How many coats of paint does a wall need?
In most cases, two coats of paint are enough for a wall to be well covered and an even colour. One coat is usually enough only when you are changing to a colour very similar to the one you had. For big colour changes, or on new walls, you may need three.
Why one coat is almost never enough
A coat of paint is a thin layer. It does not completely cover the old colour and it lets small differences in the wall show through. When it dries, the first coat can look uneven, with roller marks or lighter and darker patches. The second coat evens everything out.
If you try to cover with a single very thick coat, the result is usually worse. The paint runs, leaves marks and takes longer to dry. Two thin coats are better than one heavy one.
When two coats are enough
- Repainting in the same colour, or a similar one.
- Going from one light colour to another light colour.
- A wall in good condition, already painted and well prepared.
- Good-coverage paint, applied with a suitable roller.
When you may need more
In some situations it is wise to allow for an extra coat:
- Going from a dark colour to a light one. A primer helps save coats.
- Strong colours, such as intense reds and yellows, which tend to cover less.
- New walls or walls with many repairs, which soak up a lot of paint in the first coat.
- Low-quality or heavily thinned paint.
In these cases, a coat of primer before the colour can reduce the number of finishing coats. To work out how much you need, look at the tin: most paints state the area they cover per litre and per coat. Check this figure, because it varies from paint to paint and from wall to wall.
Waiting time between coats
Each paint has its own drying time. In general, water-based paints become touch-dry sooner and can be recoated after a few hours, but the correct time is written on the packaging. Stick to it. If you paint over a coat that is still wet, you can drag the paint and leave marks.
Drying time also depends on the weather. On humid days, or in rooms without ventilation, paint takes longer. In homes near the sea, or in the Sintra area, where the air tends to be more humid, it is worth allowing extra time.
How to tell if it looks right
Once the second coat has dried completely, look at the wall with light coming from the side. If you see patches of a different colour or the old colour showing through, you need another coat. If the colour is even, you are done.
Do not judge the colour while the paint is still wet. Almost all paints look different while they dry.
Tip: Calculate the paint on the basis of two coats, even if you only intend to apply one. There is always some left over for touch-ups, and you avoid running short halfway through the job, which can cause differences in shade between tins.