Gluing down warped back?

I'm building the latest model of a StewMac concert uke. It has laminated back and sides.

Getting ready to glue the back on. Noticed that it didn't lay flat and has quite a gap at the tail block - around 1/8". I'm worried that using the rubber band method to hold the back on while the glue is drying might not be enough pressure.

I vaguely remember reading that moistening wood and letting it lay in the sun will reduce warping. Kind of remember trying it once. Is this a valid method? Would it work with the braces already on?

Any tips to solve my problem are appreciated.

Thanks,

Sometimes just wetting the wood will swell it and right the wrong, no sun needed. I have done this with solid wood but not plywood.

I wouldn't try to take the warp out the wood with moisture. In such cases just take some clamps to flatten it down at the tail block. Don't be shy about using clamps to get everything down in addition to your rubber bands. It will be fine in the end. There should be no gaps on the back to the sides. None.

In the old stewmac kits the back braces were arched but the edges of the sides that received the back were left flat. The back was meant to be forced down onto the ribs. Rick Turner had a legitimate name for this sort of construction but it escapes me now. I make my tops this way as a regular feature, using a flat caul the size of the instrument to get the effect I want. Try using a flat caul under the rubber bands to force a fit. Dry clamp it to test it first.

I had exactly the same problem... the braces are arched, so I kept trimming the lining/brace fit and test fitting until it snapped into place just like the online video of the StewMac kit shows. The back is now slightly arched, and with a light inside the body, no light can be seen through the back/side joint (or top/side either).

Thanks for the tips, especially TimberTone's who is building the same kit. If needed, I'm going to try the wood caul "cover" over the back/top before gluing and wrapping with the rubber bands.