OIL/Water Clear finish

[Larry Crim]

Just a question can I apply water based clear coat over oil based clear? both GF clear
Thanks
Larry

[Prashun Patel]

In general, no.

If you can't stay with oil, then you should put a sealing coat of dewaxed shellac on the oil. Then the water top will adhere.

[Howard Acheson]

Why do you want to do this? Waterborne is a lesser durable finish than the oil based.

In general, if the oil based undercoat if completely dry, all you need to do is to scuff sand the undercoat with 320 paper and you can apply an waterborne finish with no problem. However, to be safe, allow the oil based finish to cure for 3-4 weeks

[Jason Roehl]

Howard, that's not necessarily true. Today's waterbornes are incredibly durable (and getting better all the time). Prep, method of application and film thickness are important performance factors that are often overlooked. Not to mention, much more R&D is being put into waterborne coatings as more and more locales ban the sale of oil/alkyd-based products in any significant quantity.

[Howard Acheson]

I agree waterbornes have improved but I do not know of one that can stand up to damp conditions or to many household cleaners. Nor do I know of any that work well in a marine environment. An oil based finish is generally impervious to almost any moisture or household cleaner.

[Jason Roehl]

CHEAP waterborne polys don't hold up well. Part of this is because the cheap ones are incredibly thin, so even 4-6 coats doesn't build much of a protective film. WB floor finishes are especially tough. The problem I see with oil/alkyd-based products is that they get too hard (save for spar varnishes), then as wood moves, they crack and craze, which allows moisture penetration. The WB finishes stay more flexible much longer. A marine environment is a whole 'nother ballgame, but I can say that the exterior WB polys I've used on stained fiberglass entry doors has held up much better than expected, even after 4-5 years (2 years is generally considered the max for anything without pigment in an exterior application).

[Larry Crim]

via previous post I used oil based clear on the interior of a cherry chest that has some cedar lining. The clear on the under side of the lid went tacky and I have removed it and am refinishing it now with water base clear the issue is there are some areas inside the chest not covered by cedar that did not get tacky and would be very hard for me to strip assembled, thinking if they were not tacky I might be able to just scuff then apply a few coats of water base clear to ensure it does not happen in the future.
Thanks
Larry

[Jamie Buxton]

I've finished some projects with an initial coat of wipe-on solvent-based varnish, followed by several coats of spray-on waterborne. It worked just fine, as long as you wait for the solvent-based varnish to cure properly.