[Dangee's Pyrography]

Hi Everyone!

Today a friend of mine brought me a burning to frame. It's 2ft by 2ft
in size, but the wood was severly warped.

Do any of you know of a way to flatten it out again? It's birch
plywood 1/4 inch thick.

How do you all store your plywood to prevent warping. Thanks...Dannie

[AlArchie]

Dannette, are you going to use commercial framing material or do you make your own frames? If you make your own, simply rabbet the relief portion of the frame to the same depth as the 1/4" ply. When the frame is assembled, insert the pyrography and back it up with another piece of ply that is the same size as the outside measurements as the frame. Force the backer down on the frame and either tack it down or glue it down. This will flatten the warped piece into the rabbet...problem solved.

If you didn't want the backer ply to show, you could make the frame 1/4" wider and deeper than normal, and make two rabbets; one for the pyrography piece 1/2"deep by 1/4"wide, and a second 1/4" x 1/4" above the lower one. Then the backer would be flush with the back of the frame and be hidden.

Maybe, if you are using commercial framing material, you could carefully apply epoxy glue to the relief in the frame, and then weight the pyrographic piece in place untill the glue sets. If you don't have weights avaialable, you could use several "C" clamps or even strong spring clamps to hold the pieces in place. Of course this would mean the burning would be permanantly attached to that frame.

Just a couple suggestions.

Al

[Dangee's Pyrography]

Thanks Al!
My husband makes my frames. I understand what you are saying, but this board looked like an archers bow! Wouldn't forcing pressure on the center of it crack it or split it?? Danette

[squbrigg]

Use the frame Al mentions, but first soak it. In a tub if you have to or wrapped in wet towels, really wet, warm/hot water, but soak the wood as thoroughly as possible, for as long as possible. 1/4" plywood, that will take a while to soak, but it will allow it to bend without cracking. Once it's plyable, insert it in the frame and secure, it will stay straight in the frame once it's secured. Plywood is best stored flat, if on edge it will cup/bow, unless it is supported properly.

Bob

[AlArchie]

Sounds like you might have a dillema! I doubt if flattening that piece of ply would cause any cracks, but my doubts are no guarantee. You could lay that piece flat and then GRADUALLY add weights to a cover sheet, flatening it a little at a time to see if it will take the strain.

Bob's suggestion may also work, but be carefull with the water treatment. Most plywoods, unless marked exterior, marine, or water proof, have water suluble glues holding the plies together. So getting the surface plies wet enough to be flexible without getting the glue wet could be a bit touchy.

The processes involved in manufacturing plywood vary a whole lot depending on type and grade, so there are accordingly varying types of plywood, depending on intended purpose. All however, as Bob mentioned, should be stored flat. A lot of this stuff, especially in hobby and art stores, is stored on edge to save space, so unless you pick your material up shortly after delivery, you run the risk of getting a warped piece.

One more question. Was the front surface of that piece sealed with varnish, poly, lacquer, etc, and not the back? If so that may have led to the warping, and any strtaightening may in fact not crack the ply but MAY crack the finish. Hmmmm......one more element to add to your problem.

I think I'd have a sit down with your friend and explain a few of the potential problems that may develop and see how she/he wants to proceed.

Al

[Hugh P.]

All good advice, something else to try. Put a damp cloth under the piece of plywood, warp down, place it in a warm spot with the sun shining on it. The heat and the sun will draw the edges as the moisture evaporates from under the wood.

[mark yundt]

Danette,,how severe is severe? If you lay it flat ,,and the edges lift off the surface,,how far up do they curl? A half inch,,an inch ,,or more? Knowing this can help.

One thing I personally would NOT do is to soak it. That to me is a potential disaster just waiting to happen.Getting it damp on one side MIGHT help,,but that can raise other issues.
The question about it being finished ( sealed in some way) on one side vs. the other I think is on target and might provide a solution,,as well as reason.Most plys that thin have usually have the thin outside veneers with probably three layers of wood between. Even wood that thin can put up a fight and want to move.

[Ashbys]

I agree with Mark .

Do not soak it . It is plywood, which means it is made up of pieces glued together to make the board. Without knowing the glue type it could eaisly come apart on you. If it is simple birch plywood , and bowed like that chances are is has been somwhere it could draw moisture, which caused the bow. If you put in a frame , the frame if it is strong enough to over come the bow it will hold it flat. Birch plywood is realtively cheap and most now is made overseas. Sometimes it is better to scrap it and buy new. A 4x8 sheet is about 22.00 for finsihed grade.

stoage of plywood the same as any wood, pallet flats under laying flat at least 3 inches above the ground .

[mark yundt]

Yeah,,ply isn't as stable as everyone thinks it is. Wood is wood and it's gonna move. Just playing with stuff around the shop,,heating one side,,burning on only one side,,finishing/painting/dampening one side,,it moves.Lay it on the ground and it curls away.
I have overcome this by scoring the opposite side on a table saw,,takes the fight right out of it. Take it a bit further and I make bending plywood. You can have it make sweeping turns right around a corner or make coves with it. Might just do the trick here to get it flat again if appearance on the back isn't an issue.
But at that size the usual cupping should come right out in a decent frame and will be held just fine in that final position.

[Dangee's Pyrography]

Thanks for all your advice. To answer your question Mark on how severe...if put on it's back the edges curl up about 4-5 inches on each end. The front of this wood has a beautiful wood burned picture on it...so I don't want to ruin the look of the burning. I will pass this on to my friend and have her try different methods out. Thanks again everyone! Danette