Good Morning!
Actually, in reading these latter posts, I am realizing that there's a
bit of information missing.
Unless things have changed a good deal (always possible in this
business), most polyester finishes on pianos are not (usually) applied
directly to wood surfaces. Rather, there is a thin layer of fiberglass
which goes on first. It is applied, allowed to cure; and then sanded an
polished to where a polyester finish will not only "take", but adhere.
Understanding that I am neither a chemical nor mechanical engineer, I
_think_ that the reasoning around that is that, to a certain limited
extent, the fiberglass mitigates the various changes in dimension
between the wood core and the poly finish.
...Of course...it goes without saying that I could be wrong...it's
happened enough over the years to be noticeable.
Kind regards.
Horace
On 3/5/2018 3:32 AM, Jon Page via Piano Technicians Guild wrote:
> Please do not forward this message due to Auto Login.
>
> Just got electricity back after two days. You don't know what you've got till it's gone...
>
> Yes, something happens in the process. Much the same as Yamaha and some other brands have keys that crack because of the wood expansion. But that is from a rigid glue line, a more flexible bond would not have the problem. I can't imagine an interface between wood and ??a a plastic finish to avoid this.
>
> ------------------------------
> Regards,
>
> Jon Page
> ------------------------------
> -------------------------------------------
> Original Message:
> Sent: 03-03-2018 07:59
> From: Peter Grey
> Subject: Hamburg "D"
>
> And the poly is unable to move with the wood, right?
>
> Pwg
>
> ------------------------------
> Peter Grey
> Stratham NH
> 603-686-2395
>
pianodoctor57@gmail.com <
pianodoctor57@gmail.com>
> ------------------------------
>
> Original Message:
> Sent: 03-02-2018 15:40
> From: Jon Page
> Subject: Hamburg "D"
>
> I think cracks form when the piano freezes. Dissimilar materials (plastic/wood), different expansion rates.
>
> ------------------------------
> Regards,
>
> Jon Page
>
> Original Message:
> Sent: 03-01-2018 16:04
> From: Roger Gable
> Subject: Hamburg "D"
>
> I have a customer who is looking at a Hamburg 1998 Steinway "D" that arrived here (Seattle)??from New York. This piano has a polyester finish with large expansion cracks on the lid. My question to our East Coast technicians; are large compression cracks common on S??????teinway polyester
> finishes living on the East Coast?
> Roger
>
> ------------------------------
> Roger Gable
> Gable Piano
> Everett WA
> 425-252-5000
> ------------------------------
>
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Original Message------
Just got electricity back after two days. You don't know what you've got till it's gone...
Yes, something happens in the process. Much the same as Yamaha and some other brands have keys that crack because of the wood expansion. But that is from a rigid glue line, a more flexible bond would not have the problem. I can't imagine an interface between wood and a plastic finish to avoid this.
------------------------------
Regards,
Jon Page