Why shellac under poly/varnish

Jon, you could do just that without any problem. One use of shellac that I would recommend is on stained wood. A seal coat of shellac will prevent the stain from “bleeding” into your topcoat of poly/varnish.

I prefer to use it as a base coat simply because I like the finish that I get after topcoating with poly/varnish, especially with open grain woods such as oak. But this is largely a personal choice and you could just as easily get by with building a poly/varnish finish without using shellac.

-- With God's help all things are possible- even woodworking. Woodworking is not just a hobby, it is an (expletive deleted) expensive hobby.

I totally agree with Scott. I use it because it is so easy and fast to apply. You can get 3 coats of shellac on in less than two hours and you will find it takes a lot less top coats to get the desired finish. It just builds up and seals nicely.
I would also add to what Scott said is that shellac is the universal under/overcoat. It can go over or under any stain, oil, or water based finish. This lets you mix and match your finishes to get where you want.

-- Rich in Richmond

If the finish is only wiping varnish, the shellac is not necessary for protection or color purposes.

On some woods, the shellac may seal the wood better than early coats of wiping varnish, changing the surface texture. In those cases, most any sanding sealer would provide the same benefits.

Grab a decent sized piece of scrap left over from your project. Cut a shallow kerf down the middle, sand, and otherwise prepare it for a finish. Coat 1/2 with shellac. Once the shellac dries, do the entire board with several coats of wiping varnish. Do one additional coat of wiping varnish on the side without the shellac to make up for the extra layer.

If you want to do lots of sanding, dedicated sanding sealers are easier to sand than shellac. The dedicated sealers won’t “pill” on the paper.

-- - Please help keep Lumberjocks an enjoyable escape by refusing to participate in political discussions. Simply spit out the bait and ignore the thread...

Another point- Shellac gives more, and faster depth to a finish.

I usually do 2-4 coats of shellac, then then 2 coats of lacquer or high gloss varnish. Then steel wool, wet sand to 800, then pumice, then wax.

-- The only easy wood project is a fire

I often use Shellac for its coloring, it gives the wood a deep, rich tone. This is important if you are using a water based poly, which tends to have a washed out appearance. Water based finishes definitely have their place in the shop but they import no depth or tone nor do they bring out the grain and figure of the wood. Shellac can do all of these and is fast drying. I will probably use just shellac on the side table I am build. One big reason, it is also easily repairable. Around my house, that is very important. If I need to go back and be able to repair a piece shellac is the easiest to repair.

-- Greg - Charles Town, WV

Thanks so much everyone. That’s exactly what I was looking for.

-- Jon

Some one mentioned that you can put anything over shellac. Thats true if you have de-waxed shellac. The wax can cause problems with other finishes. the Zinsser sanding sealer is a de-waxed shellac as is the spray cans of shellac. If you want to use an orange shellac to give the project some color tone then you can cover it over with the sanding sealer and you are then ready to go with any kind of topcoat that you want.

This info cames to me from Gene Hoyas who is the product manager from Zinsser. Gene used to come to the East Coast Woodwoking shows. I’d walk in with an empty Zinsser Shellac can and ask him to fill it up. He’d always give me a new full can. A great guy to talk to.

-- What happens in the workshop stays in the workshop. No wait that doesn't sound right. Karson Southern Delaware karson_morrison@bigfoot.com †

I like to use as stated above and when makeing roepairs. It can up blend a new peice of wood with older wood.

The rapid build and initial sealing qualities would be of benefit if there was no other special needs that dewaxed shellac offers.

Before I had spray equipment I used the wipe-on poly because it was easy, each coat dried (relatively) quickly, and it was hard to screw up. I never used shellac as the base coat and all my work turned out fine.

I would back the comments of every other LJ and their experience on the matter.

-- Todd A. Clippinger, Montana, http://amcraftsman.com