Early Asian pianos

[Overs Pianos]

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Glenn, Andrew and other list lurkers,

In a message dated 6/21/2001 9:32:02 AM Central Daylight Time,
glenn@graftonpiano.com writes:


>. . . .The underlying reason why the polyester cracked
>is because they did not use a resin surfacer sheet on top of the
>wood. Yamaha does and as a result this type of damage is almost
>unheard of on a Yamaha. We have seen it on other pianos, including
>Boston pianos which lack the resin surfacer sheet.

But have a polyester film which is too thick.

Andrew Remillard responded;

>Thank-you for pointing this out.  I have seen this problem on a number of
>Asian pianos and 1960s European pianos and never new the cause other than the
>wood moving underneath the finish.

Its is also related the normal temperature gradients the piano is 
subjected to when combined with a polyester film which gets stressed 
if its too thick, on account of the temperature variation between the 
surface of the film and the inner body of the thick film. When this 
situation occurs, a process not dissimilar to the exfoliation of 
rocks causes the film to either crack, or to delaminate completely.

>I have seen it on an early Kawai, but
>your right, I cannot remember seeing it on a Yamaha.  


One of the main reasons why Yamaha polyester tends to remain on the 
piano, as opposed 'on the floor' in sheets, is that they tend to 
stick to their maximum recommended polyester film thickness (0.6 mm). 
The resin surfacer which Glenn referred to is more for the purpose of 
preventing the wood grain from showing through the polyester film. 
Many manufacturers have problems with cracked polyester because the 
film thickness is too thick. They do this to in an attempt to reduce 
sand throughs, but it can create a long term disaster.

Regarding stripping the old polyester, a heat gun and a good scraper 
will get it off in a very short time.

Regards to all.

Ron O.

PS. Thankfully, our piano's nearly ready. Might be able to get an 
overhead image up on our site soon (I'll let the list know when, 
where and if). The photo shoot was a couple of days ago.
-- 
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Website:  http://www.overspianos.com.au
Email:        mailto:ron@overspianos.com.au
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