As a professional or a DIYer, you may have used polyurethane once or twice in your projects. Polyurethane offers plenty of benefits, including water and moisture protection plus durability.
However, as time goes by, polyurethane may chip off, which may need restoring. In this article, I’ll address a common question many of us have faced: can you stain over polyurethane? Let’s dive in!
Is it Possible to Stain Polyurethane-Coated Surfaces?
It is possible to stain surfaces with a polyurethane coating. However, you can stain the wooden surface using only gel stain. Once you apply gel stain, it can result in a film on the polyurethane finish.
It is different from standard wood stains, as it penetrates deep into its wood pores.
Factors to Consider When Staining Over Polyurethane
Planning is paramount for any project. As I delve into choosing the best stain over polyurethane, here are some critical factors you should consider if you’re thinking about staining:
Ensure Wood is in Good Condition
The first factor to consider when you apply stain over polyurethane is the wood you will be using. It should be in good condition. Make sure that the wood does not have any watermarks, deep scratches, and missing veneers.
It would be difficult to apply gel stain along the wood grain if the wood is badly damaged. Therefore, applying gel stain on wood in bad condition is not a good idea. If you are working on a bad piece of wood, you may need to fix it first.
Apply the Right Amount of Stain
Make sure to apply the right amount of wood stain on the polyurethane surface of the wood. Very thick coats of gel stain can lead to a longer drying time. A wood stain can dry between hours to several days until the stained wood cures.
Additionally, thick layers of gel stain can result in patchy colors. For the best results, apply thin coats. In my experience, I’ll layer more thin coats until I achieve the desired shade.
Don’t Use a Power Sander
Another factor to consider is the type of sander. Do not use a power sander or coarse sandpaper to avoid getting traces or scratches on the surface. All you need to do at this point is to scruff the wooden surface to allow the gel stain to adhere properly.
Do not sand down the whole surface or the entire top coat to bare wood. A power sander might do just this. A power sander is difficult to control, especially when applying certain pressures, and might sand the surface to the bare wood.
Opt for a Darker Finish
Before you apply wood stain, plan this process properly by identifying the shade of the wood stain you would like to use. It is best to use a darker tone of the shade of stain to hide imperfections on the piece of wood you are working on.
Refrain from using a lighter stain. Make sure to use a darker stain of gel stain compared to the original color if you plan to stain over a wooden surface covered with polyurethane.
Different Types of Wood Stains
Different types of wood stains are formulated for various tasks. It is important to know each and every one to help you decide which one best serves the purpose of the wood project.
Gel Stain
A gel stain has a thicker consistency compared to other types of products that can stain wood. Thus, it can be applied at a vertical angle since it will not drip.
It is generally an oil-based gel stain it also has a darker hint. Thus, it can deepen the shade of the surface.
Water-Soluble Dye Stain
A water-soluble dye stain comes in powder form. You need to add some water to make a paste before you can use it. This is a highly versatile wood stain that comes in different colors. However, it is sensitive to ultraviolet rays which fade color as time passes.
Oil Wood Stain
Oil-based wood stain is one of the most common options and the first stain type to be formulated for woodworking use. A good oil-based wood stain is best for hydrating wooden products.
This can be in the form of linseed oil or flax oil which are sourced from the flax plant. It is a wood stain that comes from natural oil.
Water-Based Stain
Water-based stains are more environmentally friendly since their formulation does not include chemicals. This wood stain has a longer life span without compromising the strength of the wooden surface. They dry faster compared to other stains.
Shellac, Varnish, and Lacquer
If you wish to layer on your wooden project, shellac, varnish, and lacquer are other options. These products are occasionally formulated to have pigment which can stain the surface.
They are also excellent sealers that protect the surface. Furthermore, you can stain over varnish and lacquer.
How to Apply Gel Stain on Polyurethane
Now that you know that you can stain over polyurethane, make sure to use gel stains. Gel is formulated to have urethane [1], the same component that can also be found in polyurethane.
Since they both have similar formulations, applying gel stain on polyurethane is not a problem. It will bond to the polyurethane surface. The process is easy. Follow these steps to know more.
Tools and Supplies Needed
- One can of gel stain
- Disposable gloves
- Foam applicator
- Lint-free cloth
- Dropcloth or plastic sheeting
- Fine grit sandpaper
- Tack cloth or microfiber cloth
- Orbital sander
Step 1: Dissemble and Prepare the Wood Pieces
Before anything else, disassemble any hardware on the furniture and get the wooden pieces ready. This includes removing handles or knobs.
