How Long Does PVA Take to Dry?
PVA glue, the normal craft glue, has a surprisingly versatile number of uses in home improvements. It tends to take just 20 to 30 minutes to dry, so it is also very easy to use!
However, much depends on the temperature in the property and what you're using PVA (or Polyvinyl Acetate) for.
One of the most common uses for PVA in the trades is in plastering to prime wall surfaces and help the plaster bond with the wall - it literally sticks materials together and is also an effective shield against damp and staining.
Factors That Affect How Long Your PVA Will Take to Dry
In most repair or redecoration projects, it's preferable to use sealants that will dry as quickly as possible so you can move on to the next stage.
As we've mentioned, a thin coat of PVA in a room temperature environment takes about half an hour to dry.
In plastering, it could be more like an hour before the PVA is totally dried through, rather than just touch dry on the surface.
That depends on the temperature, humidity, thickness of the PVA and what you're using it for.
PVA applied to wood will also take longer to dry due to the moisture content naturally occurring in timbers.
Ways to Speed Up PVA Drying Time
There are a few things you can do to expedite the process:
- Improve ventilation - the greater airflow, the faster the PVA will dry.
- Apply thinner layers - smaller volumes of PVA will dry faster than one thick coat.
- Using a fan - a fan, dehumidifier or decorator's heat lamp can all help.
- Combine PVA with water - depending on the application; you can mix PVA with water to achieve your desired solution, which dries quicker than a layer of PVA.
Note that while a warmer room will help the PVA dry out, it's not advisable to use high heat on a PVA surface for extended periods - too much heat can damage the glue if used for prolonged intervals.
PVA can also be used as a mixture, combined with water to seal concrete on poured floors or walls, creating a barrier between the concrete and paint or other materials.
Adhesive PVA coats applied to concrete usually need around 30 minutes to one hour to set, but a full curing time of 24 hours.
Most sealants used in this way come with a two-part mixture, premeasured in the correct quantities to reach the right solution, used to seal cracks and create a moisture-proof seal.
In most cases, it's worth waiting for the PVA to completely set before applying a layer on top, as a seal that hasn't yet fully cured might mean that paint applied on top also won't set very quickly.
However, as we'll explain shortly, it can be beneficial to use thicker PVA concentrations to ensure your mixture remains pliable, giving you more time to complete the application process before the material dries out and becomes rigid.
Uses of PVA in Plastering and Decorating
We've taken a look at some of the typical uses of PVA - but this low-cost liquid glue is probably used in more areas of your home than you might expect!
PVA sealants are strong, supple, and bond with a vast range of materials, with resistance to movement, making them ideal for most properties.
Here are some examples where you might find PVA as a multi-purpose product:
- Timber sealant to protect panels, frames and joints from water damage.
- Waterproof solution for plastering and to ensure the plaster sticks to the wall.
- Primer for render and mortar to improve waterproofing.
- Wood glue for stud work and framing, applied with clamps while drying.
- Cement filler to bond materials and fill small gaps in the mixture.
PVA adheres to paper, textiles, wood and cork among many other materials, so it is a useful bonding product for many different tasks.
Alternatives to PVA Bonding Glue
If you're in a hurry, several other types of glues are also widely used in construction - although some will cost considerably more than PVA and be less widely available.
Polyurethane is a type of wood glue used to fill small gaps and bond plastic, stone, and ceramics. It takes about two hours to dry when clamped and 24 hours to cure.
Epoxy is a combination of resin and a hardener, which is much thicker than polyurethane or PVA. It's commonly used in smaller repairs, is waterproof, and can be drilled or screwed into once dry - rapid-set epoxy is dry in around six hours.
Instant bond is an alternative, which provides faster drying times, with a cyanoacrylate adhesive base, often applied with an activator spray to ensure it dries in seconds, with a tremendous bonding strength.
Benefits of PVA in Home Improvement Projects
One of the most significant benefits of PVA is that it is cost-effective and used in a massive array of tasks, from sticking paper to use as a wood adhesive, used by joiners and carpenters.
As a waterproof glue, primer and sealant, a PVA base can improve the finish of a wall and ensure that materials bond securely.
It's also useful in painting as a primer that creates a sealant to stop old water stains from leaking onto new paint or wallpaper.
Other advantages include:
- Uses in cement and mortar to improve waterproof properties and deliver advanced adhesion to the surface.
- Waterproofing timbers and tiles usually requires around three layers of undiluted PVA in the latter, with each needing to be fully cured before the next coat.
- The colourless finish, which doesn't react with other surface preparation materials or substances.
- Options to combine PVA with sand and cement mixtures to maximise sealant properties without impacting the porosity of the surface, provided the mortar or render is applied while still tacky.
PVA is also great for highly absorbent surface materials, such as plastering over Artex ceilings. The moisture in the plaster means it can be hard to achieve a smooth finish, but a PVA sealant layer slows down moisture absorption to keep the plaster workable.
Anybody can use PVA, and it is applied with a simple paintbrush without requiring specialist materials, equipment or training.
FAQs - How Long Does PVA Take to Dry?
Next, we'll look at some of the frequently asked questions about how long your PVA solution should take to dry and how to ensure you're applying it correctly.
Why Should I Use a PVA Coat Before Plastering an Internal Wall?
You don't have to apply a PVA solution and can plaster or skim directly into a plasterboard panel. However, older plasterboard commonly needs a primer and adhesive layer of PVA to ensure a smooth and even finish.
Dried plasterboard or even brand new panels with a flat surface can be difficult for the plaster to bond with, so PVA acts as a multi-purpose tool to provide better bonding, additional water protection and help the plaster adhere correctly to the wall.
PVA can't cause any problems since it dries clear and doesn't react with other compounds, so if you're unsure whether to use a primer, it's a sensible option.
How Should I Use PVA as a Render Before Plastering?
If you're re-plastering a wall, the best solution is to mix one part PVA to three parts water, applying the mixture to the wall immediately before the skim coat.
The PVA should be given a little time to dry slightly without curing completely, so the wall is still tacky and has a good bonding surface.
How Long Do I Need to Wait For PVA to Dry Before Plastering?
PVA dries like any other liquid - it becomes touch dry fairly quickly but takes longer to be cured, i.e. dried completely through.
Depending on the room's temperature, humidity levels, and the concentration of your PVA coat, it normally takes up to 24 hours to cure - although it can dry much faster with sufficient ventilation.
For plastering, most contractors apply one coat, leave it to cure, and then apply a second coat around one hour before applying the plaster, so they have a double layer of primer, sealant, and adhesive.
How Can I Make PVA Dry Faster?
There are many ways to speed up your drying time, but also important to ensure you wait until the PVA is properly set.
Still, generally, it's as simple as increasing ventilation, turning up the heating, opening windows, directing a fan at the wall, or applying thinner PVA layers each time.
Decorator's heat lamps are often used to help paint dry faster and make the wall workable quicker.
Why is PVA Useful When Plastering?
PVA mixed with plaster is called bonding plaster, which is excellent at bonding to any surface, without needing an absorbent material to adhere to.
You can apply PVA as a bonding material to things like thick concrete blocks or brickwork, where the bonding plaster acts as a scratch coat ready for the decorative layer on top.
References:
- https://cementanswers.com/how-long-does-pva-take-to-dry-before-plastering/
- https://propertyworkshop.com/plasterwork/pva-for-plastering/
- https://guides4homeowners.co.uk/sealant/how-long-does-pva-sealant-take-to-dry/
- https://www.diydoctor.org.uk/projects/pvaadhesive.htm
By Johnny Fuller
Home Improvement editor at NWrenovations.com
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