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I recently finished a dresser top in a very light gray oil based stain. Afterwards I applied a water based matte poly, because I didn't want any yellow tint to show on the light gray color (see this question).
Should I have used a different combination? So far so good, but am I likely to have problems with poly adhesion in the future because I mismatched the base types of the stain and poly?
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.
Please see this forum thread. To quote from a Minwax representative:
SUBJECT: Minwax Water Based Polyurethane Over Minwax Wood Finish Stains
You may apply the Minwax Water Based Polyurethane over a fully cured Minwax Wood Finish Stain (oil-based). Please use the following guidelines:
To ensure the color fastness of Minwax Wood Finish prior to applying Minwax Water-Based Polyurethane:
- Allow final coat of stain to dry 8-24 hours (Dry time is affected by your ventilation, temperature, and relative humidity).
- Wipe down the stained surface using a soft, lint-free cloth dampened with 100% pure mineral spirits. If the stain is cured and inactive, the mineral spirits will not affect the color. You should not have any color pick-up onto the cloth. The mineral spirits will remove any active/excess stain from surface and help the stain to cure out.
- Allow the mineral spirits to evaporate/flash off the surface.
Once the stain color is set and cured (passed the color-fast test), apply 3 coats of the Minwax Water Based Polyurethane per label directions.
Sincerely, Consumer Affairs
Can I apply water-based polyurethane over an oil based stain?
Short answer: yes.
Longer answer: if you wait for the oil-based stain to properly 'dry' (cure) it's no longer oily. This is because the curing process for oil is polymerisation, and polymerised oil is akin to resin.
So far so good, but am I likely to have problems with poly adhesion in the future because I mismatched the base types of the stain and poly?
Obviously the time between stain and varnish application will be a factor. But if you didn't experience major problems with beading of the waterbased poly as you were applying it I think you're OK.
If you want to take an extra precaution you can use shellac as an intermediate coat. This can also be used to speed up the process because the shellac can go directly onto oiled wood without waiting for the oil to dry. Then you can overcoat the shellac with your final finish after just waiting for the shellac to dry enough, perhaps as little as an hour.
Even with "super-blonde" shellac there's some yellow colour of course, but it's applied very thinly so the effect should be minimal.
