Reply To: Varnish on bare wood?
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I think your instinct for shellac is sound unless there will be lots of alcohol around, like a bar top.
Shellac was a standard prep in a boatyard I worked in. It is a better vapor barrier than poly, is harder, and will assure a better bond to the wood. You can also get several coats in a day and sand between coats. Fixing mistakes is also easier.
Some poly won’t stick well to itself once dry, so sanding is a must and the time between coats is longer.
Most poly is tough, but not hard. There are exceptions. Behlen Rock hard and Pratt and Lambert #38 are a couple. Price them out and shellac will sound a lot more attractive for multiple undercoats.
One caution. I’ve always used waxed or I waxed shellac under spar varnish. That works fine, but I believe poly requires unwaxed shellac ( Sealcoat)
And Ive found recoating dried poly doesn’t work well unless you sand first to give the new coat “bite”. If you miss spots, it can delaminate.