Hi!
Sure, you can seal the wood, but I have seen the resin from poorly dried wood come through the sealer in a short amount of time. (It was less than one year.)
As for the foam core window... you can add stregnth by adding layers of mat board,in between foam core layers. The more layers the stronger, so use the 1/8" acid-free foam core.
I have done it in the past for exactly the same reason you are. (Don't you LOVE x-stitch?)
PLEASE!!!! Don't use staples!!!! If you aren't going to stitch the fabric, use stainless steel pins. Staples pierce the fabric and weaken it, while pins can be put in the fabric's holes. Unless the fabric is a linin (28 count or smaller), it is created with a weave that is sometimes called a "locking weave". Which means the threads are locked in place and should not pull out easily.
(Can you tell I do X-Stitch?)
------------------
Sue May
"Everyone is born right-handed, only the greatest can over come it!"
[This message has been edited by Susan May (edited November 17, 2000).]
[This message has been edited by Susan May (edited November 17, 2000).]