I recently read Gary Jones' article #7 in Kitplanes Magazine regarding building the wing for his Glasair II and I read where he used a little "trick" to keep the fiberglass mat in place when closing the wing. Something didn't seem right about his trick, upon further reading I see that he had numerous leaks in his fuel tanks ... I think I know why.
First, let me say that I have not closed my wing yet so I am not an expert in this area... I'm just stating what I see as a real bad idea that looks to me like it could cause alot of leaks in your wing.
In Gary's article he states that in order to keep the cloth mat on the spar cap and around the extra fuel cel from moving he used a syringe and applied a bead of resin down the center of all of the matting cloth the night before he was going to close the wing and allowed it to cure. At first glance this seems like an OK idea, it will keep the mat from moving.
However, it is my understanding that when you close the wing and add weights to the upper surface of the wing you are causing the fiberglass mat to compress and therefore conform perfectly to the two mating surfaces and provide a good bond with few or no leaks. If you apply a bead of resin down the center of the mat you will end up with a hardened, 1/8" thick (not compressed and non-compressible) strip of map that the upper wing skin will rest on and not allow any compression or resin squeeze-out.
I think using Gary's "trick" would yield the same results of laying a line of 1/8" wooden dowels along the top of the spar cap and fiberglass matting fore and aft of the dowels before closing ... does not sound like a good idea huh? I'm just illustrating a point that his bead of resin creates a "solid object" down the center of the mat.
Here is an image from Gary's article showing him applying the bead of resin.
