I thought I'd add something to this thread five years on, as I tried a different approach to getting a gloss finish. This after struggling for weeks and stripping the gloss coat on a model that I had been working on for a few years. I think the Humbrol acryic gloss (said to be a substitue for 'Future') was incompatible with Tamiya acrylic paint or the latter had not dried sufficiently - even after weeks - because the Humbrol crazed and drove me crazy.
The 'solution' was to apply AK's 'glass coat gauzy agent' meant to 'clarify' windscreens and canopies - removing scratches, etc. I used it on the nose cone of a highly modified 1/12 scale Tamiya Lotus 49 F1. It has to be poured on an allowed to run off. I think I did the nose cone in three separate sections and was reasonably happy with result after all the frustration, though sorry I did not work harder at removing the masking line (or avoiding it completely.