Plywood can be a tricky material to work with, especially if you don’t know how to seal it well. There are many options for this task, including varnish, tung oil, and paint. But for this post, I will discuss sealing plywood with PVA the right way.
Using PVA glue as a sealer isn’t the most common choice, but it will work when done right. It can be your alternative when working on plywood, and no other sealer is available right away.
What is PVA, and how does it work?
PVA stands for polyvinyl acetate and is often available in glue format. It’s a thick and rubbery polymer that possesses top-notch adhesive characteristics. In addition, it’s non-toxic and often colorless, which you can find in every hardware store.
Moreover, PVA is a widely used component among glue products. It’s also called wood glue, school glue, carpenter’s glue, or Elmer’s glue in the United States.
While you can use Elmer’s glue straight from your child’s school bag, industrial-grade PVA is quite different. Elmer’s glue has been formulated for minor adhesion, so it tends to get brittle over time.
If you’re planning to seal plywood using PVA, you should get one made for woodwork. This has better adherence and resistance to wear and tear.
Benefits of sealing plywood with PVA
With all the sealing materials you can use, you’re probably wondering why we’re talking about PVA. To answer that, here are some of the benefits you’ll get when sealing plywood using this substance:
- No nasty fumes. Unlike varnish or thinned tung oil, PVA doesn’t emit volatile organic compounds. As a result, it’s safe to use on plywood that will be installed on living areas or food preparation areas. This also means that PVA doesn’t have an awfully strong odor.
- Clear color. PVA glue dries with a clear color, so it won’t be an eyesore in case you want to retain the plywood’s original appearance. This also makes painting the plywood much easier.
- Remains flexible. Unlike other glue materials that become brittle over time, PVA retains its flexibility. This means the plywood will remain sealed for longer periods.
- Non-toxic. Unless you’re going to swallow the PVA glue, it won’t be toxic. You can safely use the sealed plywood in food preparation areas.
- Strong adhesion. Woodworkers use PVA to join two wood pieces. It also works well as a sealer since it clings to plywood very well.
- Water-resistant. PVA glue is highly water-resistant that’s why it can hold wood well even if it’s exposed to moisture or wear and tear.
How to seal plywood with PVA
PVA is mostly used as an end grain sealer, though it will still work as a face grain sealer based on your preference. Here are the basic steps to follow in sealing plywood using PVA:
Step 1. Prep your plywood
The first thing you need to do is make sure that the plywood is clean and doesn’t have any dust or dirt. You should use a lint-free cloth to wipe the wood before you move to the next steps.
Step 2. Dilute the PVA glue
Next, you need to dilute your PVA glue. This substance is quite rubbery and difficult to apply.
You can dilute the glue with some water at a proportion of 5 parts water with 1 part glue. You can increase the amount of glue based on how porous the material is.
The rule of thumb is that porous wood requires more glue, just like in the case of plywood. With this, a 1:1 proportion is the ideal choice.
Step 3. Apply it to the plywood
Once the PVA glue is diluted, you can start applying it on the edges and surface of the plywood. Keep it thin to prevent making the plywood water-logged.
You can use a synthetic bristled brush for this application. It’s easier to clean, and the bristles won’t become too soft as it absorbs water.
Step 4. Let it dry
After the first coat, you should let the PVA glue dry. Depending on the level of dilution, this will take you anywhere from 2 to 4 hours or as much as 24 hours. Patience is key here if you want a plywood seal that will last for a long period.
Step 5. Apply more as necessary
You can re-apply more PVA coatings to your plywood as necessary. Three to five coatings should suffice for most applications as you wouldn’t want the surface to feel gummy or rubbery.
How long does it take for PVA to set?
PVA glue could take as long as 24 hours to fully set. Of course, this depends on the PVA glue product you used, your level of dilution, and the humidity in your location. Nonetheless, it’s crucial to give PVA glue the time to dry and set for the best results.
How can I speed up PVA glue drying?
If you’re a bit time-constrained, there are a few methods to speed up the drying of PVA glue.
First, you can use a small fan toward your workpiece to help evaporate the water you used for dilution. You can also place the sealed plywood in a warm and dry place. Running a dehumidifier will also work as it will collect the airborne moisture, which slows down the drying process.
Aside from that, some woodworkers will use the oven in a warm setting. However, this is only possible for small plywood pieces and if you’re willing to take some level of risk.
How long does PVA last?
On the container, PVA glue usually has a shelf-life of one year in terms of topnotch quality. After that, the glue ingredients will start to have chemical changes that will affect how well it seals or adheres to plywood materials.
When applied to wood, PVA can last for two to three years, depending on the level of wear to which it will be exposed.
Can you paint over the PVA sealer?
Once the PVA glue dries, you can paint over it with no problem. The PVA will bond well to wood, so it wouldn’t interfere with how well the paint will set.
I also recommend sanding the PVA seal a bit using high-grit sandpaper. This is to remove any rough or uneven parts as well as to create added traction for the paint.
Can PVA be used as a wood primer?
Yes, you can use PVA as a wood base primer. It penetrates the wood grain well and will adhere to it strongly. In fact, PVA has unbeatable adhesion even to metal, masonry, and old paint. It’s a very versatile substance that also works as a sealer and glue.
Do I need to apply PVA to the plywood before painting?
PVA can be used as a primer to the plywood before you paint it. A diluted solution of PVA glue can be applied up to three coats before performing the paint job. It’s crucial to let each coating dry before applying the paint so that it won’t mess with your coatings.
Nevertheless, you can always skip PVA as the paint will still adhere to plywood well. Also, you have to be careful because improperly applied PVA can result in a sticky finish.
Can you waterproof plywood with PVA?
PVA has excellent waterproofing characteristics. It bonds well and creates a tight seal on the material.
For the best results, you should dilute your PVA glue with water. This may sound counterproductive when trying to create a waterproof finish, but it’s necessary to allow the glue to soak on the wood pores before drying.
What does PVA glue not stick to?
As much as PVA glue has strong adhesion, it only does so on porous materials like wood and paper. On non-porous items like plastic or metal, it would have a less strong bond, especially if the surface is smooth.
What’s the difference between PVA glue and white glue?
PVA glue is different from the white glue used in school crafts, though the latter is also a type of PVA-based glue.
However, the difference is that pure PVA glue dries fast and creates a solid hold on the material. Due to this characteristic, PVA glue is more expensive than white glue.
Also, white glue will become brittle and weak when exposed to moisture. In comparison, PVA glue remains water-resistant for a long period of time.
Sealing plywood with PVA is a good way to protect the material from moisture-related damages. When done right, your plywood will last long, even if exposed to various elements. Overall, PVA is a cost-efficient and convenient alternative if other sealers aren’t readily available.