Polyurethane is a clear coat that protects surfaces from moisture, water, scratches, and other damage. So, can you apply polyurethane over gel stain?
You can apply polyurethane over gel stain because they have similar formulas. Also, gel stain has high urethane in it, which makes both finish compatible with each other.
Oil-based polyurethane sticks better to gel stain because they use the same solvent (oil).
Gel Stain Dry Time Before Polyurethane
Gel stain must fully dry (cure) before applying polyurethane over it. It takes gel stain 72 hours to cure and 24 hours to dry. This finish has a slow dry time because it uses oil as its solvent and has a thick flow.
For the gel stain to dry, its solvent must evaporate from the coating. However, the evaporation process is slower since it uses natural or synthetic oil as its solvent. Also, it has a thick flow; this slows the evaporation process even more.
For the finish to cure, the solvent must evaporate, and the coating must oxidize. Once the coating oxidizes, it coating becomes hard and rigid, preventing moisture from passing through. The slower the finish dries, the more time the particles have to harden and become rigid. So, the slower the dry time, the stronger the finish is.
If you seal it too soon, the finish will turn stick because the stain coating isn’t hard (rigid) enough to support a top coat. To speed up its drying time, apply thinner coats or increase the evaporation rate.
Types of Polyurethane To Use
It’s recommended to use oil-based, exterior, or spray polyurethane over a stained surface because they use oil as their solvent and are compatible with gel stains.
You can also use water-based, but the adhesion won’t be good. That’s because water-based polyurethane uses water as its solvent, and oil and water aren’t compatible. If you use it, the finish might turn sticky, tacky, or peel off.
To seal outdoor surfaces, use exterior polyurethane because it has more additives that make the sealant more durable than other types of poly.
How To Apply Polyurethane Over Gel Stain?
Applying polyurethane to gel stain is the same as applying it over paints. You must sand and clean the surface and then apply it.
Here are the tools you need:
- A paint scraper
- A paint shield
- A can of spray polyurethane
- Fine-grit sandpaper
- A bottle of white spirit
- A hairdryer (Optional)
Tip: Prep your workspace by covering walls and floors before sealing it.
1. Degrease and Clean the Finish
First, degrease and clean the gel stain coating. This removes oily scum and dust from the coating, preventing good paint adhesion. The finish won’t dry evenly if you don’t clean it.
To degrease (clean) it:
- Apply white spirits over the coating to remove the dirt.
- White spirit isn’t strong enough to remove the coating, so it will remove the dirt only.
- Use a soft brush to wipe off the dirt.
- Remove the residue of the white spirit with clean water.
You can use white vinegar or soapy water as an alternative to white spirits. You shouldn’t use rubbing alcohol (unless diluted) or turpentine to clean it coating, as these solvents are too strong and can remove the entire coating.
2. Sand the Surface
Once the finish is dust-free, sand it. Sanding will remove imperfections and the glossy finish so the sealer sticks better. To sand gel stain, use 320-grit sandpaper.
3. Thin the Polyurethane
Liquid (or normal) polyurethane has a thick flow so you must thin it before applying it with a sprayer, paintbrush, or roller. That’s because getting an even and smooth finish with a thick coating is harder. If you are using spray-on polyurethane, skip this step.
To thin water-based, use water. To thin oil-based polyurethane, use mineral spirits. If you use a spray gun, thin it in a ratio of 4:1 (4 parts polyurethane, 1 part paint thinner). For a paintbrush or roller, thin in a ratio of 3:1.
4. Apply Polyurethane
Once the gel stain coating is cleaned and sanded, apply the thinned polyurethane.
To apply it:
- Use a sprayer, roller, or paintbrush.
- Apply 3 coats of polyurethane.
- Sand between coats with ultra-fine sandpaper. Don’t sand the final coat.
- Remove dust.
- Wait until one coat dries before applying the next one.
- Allow the finish to dry fully (cure) before using it.
Gel Stain vs Gel Polyurethane
Gel stain has a high level of urethane in its formula. The high amount of urethane makes it durable and water-resistant. Because of its formula (make-up), gel stain is often called gel polyurethane.
Both of these two finishes don’t need to penetrate a surface to stick. Instead, they can stay over the top layer and stick there. However, gel stain has a softer finish and enhances the color of the wood. On the other hand, polyurethane is a clear coats that doesn’t have a color.
While gel stain is durable enough for indoor surfaces, you must seal it for outdoor surfaces because it isn’t enough to withstand outdoor elements for too long.
Related Read: Can You Apply Polyurethane Over Tacky Stain?
Applying Gel Stain Over Polyurethane
You can apply gel stain over polyurethane because they have a similar formula (make-up). Also, gel stain contains a high amount of urethane, so both finishes are compatible.
Gel stain is a topical finish that doesn’t need to penetrate the surface to stick. So, the finish will stick over all surfaces. You can also mix polyurethane and gel stain to get a durable and colorful finish. The gel stain has paint pigments that deepen the wood color.
Final Words
You can apply polyurethane to a gel stain coating they have a similar formula and are compatible with each other. But, you must prep its finish before sealing it.
You can also use gel stain over polyurethane because both finishes are topical finishes and don’t need to penetrate a surface to stick. So, they will stick over each other.
