Poly over Shellac

I am building a built in for a entrance way in my house. It will have
a bench for sitting when putting on shoes, cabinets and coats hooks
on a maple plywood wall over the bench with some figured maple
rails & stiles. I have used some blo with a touch of stain and shellac
to seal. I really like the way it looks right now,but am afriad the
shellac won't be durable enough. The shellac can says not to use
with poly,but I have read that many people do. Whats the scoop ?
Can I poly over it,or should I use varnish ? Any other suggestions ?

Rick,
Welcome to SMC.

If the shellac is dewaxed, then you should be OK, but if not, then you may/will have a problem with adhesion. If you used premixed shellac, and it was not Zinzer Seal Coat, then it was likely a waxed shellac. My impression is that the Sealcoat is the only premixed shellac that is dewaxed.

You can use lacquer (deft is a good choice) over shellac and it will give you pretty good protection.

Welcome John, It's nice to have someone close by on the forum.:D

Rick,

If it was Dewaxed Shellac, you can topcoat with pretty much whatever clearcoat you would like to apply. If it was waxed shellac? The shellac is your finish of choice. I always use dewaxed shellac.:rolleyes: :D

water based poly sticks to non-dewaxed shellac. Oil-based poly doesn't do so well.

IME, shellac is quite a durable finish...and the good thing about it is that ease to repair, unlike polyurethane. If you want more durabilty than shellac while maintaining ease in repairability, I'd go with lacquer. What you want is a finish that 'burns in' with previous coats. This property makes for an easily repaired finish.

Tim, I think you will find that waterborne finishes have even less adhesion to shellac containing wax than oil based poly.

The general rule is not to overcoat wax containing shellac with any waterborne finish or an oil based poly varnish.

I used Zinsser clear premixed. I thought that it was dewaxed.
I read it on their web sight. ( I think). Is varnish a good choice?

Just checked their site agian. Its only their seal that is wax free.

Rick, you can use an alkyd or phenolic varnish over the shellac you used with no problem, or add an application of de-waxed shellac over the existing shellac if you want to use polyurethane varnish for your finish.

As Jim said, you can use a non-poly varnish over the shellac with no problem. While the superior abrasion resistance of a poly varnish will have some benefit in your application, you will lose little if you use a non-poly varnish. Non-poly varnishes are clearer and make a nicer finish too.