Please help keep large boards from warping...much

[TimberFace]

Hi gang,
I'm about to start a rather ambitious project and was looking for a solution to minimize warping before I begin. I did a search on the subject and mostly found info on reducing warping on glued panels. This project consists of large boards that are not glued together, but hanging from one to the next with eye screws/lags. There will be seven boards cut into the shape of a bison head. A landscape scene will then be relief carved into the entire shape. I have attached a rough drawing. (Very rough. This is just to give you the idea. Hopefully the actual piece won't look like a devils head.) For illustration purposes I left the boards at the 5 foot length but they will be cut away in the actual carving of the bison head.

The wood is white pine. I was told they are kiln dried to approx. 8% mc (moisture content). The boards are 8 inches wide and a little over 1-1/2 inches thick (before relief carving). The longest boards will be approx. 4-1/2 feet long near the top of the head. About 2 feet long near the bottom. The gaps between boards for the eye lags will be approx. 1-1/2 inches. The entire piece will hang approx. 5-1/2 feet long and will hang on a large stone fireplace.

There are a couple of reasons for the separate board design:
One is that the piece has to be shipped from Tennessee to Colorado. The other is that I wanted the stonework of the fireplace to be visible through the piece.

My concern is that these boards will warp to the point of looking ridiculous. I don't mind some slight warpage or minor cupping but I would like to try and keep them reasonable. Again, the piece will hang above a fireplace, adding to the extreme temp and moisture fluctuation. I considered angle iron attached to the back of each board if absolutely necessary. But that poses new problems with protruding screws, unless I used large bolts on each end and not try to hide them integrating them into the piece. It may add to the rustic feel.
Thanks very much in advance for any help or suggestions.
Lundy

[pallin]

If the boards are selected carefully for straight grain and placed in the overall design carefully, you should have very little warping. Be sure the placement of the eye lags eases any stress on the boards.

I did a similar wall decoration in redwood - See "Symmetry Drawing C" - backing the boards with perpendicular strips on the back. It is mounted on the front exterior wall of my house.

[mark yundt]

Lundy, check your PM's for a list of suggestions.

[TreeWizard]

Look at the end of each board and see which way the grain runs, then alternate them. First one up, second one down third one up etc.

[Hi_Ho_Sliver]

Like Treewizard said!

[brent]

I hope you show this at its completion. looks like an interesting idea.

[LisaS]

While alternating the grain on boards for glue-ups is standard practice in cabinet making, I can't see what difference it would make when the boards are not to be edge glued (unless I miss understand the application here). I would just make the cupping alternate between the suspended boards.

It seems like you have to look at this as a problem for the individual 5' by 8" boards to be hung on 1.5" spacing.

[TimberFace]

Thanks everyone.
Mark, Thanks for the PM. I tried to respond to your message but couldn't.
LisaS, That is correct, each board is completely separate from the other. So I have a total of seven boards possibly warping.
As far as cupping, I would rather all the boards cup the same way, convex out. But I'm actually more concerned with warping length-wise.
Thanks again.
Lundy

[livens]

A secret I learned when I first got into woodworking to prevent warping was "Whatever you do to one side, do to the other.". For example if you are making a desk top and apply 5 coats of laquer/shellac/poly to the top, also apply the same number of coats to the under side of the top. This way both sides will absorb and release moisture at about the same rate.

Warping usually occurs when one side of the wood absorbs more moisture that the other, and therefore expands more that the other side. But I have had some boards that warped because of internal stresses being relieved when cutting them. Not much you can do to prevent that.

I would also use some spacers on the back of the boards so they do not sit flush with the wall. Having a small gap, 1/8" - 1/4", will allow air to circulate behind it helping to equalize the moisture exposure from front to back.

Hope that helps