Mechanical Music Digest  Archives
You Are Not Logged In Login/Get New Account
Please Log In. Accounts are free!
Logged In users are granted additional features including a more current version of the Archives and a simplified process for submitting articles.
Home Archives Calendar Gallery Store Links Info
MMD > Archives > September 2001 > 2001.09.01 > 01Prev  Next


Piano Case Stain
By Karl Van Scyoc

Smearing tar (gilsonite/asphaltum) on your quarter-sawn piano case gives
a great appearance.  I noted that neither gilsonite nor asphaltum popped
up in the MMD archives search, so I figured I'd contribute a few more
terms.  Allow me to explain.

As a weekend pneumatic enthusiast, my re-building projects take a lot of
time, and I have plenty of time during the week to ponder different ways
to do my work--they are not always better or faster, but I always learn
something.  I have not been very impressed with off-the shelf wood
stains available these days, and got around to experimenting with
alternate wood colorants--particularly those that would have been in
frequent use in the early 1900's.

One such colorant was brought to my attention in Michael Dresdner's book
"The Woodfinishing Book".  He states:  "Although asphaltum is not easy
to find in art-supply stores, it is too good a material to pass up.  The
base of this tar-like gunk can be either petroleum or bitumen (coal),
but the colorant responsible for its beauty is a natural mineral called
gilsonite.  Use it as a stain on raw wood and you have a deep
brown/black color perfect for dark Jacobean or mission oak...."

I searched around art stores here, figuring that anything petroleum
based would be amply available in an oil town such as Houston.  Nobody
heard of it.

Finally, I contacted Ziegler Chemical and Mineral Corporation, a
processor of Gilsonite/Asphaltum and had the chance to discuss this with
a very knowledgeable sales person.  Check out their web-site -- it gives
a lot of product characteristic information:

     http://www.pioneerasphalt.com/gilsonit.htm

Their main customers buy huge quantities of the material, and a weekend
enthusiast won't even come onto their customer-base radar screen.  But
you can get it in relatively small quantities from their distributors.
Gilsonite is used for drilling mud, newsprint inks (it even smells just
like a brand new newspaper), and is essentially a roofing tar.  The
Ziegler products are based on a coal-like substance (rather than oil)
found only in Utah and apparently has better properties than the
petroleum-based cousin.

Properties of this material make it suitable only for oil-based topcoat
finishes such as an alkyd resin varnish.  Shellac or water-based
finishes will not adhere well according to their product information.
It is fairly colorfast (won't fade).  Have you ever seen faded coal?

I was advised to obtain a pre-made "cut" of gilsonite.  A cut is the
ratio of gilsonite to solvent--just like a shellac cut.  The recommended
product was number AA4047--this had the consistency of loose roofing
tar--or a very thick custard.  It is interesting that gilsonite behaves
more like a dye stain, as it goes into solution (not suspension) when
it's cutback.

Application of gilsonite is a rubber-glove activity.  Just dip any old
rag into the stuff, and smear it on.  I thinned my batch a little more
with mineral spirits to make it more of a gel.  It does have some
grain-filling capability, so a grain filler is not really needed, except
for particularly open grain.  You could easily mix the gilsonite as a
colorant to a grain filling paste--just make sure the paste is
oil-based.  I smeared across grain, and let it dry to a haze (10-15
minutes) and then used a clean cloth or 000 steel wool dampened in
mineral spirits to just remove excess.  On quarter-sawn oak,
conventional pigment stains can sometimes leave a too-pronounced fleck
(stripe), in my opinion.  As gilsonite behaves as a dye, the fleck is
muted, but clearly visible.  Since the resin varnish tends to soften the
stain, I applied a thin coat of varnish as a seal coat with very little
brushing in.

For those particularly adventurous, you can make your own cutback, but
the salesman advised against it.  To do this, you start with a bag of
rocks (crushed gilsonite) straight out of the Utah ground, such as their
product ZECO 11.  Shoot for a cutback of 37% gilsonite by weight, with
mineral oil as the solvent.  If you add 10% toluene or xylene, it will
accelerate the cutback process.  Dump everything in a closed, but
vented, container--well away from any structure and in a ventilated,
covered, area.  Stir every couple days.  In about a week the "raw"
gilsonite will be in solution.  If you are in a rush, you could heat it
mixture.  Zieglar use something like a pressure vessel with steam coils
to do the cutback.  Force the mixture through a filter to remove larger
particles that are not gilsonite (small pebbles, sand, etc.).

I managed to secure a gallon of AA4047 from their Houston distributor:

    Crozier Nelson Sales
    15710 JFK Blvd, Suite 180
    Houston, TX  77032
    281-219-1611

They have distributors scattered across the US (and world for that
matter).

A further note:  roofing tar found in the home improvement stores often
has fibers, particles, and may be synthetic.   Avoid using these
materials on your piano.

I was a little apprehensive about smearing gilsonite on my current
project, but I the results turned out very nice.  The biggest drawback,
by far, is the time needed to apply enough coats of slow-drying varnish
topcoat.


(Message sent Sat 1 Sep 2001, 14:20:44 GMT, from time zone GMT-0500.)

Key Words in Subject:  Case, Piano, Stain

Home    Archives    Calendar    Gallery    Store    Links    Info   


Enter text below to search the MMD Website with Google



CONTACT FORM: Click HERE to write to the editor, or to post a message about Mechanical Musical Instruments to the MMD

Unless otherwise noted, all opinions are those of the individual authors and may not represent those of the editors. Compilation copyright 1995-2024 by Jody Kravitz.

Please read our Republication Policy before copying information from or creating links to this web site.

Click HERE to contact the webmaster regarding problems with the website.

Please support publication of the MMD by donating online

Please Support Publication of the MMD with your Generous Donation

Pay via PayPal

No PayPal account required

                                     
Translate This Page