[pianotech] How to remove scratches

[Douglas Gregg]

Gregor,
You were doing traditional French polishing. It is much slower with
more steps and more drying. I can French polish a piano that is
scratched up in about 3 or 4 hours start to finish. Less time if it is
not too scratched.

I will differ a bit about French Polishing a polyester finish. It can
be done. I have done it and it looks good. However, if possible, it is
always better to sand and polish out a polyester finish if it has
enough thickness because it will be more durable than the shellac. If
you do French polish polyester, you should do the whole piece as it is
a slightly different sheen and is a little difficult to blend to the
polyester. There is no issue with adhesion. Shellac sticks to
practically any surface.

Doug Gregg
Classic Piano Doc


Message: 5
Date: Mon, 28 Jan 2013 14:49:28 +0100
From: Gregor _ <karlkaputt at hotmail.com>
To: "pianotech at ptg.org" <pianotech at ptg.org>
Subject: Re: [pianotech] How to remove scratches
Message-ID: <DUB104-W63D0C0C454F44C09F93D9CD4180 at phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"


Doug, thank you for your detailed answer. I am familiar with French
Polish. During my apprenticeship I completely polished some pianos,
but that?s more than 20 years ago ;-)  I was just wondering if that
K?nig stuff is something special or just shellac. Usually I would
prepare the surface by sanding and use oil for polishing and some kind
of pore filler (Bimsmehl is the German word, could not find a
translation for that) and after polishing I would use some benzoic
acid to remove the oil. But using a very special stuff in a one step
polishing procedure sounds quite charming :-)

Concerning removing scratches on poyester: no, French Polish does not
work. The best method on polyester is just very fine sanding (if
needed at all, depends on the depth of the scratches) and polishing
with a machine.

Gregor

------------------------
piano technician - tuner - dealer
M?nster, Germany
www.weldert.de