Polyurethane Finishes on pianos

[John Delacour]

At 12:55 AM +0100 1/1/02, Isaac OLEG SIMANOT wrote:

>I've seen one grand made with polyurethane (black) . It is not as good as
>poly , looks a little cheap, but it is a possible solution I guess.
>
>A bit heavy to spray, you may need a good sprayer.
>It does not seem to sand and buff so well as the poly.
>
>But the piano I've seen was acceptable, looks more as a lacquer than a poly.

There's polyurethane and polyurethane.  Obviously the straightforward 
polyurethane varnish and paints that have been used by DIY people for 
decades to the detriment of much good woodwork is not an option, by I 
understand that the finish on a Kawai, and probably a Yamaha is not 
polyester, as is generally thought, but a cured polyurethane.  Don't 
quote me on this, but I think my memory serves me aright.

A "two-pack" polyurethane is a very different product.  Whereas 
polyester is relatively harmless to the operator, acrylics and 
hard-curing polyurethane lacquers are lethal, spelling instant death 
to the operator if proper air-fed breathing apparatus is not used. 
For that reason very few small firms would want either the risk or 
the expense of using such products.  The advantage of polyurethane 
over polyester is apparent in the superior finish obtained by Kawai 
compared with the European makers, including Steinway, not to speak 
of American makers.

At one stage in my career I also experimented with an acid-catalysed 
melamine lacquer developed by a London firm.  The results were good 
and durable but I did not continue to use the stuff because it was 
quite unpleasant and, like all the other modern products, required a 
lot of hard work in flatting.  If I wanted that sort of working life, 
I'd have gone into the motor trade!  Every experiment has ended up 
with me returning to frenchpolishing, which is a noble art.

I'm at present working on a 102 year-old 6'7" black grand.  At least 
70% of my labour was done 103 years ago in Germany.  All I have to do 
is thoroughly clean and ease down the existing finish and commence 
the polishing work with the final body and finishing rubbers.  A job 
that might have taken 130 hours if I'd needed to strip, will probably 
take less than 40 hours in total.  Sadly this is possible only with a 
black piano.

Bonne année!

JD