Short answer: National Polyurethane Topcoat is a two-pack PU finish. Mix base and hardener 4:1 by volume, use within 6 hours, and apply about 40 microns dry per coat, which gives about 13 m² per litre. National’s listed system is Guard Primer for Cement, then Interguard H.B., then two coats of PU Topcoat. Recoat after at least 10 hours; full cure takes 7 days.
Key facts
| Type | Two-pack polyurethane topcoat |
| Mix ratio | 4 base : 1 hardener, by volume |
| Pot life | 6 hours |
| Volume solids | 52% |
| Specific gravity | 1.20 |
| Spreading rate | 13 m² per litre (theoretical) |
| Film per coat | 40 microns dry (75 wet) |
| Drying | Touch dry 2 to 3 hours; recoat at least 10 hours; full cure 7 days |
| Thinner | PU Thinner, 5 to 15% |
| Airless spray | 2200 psi, tip 0.015 to 0.018 inch |
| Colours | Limited range |
| Shelf life | 18 months at 25°C |
Step 1: prepare the surface
- Concrete must be clean, dry and sound. National’s surface preparation guide calls for laitance removal and, on smooth surfaces, acid etching or roughening.
- Pressure-wash exteriors at 2200 psi minimum, then let them dry fully before priming.
Step 2: the system
| Coat | Product |
|---|---|
| 1 | Guard Primer for Cement |
| 2 | Interguard H.B. |
| 3 and 4 | Polyurethane Topcoat × 2, 40 µm dry each |
Mixing and pot life
- Stir the base, add hardener at 4:1 by volume and mix thoroughly.
- Mix only what you can apply in 6 hours.
- Thin with PU Thinner only, 5 to 15%.
What the numbers mean
Coverage = 52 × 10 ÷ 40 = 13 m² per litre, matching the sheet. Wet film = 40 ÷ 0.52 ≈ 77 microns, matching its 75. Two coats give 80 microns of PU.
How much to buy
| Area | PU, 2 coats (mixed) | Base | Hardener |
|---|---|---|---|
| 50 m² | about 7.7 L | about 6.2 L | about 1.5 L |
| 150 m² | about 23 L | about 18.5 L | about 4.6 L |
| 400 m² (villa) | about 62 L | about 49 L | about 12.3 L |
Mistakes to avoid
- Guessing the ratio. Measure 4:1 by volume.
- Using a pot after 6 hours.
- Recoating before 10 hours, or putting the surface into service before 7 days.
Frequently asked questions
Is this the same as Nationalthane?
They are separate data sheets. See our Nationalthane guide and compare each sheet before you choose.
What colours are available?
The sheet says limited colours. Message us with the shade you need and we will check.
Buy in Sharjah and Dubai
Al Tashteb Al Saree is an authorised National Paints retailer in Bu-Tina, Sharjah. Message us on WhatsApp with your area and shade.
Sources
- National Polyurethane Topcoat data sheet (PDF)
- National Paints surface preparation guide, Sec. A-2 (PDF)
All via AEC Online, retrieved 4 November 2026. Quantities are our own calculations. The main image is illustrative.
