Whenever I need to do a complex masking job, such as curves, over paint, just windows, etc., I run into problems. Usually the worst problems are paint lifing and gummy spots left behind. I've tried frisket, liquid mask, and plain old masking tape. What do you use?
I'm nearing completion of my first model after a break of some 20 years, so I'm learning things all over again. Anyway as far as masking tape goes I am using a tape called Scotch 'Pressure Sensitive Tape' also known as 'Low Tack' masking tape, I got this from my local art store. Others will tell you that Tamiya tape is the best. It may be but it is also expensive, and so far I have had no trouble with the Scotch tape i.e. no paint lifting and no tacky residue left behind.
I also use Humbrol Maskol as my liquid mask. This is latex based so I guess that any latex based product will do. To apply it I use a tooth pick. As a experiment (to which the result is unkonwn at the moment because I haven't finished painting) I have used both Maskol and maskibng tape on the canopy of my Tomcat to see which gives the better result.
To put the masking tape on the canopy I first cut it roughly to shape and then burnished it down over it so that the canopy frame could be identified through the tape. Then, with a new No 10 scapel blade, I carefully cut around the frame and remove the excess tape.
Applying the Maskol I found to be a litte easier because I let the stuff run up to the frame edge and then wick along the edge before smearing it over the rest of the canopy.
It does take time and patientce and it took me three attempts to get the Maskol just right.
A common masking mistake is to use 3M masking tape as opposed to 3M drafting tape. The former is high tack with heavy residue. The latter is low tack with minimal residue. An even better improvement over drafting tape is Tamiya masking tape - low tack, very flexible for compound curves and comes in plastic dispensers of varying width. There are refills available for the dispensers.
I am also using Parafilm more and more. I tried it several times in the past and didn't like it. Then I discovered that the key to my use of it is to stretch it in four directions (left, right, up and down) instead of the two directions (left & right only) I had done before.
A trick to masking any tape over curves is to cut small "nicks" in the tape at small intervals. Don't cut all the way through the tape but only about one-third to a half way through. The cuts allow the tape to bend without wrinkling. This is a great method for bombs, drop tanks, fuselages, etc.
I use ordinary Scotch tape myself which leaves no glue behind. But I do have tape that does leave glue behind. So it is a matter of picking and testing the right brand. In my experience paint lifting can for a large part be prevented by de-greasing the model prior to painting.
I use Tamiya masking tape here in Japan, where it is not too pricey. I used a generic-brand masking tape back in South Africa. As time went on, I tended to cut the masking tape very very thin indeed with a scalpel on a glass surface, which allowed for masking of very complex areas - or rather I should say the edges - plus the adjust ment of the tape was easier to carry out (using a toothpick) than would be the case for thick-cut tape. After this, the interior of masked areas was filled with a liquid mask (Humbrol or Tamiya in my case). the above refers to canopies; for larger areas such as wings, hulls and the like, I would use thicker-cut masking tape against the thinly-cut tape, and after that paper to fill up the rest of the interior. Lots of scrap paper from the laboratory/office was used in this manner.