, porcelain, VCT, epoxy moisture barriers, and wood. Dilute with water for porous concrete substrates. Interior use only; do not apply over wet substrates or asbestos-containing materials.

The 1-quart is suited for small patch areas and spot priming. The 2-gallon is the right size for full-floor SLU pours and larger commercial prep work.

• Click here for Technical Data Sheet

Do I always need to use Primer T before an SLU? Yes, on nonporous surfaces — ceramic tile, porcelain, VCT, and similar — Primer T is required to achieve proper SLU bond. On porous concrete it's still recommended to control absorption and prevent pinholes.

Do I dilute it with water? It depends on the substrate. Apply undiluted over nonporous surfaces, wood, and plywood. Dilute 1:1 to 2:1 (water to primer) over porous concrete. Use a 2:1 dilution over gypsum substrates, applying two coats if needed.

How long does it take to dry? As little as 2 hours under normal temperature and humidity conditions. Do not pour SLU until Primer T is fully dry.

Which size should I buy? The 1-quart covers small patch areas and is practical for spot priming before minor leveling work. The 2-gallon is the better value for full-floor SLU applications and larger commercial installs.

Can I use it on OSB or plywood? Yes — apply undiluted. For plywood and OSB installs, Mapei may also require Mapelath or diamond mesh on top of the primed surface depending on the finished flooring, load, and deflection criteria.

Can it be used outdoors? No — interior use only, dry environments only. Do not apply over wet substrates.

Can I use it over existing adhesive residue? Yes — apply undiluted over dense, nonabsorbent surfaces including well-adhered cutback adhesive, floor-covering adhesive, and polyurethane adhesive residues.

Is it compatible with all Mapei SLUs? Yes — use before Ultraplan 1 Plus, Novoplan 2 Plus, Ultraplan Easy, and other Mapei cementitious and gypsum-based SLUs. It is also required between multiple layers of Ultraplan 1 Plus.

Sku: 7493843