Wood & Moisture observation

[beagles]

I am currently making that woman's dresser. On Wednesday, I completed the glue up for the two sides. They are roughly 20 x 30 x 11/16 cherry before I trim them to size.

On Wednesday, they were nearly dead flat. I left them laying flat on my workbench over night. One on top of another.

I came down today, 18 hours after glue up, to find the panel on top had about an 1/16 - 1/8th inch cup. The one underneath was still flat.

Do you expect the wood would react to a moisture difference that quickly? BTW, it is about 10 degrees outside but the humidifier on the furnace is running.

Anyway, I placed the panel facing a heating duct outlet... and the panel returned to flat after about 2 hours.

I was planning on finishing both sides of the panel equally to slow down the moisture movement into the wood and hence its movement. Do any of you take the time to do that?

[Ruffnek]

When you glue up panels with PVA glue, you are introducing moisture to the wood.

I made the mistake of gluing up a Mesquite tabletop once and since I was leaving soon for two weeks offshore, I clamped the panel down to my assembly table, thinking it would help keep it flat.

Now, Mesquite is perhaps the most stable wood I know of but when I returned home, the panel had warped so badly that I had to rip it apart at the glue lines, joint, plane and re-glue the tabletop.

This time, I made sure it would get air circulation to both sides while the glue dried.

On any large panel, I would (and do) apply finish to both sides...not always equally but enough to slow the moisture transfer during humidity changes. IE, I may put a half-dozen coats of finish on the good side but only three or four on the underneath side.

[beagles]

Cody...

Thanks....

The glue up had 4 boards. I glued boards 1 & 2 and 3 & 4 with PVA glue earlier. I then ran each pair through my planer alternating sides to remove the last 1/16 inch.

I made the final glue-up using gorilla glue because I did not want the PVA to affect staining down the center of the panel.

BTW, I did leave one of the 1st two "half panels" on my TS top... and the PVA joint left a thin line of rust behind. Time for some steel wool and rewaxing. Ya lives and ya learns...

[dcarter636]

That is why you never leave panels laying flat on anything. Keep them upright or leaning against something so that both sides are exposed to free air until they are constrained in an assembly.

Same holds true for for boards, I try to keep them on edge and stacked crossed rick style, or if they must lie flat, with stickers.

[Beamer]

Jim,

I had exactly the same thing happen with 4 cherry panels a few years ago ... the good news is that I was able to slap together a quick rack out of 2x4's to hold the panels vertically for a few days and they equalized again and returned to mostly flat. Thank goodness, too, because i had as much as 1/4" of cup