Plywood shrinkage??? Laminated soundboards???

[Sarah Fox]

Hi Ric,

> I dont know... but just THINK if they had been soundboard panels. One
> day the owner would come into play and find the Soundboard on the floor!
> I guess we'd better give up on the old plywood panel idea.

Dunno...  Is there anything different that distinguishes laminated
soundboards from plywood, besides the quality of wood, of course?

Assuming that there *is* shrinkage over time, this would be a problem for a
compression-crowned system, if such beasts (compression crowned, laminated
panels) exist.  However, for rib-crowned, it would be a lesser problem,
provided the SB doesn't shrink so far as to slip off of its support.  Of
course there would be a nasty problem of glue joint failure, and traction on
the SB (while still stuck) might diminish crown somewhat.

Has anyone else noticed shrinkage in antique plywood?  I did a quick web
search for "plywood shrinks" and found the following:

http://www.irbs.com/lists/live-aboard/0011/0130.html

which notes that plywood decking on boats typically shrinks and leaves gaps.
With another search, I found the following article about repairing antique
furniture with the "correct" wood that has already "pre-shrunk" for hundreds
of years:

http://www.kaleden.com/articles/3211.html

The article notes mostly shrinkage in width in solid panels and states that
this is not as big a problem in plywood panels that came into use in the
late 1800's.  The article infers that plywood shrinkage is not so
significant that a drawer bottom would shrink from its slots.  I beg to
differ, based on what I've seen, although I admit I see a lot more shrinkage
in the width of solid wood.

But what I wonder is whether total area loss in a solid panel is similar to
total area loss in a plywood panel, except along primarily one dimension,
instead of two?

Again, just curious...

Peace,
Sarah