Crack fillers - old soundboards

[Delwin D Fandrich]

----- Original Message -----
From: "Wallace Scherer" <p003520b@pb.seflin.org>
To: <pianotech@ptg.org>
Sent: April 28, 2001 12:55 PM
Subject: Crack fillers - old soundboards


> Has anyone out there tried any innovative approaches to sealing cracks in
> soundboards on old, cheap, baby grand pianos? I'm thinking about
> something on the order of a medium thickness CA glue, or some other
> liquid type of material that would fill in the crack.

It will be a good thing for the industry when many of these CA repairs being
done today begin to fail -- as they surely will -- and we can finally get
off the kick of using it for everything except tuning the bloody things.

There are more appropriate adhesives available for the type of repair you
have in mind. Epoxy -- with or without a variety of fillers -- has been used
successfully for at least thirty years for soundboard repairs. It is
relatively easy to do, albeit a bit messy, and the material has enough
inherent flexibility to not fail in practice.



> My customer has an old Winter baby grand with about 10 cracks in the
> soundboard, but none are very wide, not even paper thickness. She doesn't
> want to spend much money
> and is willing for me to experiment some. But I thought I'd better see if
> anyone else has experimented first.

Since the soundboard needs to be replaced anyway and repairing the visible
cracks is only going to be cosmetic, why bother filling them at all if price
is that important issue? Filling cracks in a soundboard--regardless of how
it is done--has essentially no effect on the musicality of the repair (and
certainly none that will last any appreciable time), so why not just leave
them alone?

Or, if cosmetics are important, color a bit of reasonably thin and
slow-setting epoxy to approximately match the color of the soundboard, run a
bit of masking tape along the sides of the cracks and flow the epoxy on
along the surface. Let it sit for a while--minutes to an hour or so,
depending on the brand and kick-over time of your epoxy--and check it over,
flowing on more where necessary. Monitor the curing process and just before
it gets fully hard run a chisel along to clean off the excess (both top and
bottom--with luck the epoxy will have crept all the way through the crack
and will be almost dripping out the bottom) and pull off the tape. When
fully cured, strip and/or scrape the surface and finish as desired. If
you've lucked on your coloring you'll barely see where the cracks were.

Since you are in a relatively humid climate it might be a good idea to drape
a blanket or two over the piano and put a space heater down below to dry the
board out a bit before beginning this process. You're not going to 'restore'
any crown, but you will open up the cracks a bit an make the filling process
easier.

Del