One common problem people have with MonoKote is a too-cool iron or heat gun. The temperature of the iron should be just below the melting point of the material. The way I set up my iron is to dial it all the way up. After it's had time to warm up and stabilize, I touch it to a scrap piece. If should be hot enough to immediately put a hole in the material. I then dial it down a bit and wait for it to stabilize. I keep repeating the process until the iron is just cool enough that it doesn't dull the finish with its heat. If the finish dulls, you know the iron's still too hot. This is the proper temperature to get good sealing and shrinkage with an iron.

Many heat guns are also too cool unless you get right down onto the material. Again, with a piece of scrap, you should learn now close you have to get the heat gun to the material before it starts to melt the material. I've seen heat guns that were cool enough that you couldn't get a good shrink even with running the nozzle just off the surface of the material.

With a properly-hot iron and heat gun, getting the material to shrink and stay shrunk is easy and effortless. Of course, the different colors handle a bit differently, with the transparents and chrome needing more heat because they allow the heat right through or reflect it right back.

Where you have an overlap you don't want to come apart, a length of wet, rolled-up paper towel over the joint will prevent it from lifting up, as MinnFlyer mentioned.

(edit) I forgot to add that when the MonoKote ends at a rib, such as at a polyhedral joint, and the rib isn't capstripped, doubling it is a good idea because shrinking one side first will pull the rib and make it hard to get a good, even shrink in the bay immediatly inboard of the poly joint, as mentioned above.

bax