RE: E-Flite Pulse XT 25e on floats wrinkling covering question
You are correct. What you are experiencing is water getting into the wood and loosening the covering. It only takes a drop of two and the moisture will travel along the wood. Unfortunately, each time you iron the covering down it will stick a little worse until eventually you will not be able to get it to stick down at all.
The cure is to be fanatical about sealing out the water. Buy a roll of Scotch "Gloss Finish Multitask Tape" or "Satin Finish Gift Wrap Tape" (not the regular scotch tape, it is not water proof) and tape over all of the covering joints that are likely to get wet. In particular, go all the way around the edges of the tail sufaces and wings and along the bottom edges of the fuselage. If the control surfaces are not already attached, tape along the trailing edges of the wing, stab and fin and the leading edges of the ailerons, elevators and rudder before you hinge the surfaces. If the control surfaces are already attached, you will need to use the tape to seal the top and bottom of all hinge gaps.
Then look over the entire airplane and try to imagine where even a single drop of water could work it's way in. Use the tape or thin CA to seal anything you find.
And finally, after each flying session, look over the plane for loose covering. If you find any, figure out where the water was coming from and seal the leak.
I have several float plane ARFs with three or four years of water flying on them and they still look new. It takes constant attention, but it is worth it.