On Sat, 18 Dec 2004 21:30:24 -0600, "bob"
wrote:

I am building a kitchen hutch out of primavera, also known as "white
mahogany". The wood was purchased from an importer with a kiln, so it is
kiln dried. I milled the wood to 3/4", glued up a bunch of panels roughly
16 inches wide, composed of 3 boards 5 to 6 inches wide. All was well for a
couple of weeks. Then, when I started assembling the hutch, I discovered my
panels are cupped across the grain - roughly 3/16 of an inch across 16
inches. Not all of them are cupped, but perhaps half of 20 panels are. The
moisture content is 12 to 14%, which seems high. I can't tell any
significant difference between cupped and uncupped panels. My genuine
mahogany and some oak, also stored in the shop, both measure around 8%.
I've noticed that the cupped panels will "uncup" over a few days, then
re-cup.

Any ideas why this is happening? Are the panels useable? I'm thinking not.

Also, when you glue up panels, should they be stickered while stored? I've
always just stacked 'em up on some sawhorses or whatever is handy.

This is the first time I've worked with primavera, so maybe it's just not a
good species to use for furniture...

Thanks.

Bob


I just experienced such a problem with a cherry panel. However, I
figured out that the heat register directly over my work in progress
had been blowing on it for a day, resulting in one side drying more
than the other, viola! Cupping! After a couple of days with cauls
clamped to it, it equalized and returned to flat. At that point, I
finished panel construction which in this case was to put breadboard
ends on it. That'll hold 'er.

So it is with your panels. They're drying unevenly. Keep them
stickered if you can't get them assembled right away. And that's the
best advise - What I try hard to do when I build solid panels like
that is get them installed/assembled together as soon as possible.
The resulting assembly with all it's glue and joinery properly done
ought to hold them in the shape you want.

And you ought to start with wood whose moisture content has stablized
to the conditions in your shop. The seller may have dried them then
stored them poorly, or not dried them right.