How Long Does it Take for Plaster to Dry? – Plaster Drying Questions
Plaster drying time is one of the most important factors to consider when plastering your home. How long it takes plaster to dry affects the time frame for finishing your renovation project, as it can delay the application of additional layers and painting of the plaster.
Your plaster must be completely dry before you begin any decorating. The plaster will need a minimum of 3-5 days to achieve full dryness, but for some jobs, it may take up to 4 weeks. Once it’s dried, the plaster will appear pale pink, and any previous brown patches will have disappeared. Not allowing the plaster to dry sufficiently can also harm the quality of the finished job overall. This is why an extended period of time is recommended before moving on to your next step; for example, painting. So, we decided to look at all the details concerning plaster drying and the transformation of your home.
How Long Does it Take Plaster to Dry?
For a freshly plastered wall to be completely dry, it can take up to 4 weeks, sometimes even more. How quickly the plaster dries depends on several factors, including:
- The number of layers of plaster
- The thickness of each plaster layer
- If it’s applied over backing plasterboard
- How humid the air in the room is
- The season, weather and temperature
- The material used for the plaster
A plaster’s drying time is also referred to as the plaster curing time.
Plaster Drying Time by Type of Job
Given the correct humidity and temperature levels, usually, plaster jobs should dry within:
- Small patchwork and repairs: 1 week
- Plaster on plasterboard for whole walls: 2 weeks
- Multiple layers of plaster per wall: up to 4 weeks
However, if you are plastering in the cold, wet part of the year, increased humidity can double the plaster drying time.
Plaster Drying Time by Type of Plaster
The type of material you use when you plaster a wall also influences the drying time. Here’s a rough estimate of the drying time for some of the most popular plaster types:
- One coat plaster – 3-4 hours
- Browning plaster – 2 hours
- Bonding plaster – 2 hours
- Hardwall plaster – 1.5-2 hours
- Multi-Finish plaster- 1-1.5 hours
- Board Finish plaster – 1-1.5 hours
- Thistle Multi Finish plaster – 2 hours
How Long for Skimmed Plaster to Dry?
Newly plaster skimmed walls take approximately 4 days to dry out before you should attempt to decorate them. It is crucial to wait until the plaster has dried, and its colour has changed to a pale pink. There should be no brown patches as a guide. In some instances, you may need to wait up to 4 weeks.
How Long Does Bonding Take to Dry?
Your bonding plaster will be dry and ready for a finishing coat after 24 hours. Apply this beading and plastering technique to tackle challenging areas like boxed-in pipes, windows, and external edges.
How to Speed Up the Drying Process
Plaster drying is a chemical reaction caused when the compound comes into contact with water. Removing the water earlier can halt this reaction, threatening the plaster’s structure and causing hairline cracks. So when it comes to answering how to dry plaster quicker, you can open the room’s windows, and door as doing so will increase the airflow and ventilation, allowing moisture to escape.
Can Radiators or Dehumidifiers Speed Up the Drying Process?
It may be tempting to place dehumidifiers in a room with wet plaster. However, this can have disastrous effects. You should never use a dehumidifier in a room with wet plaster. In cold, damp rooms, perhaps in winter. Using a radiator or any heat source should be avoided as this can cause the plaster to dry too quickly and cause it to crack.
Why You Must Wait for Plaster to Dry
Waiting for plaster to dry can feel like a chore, but it is essential. Moisture causes damp patches and mould. Plus, in some cases, it can result in efflorescence, otherwise known as salting. So it must dry.
Paint will seal the walls, preventing moisture from evaporating from the plaster. So if you intend to paint the wall, leave it to dry.
Painting on Plaster
The main reason why people want to know how long it takes for plaster to dry is that they would like to repaint the walls to get the finished look they are after. Annoyingly, it takes as long as it takes.
Always allow a minimum of a week before you paint over fresh plaster to ensure it is completely dry. As we said before, sometimes, in combination with wet weather conditions, you may need to wait even a month to paint your walls. It may sound like a lifetime, but the wait will be worth it.
What Happens If You Paint on Wet Plaster?
If the plaster is damp when you start painting over it, it can cause a whole list of problems, from uneven colour and dark patches to peeling and cracking paint. It can even lead to dampness getting trapped into the wall and damaging it over time.
