Hi Everyone:
I am a 5+ year modeler and this is my first post - although I have contributed to the Model Railway Forums. My current interests are WWII aircraft and ships.
Like many people I have struggled with canopy masking. I have tried with varying success all [I think] techniques - pre-cut masks from Eduard or E-Z Mask, metal foil, Parafilm, Tamiya tape, 3M vinyl tape and even cutting very thin strips of painted Tamiya tape and just putting this directly on the canopy frame - looks OK on a 1/48 model. The small 1/72 scale fighter canopies are especially challenging but I have come up with a techniques that so far is working quite well.
I first cut thin [ <1mm ] strips of Tamiya tape. I do this by placing the tape on my cutting board and then cut with a steel ruler and hobby knife. I then place these strips on the canopy at the outline of the canopy frame pattern. While this isn't new, most references suggest using a sharp hobby knife to trim the tape at frame intersections. I have found this very fiddly and the tape frequently moves while cutting. What I have found is that by using a rotary cutter this process is much easier and can be done very accurately. I fill in the interior of the canopy frames with small pieces of Tamiya tape - you could also use liquid mask -if you're careful.
The key is the rotary cutter, which does use a sheer action for cutting. The one I use is from OLFA [18mm size] and you can get these from Michaels. I find that you can be very precise and if you do make a mistake you can just remove the tape and start again. You do not have to use much pressure to cut the tape - just 2 or 3 light strokes back and forth and remove the small pieces with a sewing needle and/or needle nose tweezers. This technique works just as well on the softer vacuum form canopies. I haven't tried the rotary cutter with metal foil yet but I will when I next get into a 1/48 model - although you can get a pre-cut mask for most of these.
Hope this is useful to others.
Alan