Very porous walls can soak up paint and dry patchy. Short answer: National Penetrating Sealer is a water-based, alkali-resistant vinyl acrylic copolymer sealer that National describes as having excellent penetrating properties. It is mainly for sealing plaster, concrete and similar surfaces, inside and out. One coat covers about 10.5 m² per litre and can be recoated in 2 to 3 hours.
Key facts
| Type | Water-based vinyl acrylic copolymer emulsion, alkali resistant |
| Surfaces | Porous and non-porous surfaces such as plaster and concrete, interior and exterior (the sheet also lists asbestos) |
| Finish and colour | Smooth, semi-transparent |
| Volume solids | 31 ± 2% |
| Spreading rate | 10.5 m² per litre (theoretical) |
| Film per coat | 30 microns dry (100 wet) |
| Drying at 30°C | Touch dry 1 hour; recoat after 2 to 3 hours |
| Application | Brush, roller or spray |
| Thinning | 10 to 15% with water, depending on the surface |
| Shelf life | 18 months, sealed |
How to use it
- Make sure the surface is dry and clean, as the data sheet requires.
- Apply one coat, thinned 10 to 15% with water.
- After 2 to 3 hours, continue with the system for your finish. The data sheet does not name one, so check the finish’s own data sheet or our interior wall system guide.
Penetrating Sealer vs PVA Primer Sealer
| Penetrating Sealer | PVA Primer Sealer | |
|---|---|---|
| Binder | Vinyl acrylic copolymer | PVA |
| Colour | Semi-transparent | Clear |
| Volume solids | 31 ± 2% | 30 ± 2% |
| Spreading rate | 10.5 m²/L | 10 to 15 m²/L |
| Application | Brush, roller or spray | Brush or roller |
| Described as | Alkali resistant, excellent penetration | Good sealing, good adhesion to cementitious surfaces |
How much to buy
One coat on 50 m² needs about 4.8 litres, and on 100 m² about 9.5 litres, by our calculation.
Frequently asked questions
Sealer or primer?
National’s systems name specific primers for each finish. Check the system you are using, or compare with Acrylic Primer and PVA Primer White.
Which National sealer or primer?
| Penetrating Sealer | PVA Primer Sealer | Acrylic Primer (W.B.) | |
|---|---|---|---|
| Resin | Vinyl acrylic copolymer | PVA | Acrylic |
| Look | Semi-transparent | Clear | White |
| Volume solids | 31% | 30% | 36% |
| m² per litre | 10.5 | 10 to 15 | 10 to 12 |
| Application | Brush, roller or spray | Brush or roller | Brush, roller or spray |
Step 1: prepare the surface
- National’s surface preparation guide asks for a clean, dry, sound surface. Wash exteriors with high-pressure water (2200 psi minimum) and let them dry.
- Remove laitance, efflorescence and loose material.
What the numbers mean
Coverage = 31 × 10 ÷ 30 ≈ 10.3 m² per litre, matching the sheet’s 10.5. Wet film = 30 ÷ 0.31 ≈ 97 microns, matching its 100.
| Area, one coat | Litres at 10.5 m²/L |
|---|---|
| 45 m² (bedroom walls) | about 4.3 L |
| 200 m² (two-bed flat) | about 19 L |
| 400 m² (villa exterior) | about 38 L |
Mistakes to avoid
- Using it where a topcoat’s sheet names a different primer.
- Over-thinning. Keep to 10 to 15% water.
- Topcoating before 2 to 3 hours at 30°C.
Buy in Sharjah and Dubai
Shop National Acrylic Primer 3.6 L, or message us on WhatsApp for Penetrating Sealer. See all National Paints products and guides.
Sources
- National Penetrating Sealer data sheet (PDF, via AEC Online)
- National PVA Primer Sealer data sheet (PDF, via AEC Online)
- National Paints surface preparation guide, Sec. A-2 (PDF)
Retrieved 3 November 2026. Quantities are our own calculations. The main image is illustrative.
