Hi, I am the one who originally sold Liquid Masking Film to modelers. I was introduced to it by Ivan Christensen from Cananda. I owned Fliteglas Models at the time. Bob Dively bought Fliteglas Models from me and my wife, Martha, about 25 years ago.
When useing LFM it is best to spray it on in one thick coat. Runs don't matter. Use a spray gun that puts out a lot of volume. If you get it on to thin it will not peel off the model. You need to clean the spray gun out immediately with water. Spray a bunch of water thru the gun. It is possible to brush or dab LMF on, but it works much better to spray it on. When cutting the pattern out use a #11 blade. Don't press down on the blade, the weight of the handle is enough to cut thru the LMF. I never tried to use LMF over open framework. I believe it can be done, but only after getting use to using LMF. Again the weight of the #11 blade handle is enough pressure to cut the film. Again if you get it on too thin it is almost impossible to get off. Practice on an old wing panel before using it on your new model. If you only want to spray a small area, tape off the area with masking tape and paper so that the edge of the area will have some thickness. When used correctly, there is zero paint bleed under the film. It leaves a line the looks like it was cut from monokote film.
If you have any more questions, I am glad to answer them if I can.

By the way, you can thin LMF with water but it only takes a very small amount of water. If you get it too thin it will run off the model and leave the finished film too thin.

Ralph White, Neoga, IL