On 6 Dec 2004 at 22:02, Jonathan Peck wrote:

> So can anyone explain the mixing of shellac and the cuts/ratios in
> real simple terms? Do I start with a thin cut and rub on, use pumice
> or a thick cut brushed on and sand down to fill the pores? Any tips
> for dealing with the mill will also be appreciated

I discussed mixing in my last post, so I'll try to address application
here. There are really three phases to shellac application, and we're
talking the simple way of doing things, not getting into French
polishing or the like. In simple terms:

1) Build up a nice, thick, mostly even amount of shellac.
2) Let it sit for a week to cure.
3) Level and polish the finish

Phase 2 is the easy part.

Phase 1 is mostly concerned with building the finish. Assuming you have
prepped the wood and possibly applied a coat of some oil (I just use BLO
these days), you want to apply enough coats to build up one thick one.
Because of the nature of shellac, the coats are additive - each one
melts into and thickens the coat before it. This is quite unlike oil
based finishes, which react (usually with air) to form a surface that
does not dissolve with each new coat.

I'll explain what I do, but my advice remains the same - buy a book and
read it first. That's the best way to learn this stuff. If something in
the book confuses you, we'll get you through it. Read first, ask
questions later - it's really the best way.

Being a person with a short attention span, I tend to brush on the first
few coats to get going pretty quickly. After that, I pad on additional
coats until I think I have enough on there. You never sand between coats
with shellac. The thing to remember is that you are building a finish
that isn't going to be level yet, and you will (in phase 3) level it by
sanding it. So you have to get a pretty good thickness going. Luckily,
the stuff is so thin when you pad it on that it dries very quickly, and
you could easily do half a dozen coats in an afternoon on something
small like a box. Two brush coats and about six pad coats is probably
what I do on average, but it's pretty intuitive after you've done it a
while to know when you have "enough" on there.

When you have enough shellac on the surface and you have let it cure for
a week, you level it by running through increasingly fine grits of
wet-dry paper. It's kind of like scary sharp for finishes, although you
start with something fairly fine like 400 grit. If I see obvious drips I
start with 320, nothing coarser. Use a block of something for backing
and go over all the surfaces. The coarser grits really do the leveling,
taking off the high spots. The finer grits remove the scratches from the
coarser grits. At the start of this process, the surface will be shiny.
As you sand it should become uniformly dull. Any spots that still shine
mean you have a relatively low spot that needs to be reached and you
have to keep going. If you inadvertently remove all the shellac and get
down to bare wood, it means either you did a poor job of applying it to
about the same thickness everywhere or you stopped too soon and didn't
get enough coats on there. Not a problem really, just go back and apply
more, but you still have to re-do phase 2. This might happen the first
few times, just don't panic. Eventually you get a better feel for the
stuff and it won't happen any more.

When you get to the last grit (I go to about 1000 because that's usually
what I have around), you are done with the leveling and have effectively
moved into the polishing. You now switch over to finer abrasives -
pumice first, then rottenstone. I apply these with a cloth and use
mineral oil as a lubricant, but there are other choices. Basically
you're making a paste and rubbing all over the finish to remove the rest
of the scratches. I used to just do this with rottenstone, but it works
better with pumice first. You're still doing the same thing, using finer
abrasives to remove scratches until you reach a point where you can't
see them anymore.

This will give you a pretty reflective finish, if that's what you
want. There are ways to make it not so shiny. You have to read the
book for that one.

Did I mention you should go buy a book?

-Ken

Ken Greenberg (ken@c...) 667 Brush Creek Rd., Santa Rosa, CA 95404
http://www.calast.com/personal/ken/wood.htm Visit the oldtools book list
at http://www.calast.com/personal/ken/booklist.htm