Priming after plastering: getting new plaster ready for paint

Why do you need to prime new plaster?

A new plaster layer is absorbent, and not evenly so. Wall paint applied straight onto bare plaster soaks in faster in some places than in others. The result is a patchy wall and a paint layer that does not bond equally well everywhere.

A primer for plaster, also called a fixer or sealer, soaks into the substrate and evens out its absorbency. Paint manufacturers describe the purpose as good adhesion and even absorbency, so that the wall paint can go on top. In our price list this step is called priming. Even beyond new plaster, there are other situations where a wall needs priming.

Paint manufacturers also give a simple test. Spray a little water on the wall with a plant sprayer. If the wall soaks up the water, the surface is absorbent and needs priming.

The same goes for plasterboard. The guideline of the European gypsum industry prescribes a primer under every wall finish, matched to the substrate and to the finish that follows. When finishing plasterboard, that primer is simply part of the job.

How long must plaster dry before you can paint it?

A plaster layer must be completely dry before any primer or paint goes on. Gypsum manufacturer Knauf says that gypsum plaster can be dry enough after about four weeks in good conditions.

Heating can help, but according to Knauf it matters more that the damp air can leave the room, through good ventilation or a dehumidifier.

A thin film layer dries faster. For a whole home we allow 3 to 5 days for application and drying, less in summer, and we can set up heat fans. Traditional plaster is thicker and needs more time. The drying times of plaster and film layers therefore differ considerably from one situation to the next.

Feeling dry is not the same as being dry. A layer that looks dry can still hold moisture; a cool, clammy feel is a sign it is not there yet. Paint over a damp layer traps that moisture, and after a few weeks the paint can lift, blister or discolour.

In new builds the wall itself also still releases construction moisture. That is a reason not to rely on the calendar alone. Anyone who knows why new-build walls still give off moisture will prefer to wait a few extra days.

How do you paint a plastered wall?

Painting a plastered wall follows a fixed order. Each step has its own drying time, and those times add up.

After drying we check the wall. It must be dust-free: if powder sticks to your hand, the primer will not bond properly. We touch up small imperfections before the primer goes on, so they do not show through the paint afterwards.

Then the primer. Our painters work with Sigma paint, such as the Sigmafix Universal primer. According to the product sheet it is intended for, among other things, new plaster and plasterboard, and it can be applied undiluted or diluted up to 1 part in 4 with water, depending on how absorbent the wall is.

According to the same product sheet, this primer is dust-dry after about 2 hours and can be overpainted after about 6 hours, at 23 °C and 50% relative humidity. In a cold or damp room drying takes longer. That is why we schedule the first coat of paint for when the primer is truly dry, not by the clock.

Then comes the wall paint. We allow about 1 day of drying time between two coats. Whether a second coat is needed depends mainly on the colour: with a dark colour or a big colour change, one coat often does not cover.

Can you skip the primer and just add an extra coat of paint?

No, because the two do different jobs. A second coat of wall paint seems to achieve the same thing, but has a different purpose. Wall paint provides colour and coverage; a primer is there to even out the absorbency of the substrate before that colour layer goes on.

If you apply two coats of paint to bare plaster, the wall still soaks up the first coat unevenly. You then pay for an extra coat of paint, while the cause of the patches, uneven absorbency, has not been removed.

The second misconception is that new plaster should be painted as soon as possible. Painting too early traps moisture. It is better to start a few days later than to end up with a wall that stains after a few weeks or where the paint peels.

The third misconception is that priming is only needed in new builds. In existing homes too, a new plaster layer is absorbent, for example after skimming an old wall smooth. The plant sprayer test works the same everywhere.

What does priming and painting new plaster cost?

In our price list, priming appears as primeren. You can have it done separately or in one go together with the painting.

Prices exclude VAT. For renovation work on a home over 10 years old, 6% VAT usually applies; otherwise 21%. The VAT rate is stated in the quote.

If you have a lot of wall area painted at once, the price drops: from 250 m² we deduct € 1.00 per m², from 400 m² € 2.00 per m².

If we also do the plastering, plastering, priming and painting appear together in one quote. Plastering prices always include materials. For the remaining rates, see the prices page.

Who gets your new plaster ready for paint?

With new plaster, what usually goes wrong is the handover between two trades: the plasterer has finished, and the painter turns up too early.

With us, 32 in-house plasterers apply the plaster and 25 in-house painters apply the primer and paint, all from the same team of 97 permanently employed tradespeople. That means we only schedule the painter once the plaster is truly dry, and you do not have to coordinate two separate firms.

If the plaster has already been applied, by us or by someone else, tell us in your request when it was finished and whether it is a film layer or gypsum plaster. The free quote you receive within 24 hours will then already allow for the drying time. At the site survey we check how far along the plaster is.

If the plaster is already there, we can go straight ahead and paint your walls. If it still has to be applied, having plastering done and painting are planned together. And for the rest of the house there is all interior painting work.