Shellac questions...

Re: Shellac questions...

Sam Simpson

>Hi Y'all,

Actually Steve, not such a basic question.

The thinner the mix, the crisper the shellac will dry. This is an advantage or disadvantage, depending on how you are applying the shellac, and at what point of the finish build process you are.

A very thick soup of shellac will take a very long time to dry, and will have a gummy texture even after a long time. A very thin mix will dry very fast but leave little on the surface to be of much use in building a finish.

It is therefore a common practice to start the bodying up process using a thick mixture (3lb) and reduce the mixture each application, until by the end of the process you are applying almost pure spirit.

One short cut French polishing method would be to brush on a coat of 3lb then sand lightly. Thin the mix and recoat. Do this three or four times until you have a foundation. Wet sand smooth, then with 1lb cut or less start to apply the finish by wiping it on. Add a little oil to the rag and create a thin smear of oil on the work surface, so that subsequent thin coats of shellac are passed through the oil film and deposited on the surface.

The trick here is to have the rag about as damp as a spent tea-bag and to apply the shellac in more of a buffing routine than a wiping on of wet liquid.

Regards Sam Simpson.

Re: Shellac questions...

Alan Hamilton

>Steve, sam

Yes. Adding a quantity of alcohol that's equal to the volumn in the can will halve the cut. As you know, a "cut" is determined by the weight of shellac dissolved in a gallon of alcohol--or the equivalent in whatever measure is used. A three pound cut is simply three pounds of shellac dissolved in one gallon of alcohol. So if you add another gallon of alcohol, you'll have three pounds of shellac dissolved in two gallons of alcohol, or a pound and a half for each gallon: i.e., a 1 1/2 pound cut.

I have to disagree with Sam. Even coats is the aim, and a thin shellac, like a 1 or 2 pound cut, is easier to apply than a heavier cut. A thin shellac will also penetrate better, which makes for a much better under-coat for any finish that follows. On splotch-prone woods, like pine or cherry, a "wash coat" of shellac, a 1 or 2 pound cut, is regularly used as a sealer under stains and varnishes to prevent such problems.

In my own work I always mix up about a 1 1/2 pound cut and I use it for all purposes. It's thin enough to be a very good wash coat, and if I'm using it as the finish, it's thick enough to build fairly fast. I've not seen the need to use a heavier coat, and the lighter coat avoids problems that can arise using a heavier coat, such as too much build at the edges, runs, and so on.

Jeff Jewitt recommends using a 2 pound cut for a wash coat, and I believe also for build coats; and IIRC Jewitt recommends a 1 pound cut for French polish. It's been awhile since I read his book, but I don't remember him using anything more than a 2 pound cut. As above, I don't see a reason to risk the troubles that a heavier coat can cause, when a thinner coat is easier to apply and builds quickly enough.

I love shellac. Probably my favorite finish is garnet shellac with wax over it, buffed to a glow. It's gorgeous on pine, oak and walnut.