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Download Product Data
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.
Frequently asked questions
Can this primer be used on non-porous surfaces like ceramic tiles?
Yes, apply neat (undiluted) to non-porous substrates. Allow 30–60 minutes dry time to a transparent, tack-free film before applying levellers or adhesives. Degloss and clean high-gloss tiles first.
What dilution ratio is needed for standard concrete?
For standard porous concrete, dilute 1 part primer with 2 parts clean water. On very porous concrete, apply a second coat diluted 1:3 to stabilise suction and minimise dusting.
How do I test if a substrate is porous?
Perform a water drop test: place a 10-cent coin sized puddle on the surface. If the water absorbs in less than 2 minutes, treat the surface as porous. If it remains, treat it as non-porous and prime neat.
Does RLA Universal Primer manage high concrete moisture?
No, this primer is not a moisture barrier. If the in-situ relative humidity (ASTM F2170) exceeds 75%, a compatible moisture barrier must be installed before priming to avoid bond issues.
Is this primer suitable for exterior use?
No, RLA Universal Primer is for internal use only. Maintain a minimum subfloor temperature of 10 °C during application to ensure proper film formation and adhesion.
Applications and benefits
| Application | Key benefit | Primary trades |
|---|---|---|
| Priming porous concrete floors for tiling | Controls substrate suction for predictable adhesive cure and strong bond. | Tilers, Builders |
| Improving adhesion on ceramic tiles before overlays | Enhances bond to low-porosity surfaces, preventing delamination. | Tilers, Remedial |
| Preparing burnished or steel-trowelled concrete for levelling | Creates a reliable film for uniform leveller adhesion and curing. | Flooring Contractors |
| Conditioning liquid waterproofing membranes | Ensures strong, compatible bond for subsequent cement-based toppings. | Waterproofers, Tilers |
Applying RLA Universal Primer: Enhanced Protocols & Best Practices
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Assess Substrate & Porosity
Confirm soundness, dryness, and cleanliness. Perform the water drop test to determine dilution vs. neat application.
Pro Tip: Verify RH ≤ 75% via in-situ probes (ASTM F2170) before priming. -
Surface Preparation
Remove wax, oil, grease, curing compounds, and dust. Mechanically prepare if required (shot blasting/diamond grinding). Vacuum thoroughly.
Timing: Proceed when substrate temperature ≥ 10 °C. -
Mixing & Dilution
When diluting, mix primer and clean water thoroughly. Standard concrete: 1:2 (primer:water). Very porous: second coat 1:3.
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Application Method
Porous Substrates
Apply diluted primer evenly by roller or brush ensuring full coverage. Allow to dry to a transparent film.
Non-Porous Substrates
Apply primer neat (undiluted) to achieve a uniform film. Lightly sand extremely non-porous surfaces first to enhance adhesion.
Timing: Typical dry/overcoat window 30–60 minutes at 23 °C.Pro Tip: Coverage ~5–10 m²/L; adjust technique to substrate absorbency to avoid pooling. -
Overcoating
Once the film is tack-free and transparent, apply cement-based adhesives or levelling compounds according to their instructions.
Product limitations
- Not for: Exterior applications. This primer is formulated for internal use only. Maintain a minimum subfloor temperature of 10 °C during application.
- Not for: High-gloss ceramic tiles without prior deglossing or mechanical abrasion. The surface requires a mechanical key for optimal adhesion.
- Not a moisture barrier: If concrete relative humidity (ASTM F2170) exceeds 75%, a separate, compatible moisture barrier must be installed before priming.
- Not for: Substrate cleaning with solvents or acid etching. Prepare surfaces mechanically and with appropriate cleaning agents if needed.
Safety and handling
Personal protective equipment
Wear suitable gloves, protective clothing, and eye protection. Avoid direct skin and eye contact.
Ventilation
Use in well-ventilated areas. For indoor applications, ensure adequate airflow to dissipate vapours.
First aid
- Eyes: Rinse cautiously with water for several minutes. Remove contact lenses, if present, and continue rinsing.
- Skin: Wash with soap and water. Remove contaminated clothing immediately.
- Inhaled: Move to fresh air. Seek medical attention if experiencing respiratory discomfort.
- Swallowed: Do not induce vomiting. Give water to drink and contact medical services immediately.
Storage and disposal
Store in a dry area, off the ground, in unopened containers. Shelf life is 12 months. Dispose of waste in accordance with local regulations.
Substrate guide
Correct substrate preparation and primer application prevent bond failures and ensure consistent performance of subsequent layers.
Standard porous concrete
Surface prep: Ensure the surface is clean, sound, dry, and dust-free. Remove all contaminants like oil, grease, or curing compounds. Maintain a minimum subfloor temperature of 10 °C.
Primer: Required. Dilute 1 part primer with 2 parts clean water. Apply evenly by roller or brush and allow 30–60 minutes to dry to a transparent film.
Very porous concrete
Surface prep: As for standard concrete. Vacuum thoroughly after mechanical preparation like shot blasting or diamond grinding if required.
Primer: Required. Apply an initial coat diluted 1 part primer with 2 parts clean water. If suction remains excessive, apply a second coat diluted 1 part primer with 3 parts clean water to stabilise the surface.
Burnished concrete (non-porous)
Surface prep: Lightly sand or abrade the surface to enhance mechanical key. Vacuum all dust thoroughly.
Primer: Required. Apply neat (undiluted). Allow to dry to a clear, tack-free film before overcoating.
Ceramic tiles (not high-gloss)
Surface prep: Clean the surface thoroughly. If tiles are high-gloss, degloss or abrade as needed. Rinse and dry completely.
Primer: Required. Apply neat (undiluted). Allow to dry to a transparent film before applying adhesive or leveller.
Water-based painted surfaces
Surface prep: Confirm the existing coating is water-based, sound, and clean. Lightly abrade glossy surfaces. Remove any flaking paint.
Primer: Optional. For critical adhesion, apply neat (undiluted). A test area is recommended on repaints and aged coatings to verify compatibility and adhesion.
Liquid waterproofing membranes
Surface prep: Ensure the membrane is fully cured, clean, and compatible with the subsequent products to be applied.
Primer: Required. Apply neat (undiluted). Allow a clear, tack-free film to form before applying leveller or adhesive.
RLA Universal Primer Physical Properties
| Property | Value |
|---|---|
| Base Chemistry | Water-based acrylic |
| Initial Cure | 30–60 minutes at 23°C to transparent, tack-free film |
| Application Temperature | Internal use only |
| Humidity Range | Maximum 75% RH (ASTM F2170) before priming |
| Mix Ratio | Neat (undiluted) or 1:2 / 1:3 with water |
| Coverage Rate | 5–10 m²/L (dependent on absorbency) |
| Substrate Compatibility | Standard porous concrete, very porous concrete, burnished concrete, ceramic tiles (not high-gloss), water-based painted surfaces, liquid waterproofing membranes |
| Clean Up | Water |
| VOC Content | Low |
| Packaging | 5 L, 20 L |
| Shelf Life | 12 months (unopened) |
| Storage Conditions | Dry area, off the ground |
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