Plastic Lakk

[gutlo]

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> From: Richard Brekne <Richard.Brekne@grieg.uib.no>
> To: PTG <pianotech@ptg.org>
> Subject: Plastic Lakk
> Date: Wednesday, March 14, 2001 11:20 AM
> 
> Hi List... ran into a piano today that had been dropped on its
> back and the owners claim that the laquer shattered as a result.
> There are certainly many long cracks in this very hard plastic
> laquer. Sort of like the long cracks a car window can get.
> 
> I dont work on plastic laquer so I am wonderering if anyone out
> there can tell me if these kinds of cracks in the lakk are
> repairable, or does it mean basically that the piano has to be
> stripped and refinished ? There are about 25 cracks  spread over
> the whole piano, ranging from say 8 to 15 inches in length and
> penetraiting the entire depth of the finish. In a couple places
> it is already starting to loosen from the wood and flace up.
> 
> 
> Anybody ???
> 
> 
> --
> Richard Brekne
> RPT, N.P.T.F.
> Bergen, Norway
> mailto:Richard.Brekne@grieg.uib.no
> 
> Richard,

Very likely this is a polyester finish.  Very hard, not very flexible, very
susceptible to "cold checking", which is what seems to have happened in
this case.  The more recent polyesters show better characteristics, but
still have this tendency.

Saw a new polyester Bechstein in Brooklyn 25 years ago that came in from
Chicago in the winter, 0 degrees, entered warm house, and the entire finish
cracked (soundboard coating included).  Bechstein refused to warranty,
customer had it refinished (in polyester again!) at their own expense.

PianoLac has been tested against freeze/thaw  by subjecting the dry coating
to 20 freeze/thaw cycles (8hours freeze, 8 hours immediate thaw) with no
damage.

I once fixed a black polyester Kawai upright with PianoLac.  It made an
invisible repair.  

Perhaps some Ultra-Thick PianoLac would work.  This is a very high
viscosity/solids version specifically for touch up.  If you'd like to try
this waterborne piano coating for your challenging problem, let me know.

Arthur Grudko, PianoLac (StarHawk Labs)