Step 2: Clean the Surface from Grime, Dirt, Etc.
Proceed to remove and clean the surface of grime, grease, and dirt. The presence of these will compromise the quality of the wood stain on top of the polyurethane finish.
You can clean the surface using a solution of water and denatured alcohol. Using a scouring pad, add some cleaning solution to it and slowly wipe the surface to remove any dust. You can also use a solution of warm water and some liquid detergent.
Krud Kutter is a powerful degreasing item. It is sprayed on the surface using a clean rag to remove dirt and oil. Using a cleaner will require a wet cloth dampened into clean water.
This application of clean water is important. It effectively removes traces of the product from the surface before staining it. Once you have cleaned the surface, allow it to dry for about an hour or more.
Step 3: Sand the Wood Surface and Clean the Dust
Begin by lightly scuff-sanding the wood surface with fine-grain sandpaper. This step helps soften and smooth out the surface, removing any minor flaws or scratches. It’s crucial not to skip this light sanding if you want a seamlessly smooth finish.
A 320-grit sandpaper can do the job of sanding the surface lightly on your wood projects. The light sanding will also result in a de-gloss-like surface which would allow the gel stain to adhere better.
You can also opt to use a sanding sponge. It is flexible and will definitely perform excellently without leaving behind any sanding marks. When light sanding the surface, make sure to sand along the direction of the wood grain.
Once you have lightly sanded the surface, clean the resulting sanding dust and other residual material using a damp rag. Cleaning the surface will remove any residue. This will make the surface even once the gel stain is applied.
Step 4: Apply the Gel Stain
Use a foam brush to apply the gel stain once the surface is prepped and ready for application.
Stain over polyurethane-coated surfaces evenly across the wood surface. Make sure to cover every inch of the surface with a liberal amount of gel stain.
Step 5: Wipe the Excess Stain and Wait Until Dry
Wipe off and remove the excess gel stain found on the surface using a tack cloth. While wiping the gel stain off, you can also distribute the stain into an even and thin layer. Wiping the extra stain off is important. It will affect the final finish on the surface.
If you want optimal results, rub the stain in a circular motion. Make sure to wipe the grain in a back-and-forth motion as well. These applications will ensure that the stain is evenly distributed across the surface.
You can initially start by lightly wiping the surface and then gradually adding pressure if necessary. If you want a darker shade of wood color, allow the coat to dry completely, then add another coat.
You may apply as many coats of gel stain as possible until you have achieved the color that you want.
Once you have applied the desired number of coats and have achieved the color of the surface, it is time to allow it to dry completely. The drying times of gel stains are different depending on the weather.
Step 5: Seal the Stain/Apply Protection
Once the staining is done, it’s crucial to seal it for added protection. Gel stains, while effective, aren’t inherently long-lasting. Therefore, a supplementary product is needed; choose a final product that’s colorless to preserve the original wood stain.
A clear topcoat is the ideal finish to protect the stain over the polyurethane layer. There’s a variety of clear coats on the market, and selecting the right one can make a significant difference in the outcome:
1. Polyurethane
It would be wise to use an oil-based polyurethane as a topcoat since gel stain options have urethane.
2. Lacquer
Lacquer is formulated to consist of shellac together with synthetic materials or alcohol. It will adhere to a layer of gel stain. Once the lacquer has dried down, it forms a protective coating to retain the wood stain color.
3. Shellac
Shellac results in a hard coat once it has dried down completely. It keeps the stained wood protected from peeling and stripping off.
It is best to apply a product using a spray gun. This is an easier way of application and does not rub an object on the stained surface. Spraying the coat also results in better coverage on the whole surface.
Step 6: Reassemble the Wood Pieces
Reassemble the wood pieces, hardware, and metal attachments once you are done with the staining process.
How to Apply Poly and Stain in One (Minwax PolyShades)
In addition to gel stain alternatives, one option to consider for covering polyurethane is a fusion of wood stain and polyurethane.
Minwax PolyShades stands out in this category. It’s recognized as one of the leading oil-based stains, which reduces the overall finishing time. It’s also user-friendly, consistently yielding impressive results.
Step 1: Clean and Prepare the Wood Surface
Clean and prepare the wood surface by degreasing it. Choose your preferred degreasing agent, especially if there is visible grease on the surface. Allow the surface to dry after cleaning it.
