RE: Frustrated with Covering
Coverings of any brand do tend to wrinkle when exposed to temperature extremes. Hot or cold.
This can be minimized to a great extent by your covering technique. It's a learned thing...I can't teach you here BUT...
Sheeted surfaces must be absolutely clean before covering. Vacuum, tack rag, then vacuum again. Keep your hands spotlessly clean while you work.
Do not "shrink" covering on sheeted surfaces. Use only enough heat to get the material to adhere, and no more. Work from the center of the surface outward. If you use the "meat wrap" technique to do your airplanes....wrinkles will be a permanent part of your life.
Open bay structures also must be spotlessly clean. Make every attempt to get the covering as wrinkle free as possible BEFORE heating/shrinking. Carefully smooth the material without bunching, and tack securely around the periphery of the open structure, before you try and shrink the material. Keep in mind that the more "shrink" you put in...the more that can come back out later.
It takes time, patience and a fair amount of practice to do great covering job that will actually STAY great.
Keep at it.