I have put 2 coats of coating epoxy onto marine ply.

Then I applied one coat of Epifanes varnish 48 hours ago. The varnish is not drying.

Is there an incompatibility?

Should I wash the epoxy coating, as I have read elsewhere?

One professional adds cobalt drier to the varnish to fix the problem. Do you know about this?

I have only used a test piece of plywood so far. Also a narrow strip of pine (same problem).

Thanks

You would need to check with the manufacturer of the varnish for epoxy compatibility.

Generally all you need to do is give the epoxy a light key with sandpaper then a clean to remove any dirt/dust or greases and it will be fine for painting or varnishing.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

how long between putting down the epoxy and varnishing?

Thanks for the replies.

I varnished 24 hours after the second coat of epoxy. I rubbed down and wiped with acetone.

Here is the reply from Epifanes:

We typically recommend waiting 10 days (It takes that long for epoxy to cure and for the production of blush to stop). Depends on drying conditions of course. Once sanded, the epoxy should be washed with acetone, ammonia, or vinegar. Finally, a warm soapy water wash.

When asked about waiting longer, here is their other reply (I mentioned using Cobtalt drier):

It might still dry. There is cobalt drier in varnish currently. Adding more will produce a less flexible (won't last as long)  finish.Honestly, remove the varnish (likely it will come off with solvent) clean off the blush and recoat.

So I've decided to wait 10 days and do what they say. Rather a lengthy process but the Epifanes finish is great. I wish I had removed the bubbles using a hot air gun though. I suppose I can rub them down. I'm only making a toilet enclosure, so the finish isn't crucial.