So, you have taken the time to carefully and lovingly apply plaster to a wall or ceiling, and understandably you are itching to finish the job and add a lick of paint. You’ll have to be a little patient though, as painting over wet plaster before it has had a chance to set can create a lot more work for you in the longer term.
How Long Should I Wait Before Painting Plaster?
How long is a piece of string? The period of time that fresh plaster needs to dry varies from surface to surface, with circumstances such as the temperature of the rooms in question and the size of area covered.
You may well find that it takes up to six weeks before your plaster is fully dry and ready to for paint to be applied, and that’s just a conservative estimate.
If you apply multiple levels of plaster, you could be looking at upward of two months. You’ll be able to tell when the plaster is beginning to dry as the deeper colours will start to fade to the naked eye – don’t rely on touch, as you could damage or stain the plaster surface by doing so.
What Happens if I Paint Over Plaster Before it’s Dry?
In a word, damp – every homeowner’s nightmare. If you add paint to plaster that is still damp – and remember that could take several weeks – you will be trapping moisture into the wall of ceiling by applying a skin over the surface.
This skin will prevent the moisture from escaping to the atmosphere and harmlessly evaporating, and as a result it will seep into the surface. This will, in turn, generate mould – hugely dangerous to breath in, as well as being extremely unsightly – and eventually turn to damp.
As anybody unfortunate enough to deal with damp in the home will be able to advise you, the effort and costs incurred in dealing with this problem are considerably more frustrating than having to wait a few extra weeks to apply some paint to a wall or ceiling. What’s more, with no moisture you will find that the paint you have applied flakes and falls off the surface quickly.
I Can’t Wait That Long – Do I Really Have No Other Option?
If you absolutely must seek a shirt-term option and are prepared to pay a little extra for your trouble, you can head to a DIY shop and purchase some microporous paint.
This specialist product is designed to allow surfaces to breathe after application, meaning that it will repel unwanted water stains (such as rain on an outdoor surface), but avoid trapping water once you have painted over fresh plaster.
However, be aware that microporous paints are considerably thinner than a standard application, which means that you will need several coats before you notice a difference – and you’ll still need to paint over the plaster once again with emulsion once it is fully dry.
I’ll Wait for the Plaster to Dry – is There Anything I Can Do to Speed Up the Process?
The warmer the room temperature, the faster the plaster will dry. If you are applying a coat of plaster during the summer months, leave the windows open if you are indoors, or during the winter, turn on the central heating if that is an option – unless the radiator is located very close to the plastered surface, as this could cause cracks.
It is not advisable to plaster an outdoor surface during the cold season due to the risk of weather damage.
Preparing your surface will also help – plaster will rarely stick to an uneven surface, or one that still holds scraps of wallpaper. Ensure your work area is smooth, and keep the plaster extremely clean as you are applying it. You’ll probably need to apply more than one coat too, so don’t panic too much about getting it perfect first time. Finally, do not over-polish the finish – your wet plaster should have an eggshell surface and appearance, but remain even.
Should I Seal My Plaster Before I Apply Decorative Paint?
Yes, for your protection you should definitely do so – although it is imperative that you use the correct product for this, and that you avoid doing so while the plaster is still wet, unless you are using microporous paint.
You can purchase a specialist item for this from any DIY shop, which is usually made of PVA solution, or if you have are confident in your painting abilities you can use a light shade of any water-based emulsion paint (this is typically a more cost-effective solution).
Apply this sealing coat, which is also sometimes referred to as a mist coat, apply filler to any areas that may require the attention of such a product, and then paint over your plaster with the colour that you intend to retain.
I Accidentally Painted Over Wet Plaster – What Can I Do?
Unfortunately, you cannot do anything about this until you have given the surface a prolonged period of time and see what the results are.
The plaster may dry itself out and you may get away with it, or the result may appear stained or inconsistent in colour and tone, the paint may crack and peel, or you may experience a musty, damp smell as the surface is unable to breathe. If any of this happens, take a sander to the wall and start again – though be sure to check that the wall itself is not damp as a result.
It’s Been Weeks and My Plaster is Still Damp – Did I Do Something Wrong?
Be patient – it could be upward of two months before the plaster is fully dry.
Do I Need a Professional Builder or Painter and Decorator to Apply My Plaster Before I Paint it?
No, not if you are reasonably confident in your DIY abilities and competent in such tasks. Obviously, there is nothing to stop you from hiring a tradesperson to do the work for you, but don’t feel that you have no other option if you’d like to try to task yourself. Again, be patient and wait for it to dry before you start to apply paint.
Do I Need to Use Particular Plaster or Paint Around Heat Sources Such as Wood Burners?
Not if it’s dry, as traditional plaster is highly heat resistant. However, if your stove is located close to the surface that you have worked on then resist lighting the fire for a while, otherwise you may crack the plaster while it is still setting.
Is Plaster Better Than Drywall? I’m in a Hurry.
Drywall is a faster process and much cheaper, but a plastered wall will be more durable and easier on the eye. As always, it depends on your personal priorities.
Should I Re-Plaster a Damp Wall, or Can I Just Paint Over it?
Applying plaster can be a great way of re-rendering a wall that has suffered with damp in the past, but be sure to use a plaster with a cement or sand backing in this instance. Also ensure that you have primed and prepared the wall accordingly, rather than applying plaster straight to a damp surface – this is just making more labour for yourself as it will need to replaced again before long. Consult a professional for advice if necessary.