How to Paint on New Plaster
Follow these simple tips to paint effectively over new plaster.
1. Leave the Plaster to Dry
Painting on wet plaster risks dampness and structural damage to the wall.
2. Mix Your Mist Coat
A mist coat prepares the wall for paint. You typically need three parts of paint and one part of water, although you should check your paint tin as different manufacturers require different ratios.
3. Apply a Mist Coat
Mist coats are different as they can drip easily. Using a roller is the quickest option but causes messy splatters. Using a paintbrush will take longer, but you will not have to handle as many drips.
Always move in upward strokes to spread the mist coat evenly and quickly catch and go over any drips to preserve your finish. Then leave the coat to dry entirely.
4. Apply a Top Coat
After the mist coat is dry, you can paint a top coat as usual. Spread it evenly for the best finish. You may need to apply multiple coats.
How to Prepare Your Plaster for Paint?
Once your plaster is dry, you should complete a few crucial steps before painting the surface.
Sanding Down Imperfections
If you are painting over small areas of repair work, you need to sand over the plaster to create a level surface. Use 150-grit sandpaper to smooth the rough areas, then remove the dust with a damp cloth. Ensure the cloth is not too wet, or you risk re-wetting the plaster.
Sealing the Plaster
You must seal the plaster if you want to paint on it, or the paint will run through the plaster. You can use one of two substances: a mist coat or a primer.
Mist Coat
A mist coat is a watered-down coat of white emulsion applied before the main layers of paint.
Primer
Primer, also often called sealer, is similar to paint.
Many contractors will talk about using PVA to seal walls. However, you can only use it in certain scenarios, so avoid using it.
All About the Mist Coat
Whether you use high-end plaster paint or normal paint, applying a mist coat onto the plaster before painting is always a good idea.
The mist coat is the first layer of paint thinned with water to a milky consistency. It’s created by diluting a water-based emulsion and can be applied using spraying, a paintbrush or a roller. It prevents the paint from bonding with the plaster and keeps the paint sitting on top.
You only need one layer of mist coat before applying your normal emulsion, which should be applied in 2-3 layers. In terms of the mist coat drying time, you should leave the mist coat for 24 hours to allow it to set perfectly. When it comes to home renovations, patience is key.
What If You Do Not Apply a Mist Coat?
Dry plaster is incredibly porous, with tiny holes that allow moisture to filter through. The mist coat prevents moisture from being sucked out of the paint. Without it, paint can dry too quickly, and even though getting the process done and over with may sound like a good thing, it’s not. If the paint dries too fast, it can crack and have an uneven and unprofessional appearance.
Hiring a Professional Plasterer
If you are not confident about how to plaster a wall, hire a professional plasterer to do the job. That way, you won’t have to worry about making mistakes with the plaster drying time, mixture or application. AB Drylining can help you with professional plastering and dry-lining services in Wiltshire, Bristol, Swindon and neighbouring areas. Contact us today for a free quote.
How can you tell if the plaster is dry?
The main telltale sign is a colour change. Wet plaster is darker with shades of brown or red, whereas dry plaster is pale, creamy pink. You are looking for an even colour. Dark patches indicate moisture.
How can you make plaster dry faster?
Directing a few heaters towards the newly plastered wall may seem like it will help the natural drying process. However, rushing the plaster drying time is not advised because such interventions could damage the plaster. Opening a window for better ventilation is a good way to speed up the drying process without risking the quality.
What happens if you paint plaster too soon?
If the plaster is not fully drying, painting over it would trap moisture under the paint layer, which could then cause the paint coat to flake and deteriorate quickly.
Can I paint straight onto new plaster?
Adding a base coat between the plaster and the paint is better than painting onto new plaster. If you do want to paint straight onto the plaster, use a special plaster paint specifically designed for this.
What happens if you don’t mist plaster?
The paint will likely start flaking sooner if no mist coat is applied.
The plaster is not drying. What could have gone wrong?
Usually, when plaster takes too long to dry, it is due to a damp issue. Moisture gets trapped in the wall and does not allow the plaster to dry. You may need to call a specialist to take a look and assess the problem.