Once the surface is clean and dry, proceed to lightly sand it with a fine grit sandpaper such as 320-grain sandpaper. Once you have sanded the surface, proceed to wipe it clean with a clean and damp cloth to remove the residual dust.
Step 2: Coat the Wood with PolyShades
You can directly coat the wood with PolyShades once you have completely cleaned and sanded the surface. You will no longer need to use any wood conditioning procedures before staining it.
Make sure to mix the PolyShades thoroughly with a mixing stick. Once you have mixed it thoroughly, apply the PolyShades on a piece of scrap wood to see how it would look. This will give you an idea of the resulting color once applied to your project.
If you are happy with the resulting color, you can now apply a thin layer of the PolyShades in the same direction as the wood grain. Make sure to apply an even coat that would cover the entire surface of your project.
Step 3: Clean the Brush
After staining the surface, do not forget to clean the brush. Mineral spirits can easily clean the brushes. Soak and swirl the brushes in a bottle of mineral spirits for approximately two minutes.
Shake the brushes to remove the excess mineral spirits and denatured alcohol. Pat the brushes on a clean rag to dry.
Step 4: Let the Stain Dry and Recoat as Needed
Let the stain dry completely before applying polyurethane, which is approximately six hours. If you would like to have a darker shade, then you can recoat the surface as needed. Before applying additional coats lightly scrub the surface with a fine steel wool.
You can add up to two coats of stain depending on the shade of color you prefer. Allow the coats to dry up completely before applying another coat of gel stain mix.
More Guide and Tips Here:
Extra Tips for Staining Over a Poly Finish
Now that you’re equipped to stain over polyurethane, here are some additional tips I swear by to ensure a smooth and flawless finish:
- When brushing on the stain, always go with the direction of the wood grain. This helps ensure a more natural and cohesive look.
- Think about the final tint you’re aiming for. Opting for a darker hue often results in a richer finish, while lighter shades might not provide the same depth or coverage.
- Make sure to consider the adherence of the wood stain. Use a combination of a gel stain or stain and polyurethane that can easily adhere to the finish without any problem.
FAQ
Can you put gel stain over old stain?
You can apply gel stain over old stain. Since gel stains are pigmented and only sit on the surface rather than penetrating the wood grain, they can be used to cover up stained wood.
However, there are a few considerations to keep in mind. It is crucial to ensure that the old stain is thoroughly cleaned and free of any dirt, grime, or wax buildup before applying the gel stain.
Is the quality of gel stain the same as regular stain?
The quality of the gel stain is the same as a regular wood stain. One main difference is that gel stain options are formulated to sit on the surface, whereas regular wood stains are formulated to penetrate the wood.
Can you stain over water-based poly?
You can stain over water-based polyurethane. It is best to apply gel stain over water-based polyurethane. The gel stain would also need to be water-based in the formulation. Scuff the surface to allow the stain to adhere to the surface properly.
Can you use an oil-based stain over poly?
You cannot use an oil-based stain over polyurethane. The stain can easily be removed and will leave no color. Oil-based stain works by penetrating into the wood stoma. However, polyurethane will not allow the stain to penetrate through.
How long should you leave the gel stain to dry over poly?
You should leave the gel stain over polyurethane for approximately 8 to 24 hours. However, if you have applied more than one coat, you should allow the gel stain to dry for approximately 8 to 24 hours between coats.
Should you sand in between coats of stain and poly?
You should sand in between coats of stain and polyurethane. This practice will help eliminate imperfections such as scratches and dents that might appear after the process.
Will stain penetrate polyurethane?
The stain will not penetrate polyurethane. Polyurethane, once completely dry, will result in a hard coat that is impenetrable.
Can you apply poly over the stain?
You can apply polyurethane over the stain. Make sure to sand the surface before applying the stain to allow it to adhere more to the surface.
How do you fix a mistake when applying gel stain?
You can fix a mistake when applying gel stain by gradually adding varnish to the mix and applying additional coats to the surface until the mistake, blotch, or the existing stain has been fixed.
You can also add paint thinner to the mix. Another fix is to use a dark shade that can hide mistakes on the surface.
Conclusion
If you are pressed for time, and you need to change the stain of your furniture, or you need to restore one, then do not worry. You can easily apply a stain over polyurethane, which will make the piece look new.
Make sure to have all the materials, such as a spray gun ready. I hope this article has shown how you can stain over polyurethane and more!
You've probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.
Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
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