How Long To Leave Plaster Before Painting?

You want to paint your room, but you don't know if the plaster has dried enough. It's hard to tell when plaster is dry and it can be a costly mistake if you paint too soon. Waiting for plaster to dry can be a pain. We all know that waiting is hard, but it's even worse when you're in a hurry and need to paint your walls.

On average it takes about one-two weeks for plaster to fully cure. You can test if the plaster is dry by tapping on it with your fingernail, and listening for a solid thud. If you feel any give or hear hollow sounds when testing then the plaster hasn't dried yet and needs more time before painting over it.

A word of advice: prepare your walls very carefully before plastering. Make sure that you have removed all old wallpaper and flaking paint before beginning to apply the fresh plaster. This helps the new plaster, which is very heavy, to adhere to the surface and bond effectively.

There are many reasons why this question is not so simple to answer. It depends on many factors such as:

1. How many coats of plaster have been applied?
2. What type of plaster has been used?
3. What type of wall has been plastered?
4. What time of year has the plastering been done in?
5. Where has the plastering been done?
6. What size of the room has been plastered?

And so on….

But does it matter if I paint the plaster before it is completely dry? I mean, what is the worst that could happen?

There is so much conflicting advice available, and it is impossible to give a definitive answer, so I am going to advise waiting at least seven days and then do a thorough inspection of the condition of the plaster.

If the wall was constructed of plasterboard, then it may well be ready to paint. But, if plastering was applied onto bricks or concrete, it could take another two weeks to dry.

Believe me, it will be worth the wait and you will avoid all sorts of unnecessary problems in the future.

Seven Days is such a long time to wait!

There are other things you can do while you wait for the plaster to dry. For example, you can watch as it dries and changes color. When all the damp patches have dried and it has become a beautiful dusty pink color all over, you will know that it is ready to be painted.

So many people actually love this color that Farrow & Ball, the famous U.K. paint brand have created a paint color that is named “Setting Plaster”.

You should also make sure that the room, where the plastering has been done, is well ventilated. Natural ventilation is best, as letting the plaster dry at its own pace will prevent problems like cracking, which occurs when the plaster has dried too quickly.

Of course, if you choose to have walls plastered in summer, warm temperatures will speed up the drying process, and you might be able to shave a little off the waiting time.

I do not advise the use of dehumidifiers to reduce the drying time of plaster. If plaster dries too quickly, it will crack and you will have to deal with an uneven surface.

Another good reason for allowing the plaster to dry naturally before painting is dampness. Painting on damp plaster could trap moisture between the plaster and the paint, and this prevents the moisture from evaporating. It will eventually cause mold to multiply. Mould is very dangerous if inhaled and will not look pretty on your wall. It is a very costly and difficult problem to deal with.

Prepare a Mist paint

You will need to be prepared to apply a mist coat to the dried plaster before you begin painting and this is an essential step in attaining a perfect finish for your newly painted wall. 

It is possible to buy new plaster emulsion, but they are expensive and not absolutely necessary. You can make a mist coat very simply by diluting some basic emulsion with water – 4 parts water to 6 parts emulsion. It should preferably be a light-colored emulsion that will not be visible through your final choice of paint color. 

Some people give two coats of mist paint, but that is not absolutely necessary. Always give the mist paint plenty of time to dry too.

There are times when you just can’t wait to paint

If for some reason, you are in a terrible hurry to get the walls painted, there are Microporous paints available. Check out the range at www.amazon.com and be sure to follow the manufacturer’s instructions.

 I must warn you that this is a more costly route and you are most likely to be disappointed with the finish of the paintwork if you do not let the plaster dry out naturally. 

According to Jeff Howell, a writer for The Telegraph newspaper, “As for microporous, it may be another case of something we see often in the world of building – a scientific-sounding term that is not as wonderful as it first seems.”

BUT WAIT! What if you don't have time?

Well, there are a few things you can do that will help speed up the process:

• Use A Dehumidifier In The Room
• Turn the Heating Up In The Room
• Use a Hairdryer to Quickly Increase Airflow and Speed up Drying Time
• Use Fans to Draw Circulating Warm Air Around Rooms or Hang It From Ceiling If You Have Enough Space
• You can also use an air conditioner in reverse. Use it to suck hot, humid air out of the room.

You won't have to worry about plaster drying anymore if you do one or more of these things!

To sum up:

This is not a project to complete in a hurry. It will be worth the wait when you see your beautifully smooth walls painted in your favorite color. Allow the plaster to dry naturally, in its own time, however long that takes!