Hello, I'm an expert in home improvement and DIY projects with a focus on wood finishing. When it comes to applying a water-based polyurethane over an oil-based stain, there are a few considerations to keep in mind.

Firstly, it's important to ensure that the oil-based stain is completely dry before you apply the water-based polyurethane. Oil-based stains can take a long time to dry, sometimes up to several days, depending on the specific product and environmental conditions. If the stain is not fully cured, it can prevent the polyurethane from adhering properly.

Secondly, you should lightly sand the surface with a fine-grit sandpaper (around 220-grit) after the stain is dry. This will help to create a smooth surface for the polyurethane to adhere to and will also help to remove any potential contaminants that might interfere with the bond between the stain and the polyurethane.

Thirdly, always follow the manufacturer's instructions for both the stain and the polyurethane. Some products may have specific recommendations or warnings about being used over other types of finishes.

Lastly, it's a good idea to test the compatibility of the two products in an inconspicuous area before applying them to the entire surface. This will help you to ensure that there are no adverse reactions between the stain and the polyurethane.

In summary, while it is possible to apply a water-based polyurethane over an oil-based stain, it requires careful preparation and adherence to the drying and application instructions to ensure a good result.

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This should be ok if you gave the stain 3-4 days to properly dry out. You'll want the oil-based drying agent to completely vaporize from the stain before applying the water-based finish. You may apply the Minwax Water Based Polyurethane over a fully cured Minwax Wood Finish Stain (oil-based).read more >>