Polyurethane is widely used over different types of stains due to its thick and water-resistant finish. But can you apply polyurethane over the gel stain? Here is the answer to that.
Polyurethane can be used over gel stain. This is because polyurethane and gel have a similar make-up. Gel stain is also called gelled polyurethane due to the high amounts of urethane in it.
Also, polyurethane is usually an oil-based sealant and oil-sealants can be used over glossy topcoats like gel. Oil-based sealants like polyurethane are specially designed for glossy topcoats like gel and latex hi-gloss stains.
So polyurethane will stick to the gel stain as long as the gel stain is properly prepped.
So how do you prep gel stain for polyurethane application? Also, how long should you let the gel stain dry before applying the Polyurethane? This post reveals the answers to these questions and more. So let’s dig in.
Also, watch out for helpful tips in this article.
How Long Should Gel Stain Dry Before Polyurethane?
You should allow the oils in the gel stain to evaporate before applying polyurethane over it. Gel stains take longer to fully dry and can take over 3 days to properly cure. On average, most gel stains dry enough for polyurethane application in less than 24 hours.
The gel is a very thick stain. This is because the gel paint has a lot of chemicals and paint particles in it. The high level of paint chemicals is to makes the gel finish very strong. Strong enough to be a protectant (or topcoat itself)
The strong finish produced by gel stain makes most painters and DIYers think the gel stain doesn’t need a protectant (or topcoat) like polyurethane. In all honesty, the gel stain will still be very durable without a sealant or protectant. However, the finish wouldn’t last as long as gel stain sealed with polyurethane.
On average, unsealed gel stain lasts on walls for less than fifteen years. On furniture that is used a lot like tabletops and drawers, gel stain doesn’t usually retain its brilliant stain for over 10 years. However, gel stains sealed with oil-based polyurethane can last several decades.
But the gel stain has to completely dry before you can apply polyurethane over it and this will take a few hours. This is because gel stain is oil-based and oil-based stains take hours to dry.
So how do you apply polyurethane over gel stain? Let’s find out.
How To Apply Polyurethane Over Gel Stain (Made Easy)?
Applying polyurethane over gel stain is just the same as applying polyurethane over oil-based or latex paint. Only with a bit more scraping and sanding.
To apply polyurethane over the gel, you’ll need a few tools:
- A paint scraper
- A paint shield
- A can of spray polyurethane
- Fine-grit sandpaper
- A bottle of white spirit
- A hairdryer (Optional)
Here is a quick rundown of how to apply polyurethane over gel stain:
- Degrease and clean the gel stain
- Sand lightly and remove dust
- Thin the Polyurethane (for non-spray polyurethane; the brush on kind).
- Apply coats of polyurethane on the gel stain
- Dry the finish.
Now roll those sleeves and let’s get to work.
Tip: Ensure to prep your workspace by covering walls and floors before spraying polyurethane.
1. Degrease and Clean the Gel Stain
The first step is to degrease and clean the gel. This helps to remove oily scum and dust on the gel that will prevent good paint adhesion. If the grime is left on the gel, the polyurethane finish will not come out smooth.
To degrease the gel stain, apply white spirit on the gel. White spirit has a very low level of alcohol. This means it isn’t strong enough to remove gel stain so it can be used on gel stain safely. Other products to use include white vinegar and dish soap.
For stronger solvents like rubbing alcohol, ensure to dilute the solvent properly before using it on the gel stain. This is because strong solvents like rubbing alcohol and turpentine can blur or remove wax paints.
2. Sand Lightly and Remove Dust
Using very fine sandpaper, sand the gel stain lightly. This is to buff the gel stain so the polyurethane can stick well. As explained earlier, gel stain is commonly used as a sealant, and as such the stain when dry forms a thick gloss.
This gloss is slick and it’s also impermeable so polyurethane will not sit properly on it. The gloss needs to be lightly sanded first. Then the polyurethane coating can be applied. Use sandpaper with grits from 320 and above to sand the gel stain.
3. Thin the Polyurethane (for non-spray polyurethane; the brush on kind).
This step is only for liquid or the non-spray type of polyurethane. This is because liquid polyurethane can’t be applied directly to the gel stain. Liquid polyurethane has a very thick consistency and it will be very difficult to achieve smooth application if it’s not thinned.
To thin the polyurethane, use mineral spirits. Just add a few drops of mineral spirit into the Polyurethane. Remember, you are just trying to thin the paint or make it lighter so it’s easier to apply. So don’t add too much paint thinner.
