The length of time plaster takes to dry is determined upon a number of factors such as whether you used plasterboard or backing plaster, temperature, humidity, number of layers applied and so much more. Although obvious, you can’t paint or wallpaper plaster when it’s wet because it can cause adhesion problems and simply be a waste of your time.
During our time of renovating properties, we normally plaster each room and we have plenty of experience regarding the drying of plaster. As you can see in the above image of plaster beginning to dry, wet plaster looks like an “earthy”/brown colour whereas dry plaster is much lighter and is best described as a creamy pink colour.
Although undecorated plastered walls and ceilings aren’t great to look at, it’s worthwhile waiting for it to dry properly to avoid any issues. To provide you with all the information you need to know regarding the drying of plaster, below we walk you through how long it takes, how to speed up the drying process, potential issues and our own case study.
Why Do You Need To Wait?
As briefly mentioned above, failing to allow plaster to dry can cause adhesion problems. For example, if you were to use emulsion paint on wet plaster, it won’t bond properly and end up peeling away. A similar issue will arise if you wallpaper straight onto new plaster that’s yet to dry because the wallpaper paste won’t bond with the wall.
How Long Does Plaster Take To Dry
From our experience, freshly plastered plasterboard can take 2 to 3 days to dry. However, if you’ve plastered onto backing plaster, it can take twice as long to fully dry. Other factors that affect the time it takes for plaster to dry include the layers of plaster applied, time of year, whether the central heating is on, humidity and the quality of the mix.
However, even if it has past the 2 to 3 day period of waiting for the plaster to dry, it’s advised that you visually check the plaster itself. Before painting or hanging wallpaper, you’ll want to ensure there are no dark patches whatsoever. If possible, waiting at least a week for plaster to dry before decorating is recommended (as long as there is no dark patches as shown in the image).
How To Speed Up The Drying Process
If you are working to a tight schedule or simply can’t stand looking at wet plaster any longer, there are methods you can use to speed up the drying process. One of the most effective methods is to use a dehumidifier in the room. However, you should do this with caution (i.e. use a low power setting) because drying the plaster too quickly can cause cracking.
The best method that we would highly recommend is to ensure the room has plenty of ventilation (i.e. slightly opening the windows) as well as a low background heat.
However, it’s important to note that if you are too impatient and rush the drying process of new plaster, it may cause issues that you’ll certainly regret later on.
What Does Dry Plaster Look Like? (Before & After Results)
As you can see from the above photos, the plaster becomes much lighter in colour overtime, which is a good indication that it’s drying. In this particular case study, we had the windows slightly open and as it was plastered during the summer, it meant that there was enough heat for it to gradually dry. However, before we began painting the new plaster, we left it to dry for another few days for complete peace of mind.
If you are unsure what dry plaster looks like, we refer to it as a creamy pink colour as opposed to an “earthy”/brown colour. Unless you have issues with damp (as discussed below), you should begin to see patches of dry plaster appear after 24 hours. These patches should then begin to increase in size overtime until all of the plaster is dry.
Why Does Plaster Crack When Drying
If the plaster is beginning to crack whilst it’s drying, there are a few reasons why this may be happening. The first and most common reason is that too much heat is being used in an effort to speed up the drying process of fresh plaster.
Other reasons why the plaster is starting to crack can be due to the fact that not all of the wallpaper was removed prior to being plastered over, an incorrect PVA ratio was used in the mix and even using out of date products. If you have a bad case of plaster that’s cracking, we wrote a guide that lists all the reasons why plaster cracks.
Why Isn’t The Plaster Drying
If you have waited over a week and there is no signs that the plaster is drying, you may have a problem. There could be penetrating damp or a leak that needs investigating further.
Plaster will always dry naturally but if it remains wet with obvious dark patches, this may be a sign that there is an issue that needs fixing rather than forcing it to dry with heat.
Hopefully the above guide on how long plaster takes to dry covers everything you need to know. Although it can be frustrating to look at plaster for a week or so before you can begin decorating, it’s strongly advised that you do so. The last thing that you want to happen is for all of your hard work of decorating to begin peeling due to the plaster not being fully dry. If you have any question relating to the drying process of plaster, feel free to get in touch with our team.