Marine aluminium paint coverage calculator
Litres of paint and number of cans for a given area, film thickness and number of coats — with the substrate preparation note that decides whether it lasts.
Area
Product
Volume solids tells you how much of the wet paint stays as dry film. The rest evaporates, which is why you always buy more litres than the dry film volume suggests.
Spread rate (m²/L) = VS% × 10 / DFT (µm)Litres per coat = Area (m²) × DFT / (10 × VS%)Total = litres per coat × coats × (1 + loss%)
| Marine coating layer | Typical DFT |
|---|---|
| Pre-treatment primer (wash or etch) | 5 – 15 µm |
| Anti-corrosive primer | 40 – 80 µm |
| Build coat | 80 – 150 µm |
| Antifouling (not for aluminium) | — |
| Total system | 200 – 350 µm |
- Abrade or blast, then prime within 4 hours — aluminium oxide re-forms fast and paint bonds poorly to it.
- Budget 15–25% loss for brush and roller, up to 40% for spray on frames and brackets.
- Aluminium needs 50–100 µm more film build than GRP for the same service life; cutting film thickness is false economy.
People also ask
Why can I not use normal antifouling?
Most antifouling contains copper, which is strongly cathodic to aluminium. On an aluminium hull it accelerates corrosion instead of protecting it. Use a copper-free product specified for aluminium substrates.
What is volume solids and where do I find it?
It is the percentage of the wet paint that becomes dry film. It is on the technical data sheet for every marine coating, usually as “volume solids” or “VS”.
How thick should a marine coating system be?
200–350 µm total dry film for an immersed aluminium hull, built up in two or three coats. The splash zone usually gets extra film.
Do I need a primer on aluminium?
Yes. A wash primer or etch primer creates the chemical bond that the topcoat alone cannot make on an oxidised aluminium surface.
How long before launching?
Follow the data sheet — typically 7 days at 20 °C for a full system. Launching early is one of the most common causes of coating failure.
Does anodising replace painting?
No. Anodising is a thin oxide for appearance and light corrosion resistance. Immersed structure still needs a proper coating system or cathodic protection.
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