4. Apply Coats of Polyurethane On the Gel Stain
You need 3 coats of polyurethane on the gel stain to seal it. While applying polyurethane, ensure to apply in thin coats. This is because thick coats of polyurethane will turn yellow quickly. This is because of the large volume of paint chemicals and oils in each coating of polyurethane.
Spray the first coat of polyurethane on the gel and leave it for a few hours before applying the second coating. Oil-based polyurethane dries enough for re-coat 2-3 hours after the first coating was applied.
When the first coating dries, you need to sand lightly. It’s advised to sand between coats of polyurethane to improve the smoothness of the finish.
Sand the first coat of polyurethane with ultra-fine sandpaper. After sanding, remove the dust and apply the second coating. Then let that dry. After, sand and then apply the final coat. The final coat should be applied as smoothly and thinly as possible. You don’t sand the final coat of polyurethane.
5. Dry the Finish (Optional)
This step is also optional but usually, people want polyurethane to dry faster to prevent dust nibs from settling on it.
If dust or debris settles on the final coat of polyurethane, it will be difficult to remove it. This is because you can’t sand the last coat. This will make the gel-polyurethane finish blurry and amateurish.
You can use a hairdryer to dry the finish quicker.
Related Read: Can You Apply Shellac Over Polyurethane?
Does Gel Stain Have Polyurethane in It?
Gel stain has a high level of polyurethane chemicals in it. The high amounts of polyurethane in the gel paint is to make the gel stain super durable and water-resistant.
Painters also call gel stain gelled polyurethane due to the high level of polyurethane in it. But gel stain is not polyurethane. Gel stain is softer than polyurethane finish, especially sprayed polyurethane.
Polyurethane is a polymer (or polyol) made from petroleum residue, one reason for its odor. The polyol reacts with isocyanates or diisocyanates to form the thick polyurethane finish. A similar process occurs in gel stains due to the presence of polyurethane (or polyols) in the gel coating.
So polyurethane and gel are very similar but the gel stain is not as good as the polyurethane finish. This is why painters usually advise sealing gel stain with two or three coats of polyurethane.
This is because gel stain doesn’t penetrate the material. Gel stains just sit on the top layer of the material. Since the gel paint doesn’t penetrate, it will bleed through the material if used on high-traffic areas. This will cause the color to also bleed through coats, making the gel finish blurry.
But if the gel stain is sealed with polyurethane, the top layer will be strong enough to withstand heavy use without bleeding through.
Related Read: Can You Apply Polyurethane Over Tacky Stain?
What Kind of Polyurethane Do You Use Over Gel Stain?
The best kind of polyurethane to use over gel stain is oil-based spray polyurethane. Usually, you can use any type of polyurethane to seal gel stain but spray polyurethane sticks better to gel stain. Also, oil-based Polyurethane seals gel stains perfectly.
It’s not advised to put water-based polyurethane over gel stain. This is because water-based polyurethane doesn’t use oil as its solvent. It uses water and water doesn’t stick well to high-gloss finishes like gel.
The water in the water-based polyurethane will not be compatible with the oils in the enamel. If used, the water-based polyurethane will not stick well and it will peel off sooner than expected.
When it comes to sealing high-gloss finishes like gel, the best sealant to use is always an oil-based sealant. This is because glossy stains like gel don’t allow paints to stick properly. This is both due to the gloss and the thick nature of the paint.
So to seal stains like gel, you need a sealant super formulated to stick to glossy finishes. This means oil-based sealants and there is hardly any better than oil-based spray urethane.
Can You Apply Gel Stain Over Polyurethane?
You can apply gel stain over polyurethane. This is because gel stains have a very similar chemical makeup to Polyurethane. Most gel stains contain a large volume of urethane polymers so the gel stain can be used perfectly over polyurethane.
Gel stain is also the best topcoat to put over polyurethane. This is because other topcoats like acrylic enamel will not penetrate the polyurethane coating since the coating is super thick. These topcoats also do not have a similar makeup to polyurethane. So they wouldn’t stick well to polyurethane.
Gel on the other hand doesn’t need to penetrate the polyurethane. This is because gel stains don’t penetrate material as explained before. The gel stain will stick properly to the top of the polyurethane.
Also, gel stain has a similar chemical and paint makeup to polyurethane adhesion wouldn’t be a problem. The gel will also protect the polyurethane.
Tip: For surfaces and materials that will see much action like tabletops and countertops, you can seal with gel and polyurethane. The finish produced will protect the material for years.
Overall, you can use polyurethane over gel stain. This is due to the identical formula of both paints. But you need to prep the gel stain properly before applying polyurethane over it.
The same goes for applying gel stains over polyurethane. Remember not to use water-based polyurethane over gel stain. It wouldn’t work fine.