How Long Does Plaster Take to Dry?

If you’re set to embark on a DIY project, a common question you may have is ‘how long does plaster take to dry?’

Knowing the answer to this question will go a long way in ensuring your project is successful and will help you achieve a smooth, long-lasting finish. At Cuthberts of Edinburgh, we regularly help customers across Stratford-upon-Avon with our leading plastering services. In this article, we’ll provide you with a comprehensive guide to plastering drying times to help you avoid cracks and uneven surfaces.

Read on for more information…

How long does plaster take to dry?

On average, plaster usually takes between 3 and 7 days to dry when it is under the right conditions. In some cases, thicker plaster or cooler environments can extend drying times to up to two weeks. While plaster may sometimes feel dry on the surface, it may still have moisture underneath, so it is important to remain patient.

Exact drying times depend on a whole host of factors, including the type of plaster that is being used. This is why no two plastering jobs are ever quite the same.

Factors that impact drying time

There are several factors that influence how quickly plaster dries. By properly understanding these, it can help you avoid common mistakes. These factors include:

• Type of plaster: Gypsum-based plaster dries much faster than traditional types. Gypsum plaster can often be ready for painting within a week, while lime plaster can take several weeks to be fully ready.
• Plaster thickness: Thicker plaster takes longer to dry. While patch repairs will usually dry fairly quickly, full wall or ceiling skims take longer.
• Room conditions: The ideal temperature for drying plaster sits between 15℃ and 21℃. Rooms that are too cold will slow evaporation, while overly hot rooms can cause plaster to dry unevenly.
• Ventilation: Good airflow will allow moisture to escape naturally. A poorly ventilated room will trap humidity, which will likely increase drying times.
• Additives: Some plaster contains additives that are designed to either speed up or slow down drying times. These are usually used in specialist applications.

What happens if plaster dries too fast?

If plaster dries too quickly, it can cause a whole host of problems, including:

• Cracking: Rapid moisture loss will cause plaster to shrink too quickly, causing cracks.
• Shrinkage: Uneven drying can cause plaster to pull away from the surface, weakening the bond.
• Poor finish: Fast drying doesn’t allow enough time for proper trowelling, which can cause an uneven surface.
• Reduced strength: If the plaster dries too quickly, it won’t cure properly and will likely cause damage later down the line.
• Decorating issues: Paint may peel or become patchy if the plaster has dried too quickly.

What happens if plaster dries too slowly?

While slower-drying plaster is safer than rushing the process, significant issues can still occur. This includes:

• Extended dampness: Prolonged moisture can encourage mould problems.
• Weak surface: Plaster that remains damp for too long may not harden evenly, affecting durability.
• Delayed decorating: Decorating when the plaster has not fully dried can cause its own problems.

How to tell when plaster has dried

Before painting or decorating, it’s important that you check the plaster has fully dried. These are the main signs that indicate plaster is ready:

• No damp patches: Fresh plaster is darker when it is wet. Once the plaster has dried, there will be no damp patches on the surface.
• Consistent colour: Fully dried plaster will be a uniform pale colour across the whole surface.
• Feels cold to touch: Dry plaster is often cold to the touch. It will also feel firm and not soft or chalky.

If you’re not sure if the plaster is dry or not, it is always worth waiting a few extra days before decorating.

How to help plaster dry

While you might be tempted to speed up the process, plaster should always be allowed to dry naturally. However, you can make sure the conditions are right for this to happen. This includes:

• Good ventilation: Make sure windows and doors are open to allow moisture to escape gradually.
• Avoid direct heat: Do not point heaters directly at the plaster. This can cause uneven drying and cracking.
• Dehumidifiers: Dehumidifiers are helpful in conditions that are especially damp. However, they should be used gently and not as a substitute for proper airflow.
• Stable room temperature: It is important to maintain a stable temperature in the room. Ideally, this should be between 15℃ and 21℃.

At Cuthberts of Edinburgh, we’re plastering experts and can provide a professional plastering service, including Venetian Plastering, for your next project. Get in touch today to find out more.