Varnish Questions

[ScottyAdams]

Hey guys,

We have a question about some varnish. We've been varnishing some wood with an oil based varnish. We ran out last night, the sign is due tomorrow. there were imperfections on the finish. We sanded the wood down a bit (not completely removing oil varnish but smoothing out). We only had a water based varnish in house. We applied a thin coat of the water based varnish on top. Our boss is saying it won't work and will chip and peel off in a month's time. it looks awesome right now but I dont want to deliver a sign that will chip and crack in such a short time. Does anyone else have experience like this? Thanks!

 

[Gino]

That's a good question.

Usually when having the oil based product on first... the top clear can be water based, but it depends on many factors. Oil based will breathe at a completely different rate than the water, so if you have enough layers, like maybe 6 or 8 coats, it might work. Otherwise, as the harder clear expands and contracts.... the other is going to do it at a much faster speed and this is what will create the blistering or spider-webbing/crackling.

Is this going to be interior or exterior ??
Will it face south or a lot of sun ??
Will it be under four seasons of weather ??
What is under the clearcoat ?? In other words what are you clearing overtop ?? Hand painted graphics/words or vinyl ??

 

[John Butto]

The safe rule is if you start with an oil base you finish with oil base, listen to your boss.

 

[skyhigh]

when you say you sanded it down, but didn't completely remove the oil......I'm thinking you took it down pretty much? If you did, and the finish was dull, then you may be good.

I agree with keeping with what you started with to be on the safe side. Being at the stage you are, I would leave it. I really do think you may be ok.

At worst, you have to redo (but why jump the gun).....at best it looks awesome, and hopefully will remain that way.