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Oil-based polyurethane and water-based stains are two products that are widely used to enhance and protect wooden surfaces. Since water and oil are immiscible liquids that don’t mix uniformly due to their differing properties, many homeowners have questioned whether oil-based polyurethane can be used over a water-based stain.
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Can Oil-Based Polyurethane Be Applied Over Water-Based Stains?
While oil and water are immiscible, an oil-based polyurethane clear coat can be applied over wood stained with a water-based product. The water-based stain will penetrate the wood fibers, allowing the color to penetrate the wood as porous spaces are filled in the wood. Due to this, the water-based stain must be applied first for the best staining results.
Oil-based polyurethane can then be applied to the surface of the stained wood once the water-based stain has dried and cured.
Unlike stains, oil-based polyurethane doesn’t penetrate deeply into the wood but forms a protective layer over the surface of the stained wood.
The oil-based polyurethane will fill minor cracks and imperfections on the surface of the wood.
The wood stain can be used to highlight the wood grain and enhance the surface’s appearance, while the polyurethane will protect the wood against scratches and dents.
Polyurethane also adds waterproofing properties to the wood, which can help wooden surfaces withstand different weather elements.
Can You Mix Oil-Based Polyurethane With Water-Based Stains?
While oil-based polyurethane can be applied over water-based stains, you will not be able to mix these two products since oil and water do not mix well. If you want to mix polyurethane and stain, you’ll need to use a water-based stain with a water-based polyurethane or an oil-based stain with an oil-based polyurethane.
If you’re using an oil-based polyurethane with a water-based stain, you will need to apply the coatings one at a time.
Only apply the oil-based polyurethane coatings after the water-based stain has properly dried on the wooden surface.
We’ll outline the correct steps to use these two products in the following section!
How to Apply Oil-Based Polyurethane Over a Water-Based Stain
Follow these six simple steps to use an oil-based polyurethane coating over a water-based stain!
Step One: Gather the Necessary Supplies
You’ll need the following materials and tools when applying oil-based polyurethane over wood that’s been stained with a water-based product:
- 120-Grit Sandpaper
- 400-Grit Sandpaper
- Water-Based Wood Stain
- Oil-Based Polyurethane
- Dust Mask
- Tack Cloths
- Paintbrush
Step Two: Sand and Clean the Surface
Use 120-grit sandpaper to smoothen the surface of the wood. Doing this will ensure there aren’t any bumps or streaks on the surface that detracts from the wood’s appearance.
Make sure you sand in the direction of the wood grain! Proceed to Step Four if the surface you want to apply polyurethane to has already been stained.
Step Three: Apply the Water-Based Stain
You can now use a brush to apply your chosen water-based stain. Make sure to apply the stain in the direction of the wood grain to ensure the stain absorbs properly.
Once the stain coat has settled for thirty minutes, use a tack cloth to wipe away any excess stain. The first coat must dry for two hours before the second coat is applied.
Step Four: Sand Stain Coats Once Dry
Once all of your stain coats have dried for eight hours, use your 400-grit sandpaper to sand the stain coats.
Once again, work in the direction of the wood grain. Sanding the stained wood will ensure the oil-based polyurethane is properly applied to the stained surface without any layer separation.
Clean the wooden surface again when you’re done sanding it down.
Step Five: Apply the Oil-Based Polyurethane
You can start applying the oil-based polyonce the water-based stain has fully dried and been sanded.
Use a clean paintbrush to apply the polyurethane coating in the direction of the wood’s grain.
Make sure to use even pressure and apply thin coats to prevent any unwanted blotches and streaks.
Avoid over-brushing since it can damage the wood’s appearance.
Step Six: Sand Polyurethane Coats Once Dry
You must wait for it to dry before you can sand the polyurethane fully. Oil-based polyurethane will take longer to dry than water-based variants.
Polyurethane will be done curing within three days. You can use 400-grit sandpaper to gently sand the wooden surface.
You can apply more than one polyurethane coat if desired.
Frequently Asked Questions
Can Oil-Based Polyurethane Be Stained Over With Water-Based Stains?
You can use a water-based stain over an oil-based polyurethane coating when the correct steps are followed. It’s important to test the stain over a small part of the polyurethane before proceeding to stain the wooden surface. You can then use a brush or rag to stain the polyurethane-coated surface. There are also
stains formulated to be applied over polyurethane.
How Long Must Water-Based Stains Dry Before Applying Oil-Based Polyurethane?
It’s important to let your stained wood fully dry before a polyurethane coating is applied. As a golden rule, the water-based stain must cure for three days (72 hours) before the oil-based polyurethane is applied. Applying the oil-based polyurethane before the water-based stain has dried will yield poor results that negatively affect the wood’s appearance.
Will Oil-Based Polyurethane Change the Color of Stained Wood?
Applying an oil-based polyurethane coating to wood stained with a water-based stain will slightly alter the color of the wood and make the stain color darker and richer. The difference will not be too noticeable but will highlight the natural beauty of the wood. Choosing a lighter stain color can mitigate these effects. Here are some more tips for choosing a stain color!
Conclusion
You can apply an oil-based polyurethane coating over wood that’s been stained with a water-based product. Since the water-based stain penetrates the wood, it must be applied before the clear polyurethane coating protects the wooden surface. The water-based stain must be completely dry before the protective polyurethane is applied for the best results.
