RLA Universal Primer

For preparing floors prior to tiling or self-levelling, RLA Universal Primer provides a rapid-drying, solvent-free acrylic bond coat over both absorbent and dense surfaces. It creates a secure key for cement-based ceramic tile adhesives and levelling compounds over substrates including water-based painted surfaces, burnished concrete, ceramic tiles, and liquid waterproofing membranes.

What it does

This water-based acrylic primer seals porous subfloors to prevent rapid water loss from levelling compounds, and provides an adhesion key on dense, non-porous subfloors. It dries to a tack-free, transparent film that accepts subsequent cementitious toppings. The formulation is low-VOC, solvent-free, and cleanable with water immediately after application.

Numbers that matter

• 30 minutes to 1 hour drying time: Fast-drying acrylic formulation (tested at 23°C) that allows subsequent floor levellers or tile adhesives to be applied quickly, though cold conditions will extend this window.
• 5 to 10m² per litre coverage: Coverage yields vary depending on the absorbency of the concrete or tile substrate.
• 1:2 to 1:3 dilution ratios: Economical water dilution for porous subfloors (1 part primer to 2 parts water, or 1 to 3 for highly porous concrete) while non-porous substrates require neat, undiluted application.
• 75% relative humidity moisture limit: For concrete subfloors exceeding 75% RH when tested via the ASTM F2170 in-situ probe method, RLA Moisture Seal must be applied instead of this primer.

Where to use it

Suitable for internal subfloors including:

• Porous substrates and highly absorbent concrete.
• Non-porous substrates such as burnished concrete and liquid waterproofing membranes.
• Sound ceramic tiles and existing water-based painted surfaces.

Application steps

To determine if a substrate is porous or non-porous, puddle a 10-cent coin-sized drop of water on the surface. If absorbed in under two minutes, treat as porous. If the puddle remains, treat as non-porous.

• Porous substrates: Dilute 1 part primer with 2 parts clean water. Apply by roller or brush. Extremely porous concrete may require a second coat diluted 1 part primer to 3 parts water. Allow 30 minutes to cure.
• Non-porous substrates: Apply neat and undiluted in an even layer using a roller or brush. Extremely non-porous surfaces should be lightly sanded or ground first to improve mechanical grip. Allow to dry to a transparent, tack-free film (approximately 1 hour at 23°C) before applying levelling compounds.

Limitations

• Internal use only; do not apply to substrates subject to rising damp.
• Do not apply to ceramic tiles that have a wax surface or an excessively high gloss coating.
• Do not use solvents or acid etching to clean or prepare the subfloor.
• Minimum subfloor temperature during application must be 10°C. For temperatures below 5°C or above 35°C, contact the RLA Technical Department before starting.