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While stain and polyurethane are products commonly used to enhance and protect wooden surfaces, both products come in “water-based” and “oil-based” variants. Since oil and water are immiscible that don’t mix uniformly, many people have questioned whether water-based polyurethane can be used over oil-based stains.
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Can You Apply Water-Based Polyurethane Over Oil-Based Stains?
While water and oil may not mix well, you can apply a water-based polyurethane coat over wood treated with an oil-based stain. The oil-based stain is designed to penetrate the wooden surface and alter the color as porous gaps in the wood are filled with stain – which is why the oil-based stain must be applied first!
The water-based polyurethane can then be applied once the oil stain has cured.
Adhesion problems are common when oil-based stains haven’t properly dried and cured before the clear polyurethane coat is applied.
When the correct steps are followed, the water-based polyurethane will fix minor cracks and flaws on the stained surface.
As a golden rule, any type of polyurethane can be used over oil-based stains, provided the stained surface has dried and cured.
Due to this, the most important part of using water-based polyurethane over stained wood is waiting for the stain to dry.
There are benefits to using a water-based polyurethane instead of an oil-based variant.
Ultimately, water-based polyurethane coats are clearer than oil-based variants after drying. Due to this, using a water-based variant is preferable when an oil-based stain has been used. Using an oil-based polyurethane over an oil-based stain can affect the final color of your stained wooden surface, making it darker than the original color of the stain.
Can Water-Based Polyurethane Be Mixed With Oil-Based Stains?
Even though water-based polyurethane can be used over oil-based stains, you cannot mix these two products because the oil and water will not mix properly.
If you want to mix a stain with polyurethane, you must combine an oil-based stain with an oil-based polyurethane or a water-based stain with a water-based polyurethane.
There are also pre-mixed stain and polyurethane products available today, including Minxwax’s PolyShades Wood Stain and Polyurethane, which is available in two finishes (gloss or satin) and fourteen color options.
The coats must be applied separately if you’re using an oil-based stain with water-based polyurethane.
How to Apply Water-Based Polyurethane Over an Oil-Based Stain
Follow these steps to apply a water-based polyurethane product over an oil-based stain product!
Step One: Purchase the Needed Supplies
You will need to purchase the following tools and supplies to apply a water-based polyurethane over wood that’s been stained with an oil-based staining product:
- Oil-Based Wood Stain (30 stain colors to choose from)
- Water-Based Polyurethane
- 120-Grit Sandpaper
- 400-Grit Sandpaper
- Dust Mask
- Tack Cloths
- Paintbrush
Step Two: Sand and Clean the Wooden Surface
Start by sanding the surface you want to stain with 120-grit sandpaper to ensure no streaks or bumps can affect the final appearance. Always sand the surface in the direction of the wood grain for the best results.
Make sure to clean the wood after sanding it. You can skip to Step Four if the surface has already been stained with an oil-based stain!
Step Three: Apply the Oil-Based Stain
A synthetic brush can now be used to apply your chosen oil-based stain to the wood. Always apply the stain against the wood grain’s direction to ensure the stain absorbs into the wood.
Use a tack cloth to wipe any excess stain away after thirty minutes. Ensure each stain coat dries for two hours before an additional coat is applied.
Step Four: Sand Down the Stain Coats
Once each coat has dried properly, you’re ready to sand down the stain coats. Use 400-grit sandpaper and work in the grain’s direction.
This step is essential and will ensure that the water-based polyurethane adheres to the stained wood without any unwanted layer separation. Make sure to clean the surface again after sanding.
Step Five: Apply the Water-Based Polyurethane
You can apply your water-based polyurethane after sanding and cleaning the stained wood. Use a clean synthetic paintbrush to apply thin coats of polyurethane in the direction of the wood grain.
It’s important to apply even pressure to prevent blotches and streaks on the surface. Overbrushing your stained wood can negatively impact the final product’s appearance.
Step Six: Sand Down the Polyurethane Coats
The polyurethane coats must completely dry before you can sand them down. Luckily, water-based coatings dry faster than oil-based polyurethane coats!
Use the 400-grit sandpaper to gently sand the polyurethane-coated surface in the direction of the grain. More than one water-based polyurethane coat can be applied to the stained wooden surface.
Frequently Asked Questions
Can Water-Based Polyurethane Be Stained Over With Oil-Based Stains?
Homeowners can use oil-based stains to safely stain over wood with water-based polyurethane that’s been previously treated. You can also use a staining product that’s formulated to be used over polyurethane-coated wood. Always test the oil-based stain over a small part of the polyurethane-coated surface before staining the wood.
How Long Must Oil-Based Stains Dry Before Water-Based Polyurethane Is Applied?
Your stained wood must be completely dry before you apply the water-based polyurethane. You can detract from the final appearance when the polyurethane is applied before the stain has dried. Wait at least 72 hours (three days) for the oil-based stain to dry and cure. You can then apply the polyurethane to the stained wood.
Will Water-Based Polyurethane Change the Color of Stained Wood?
Unlike oil-based polyurethane, which slightly alters the color of stained wood, using water-based polyurethane will not affect the color of the stained wood when done correctly. Following the tips in this YouTube video will ensure your oil-based wood stain shines through the water-based polyurethane coating!
Conclusion
You can use a water-based polyurethane over wood stained with an oil-based staining product. The oil-based stain will penetrate the wood to alter its color, and the clear polyurethane coat will protect the wooden surface. Unless you’re using a pre-mixed polyurethane stain, the oil-based stain must be dry before the water-based polyurethane is applied.
