First off I am a painter for over 45 years. Used it all, Lacquer, synthol enamel, Acylic enamel, urethanes. Did a lot of custom painting with all of them. But I do have a question with the BC/CC urethanes. Instructions say base should be clearcoated within 24 hr's. I do know that there is a mid-coat clear that gives you up to 48 hr's from base to clear. BUT -- what is being done with some of these paint works that take longer to tape off the designs. Some of the paintworks we see must take a week or better to tape and prep, with all the colors that are used. This paint and clear today is very expensive and I'm sure a lot of garage painters would like to know what processes are being used for these multi colored paint jobs so they don't just go ahead and start taping and such over the base, wait to long, and have the clear start peeling after a short while. This new paint with the additives does not just dry, it chemically dries. If done wrong there will be problems. Might be a good discussion here ...
I tackle these in 2 ways. If the graphic is simple (one or 2 colors, or a fade, like flames) but a lot of time is needed to tape, shoot and un-tape. Shoot your color, seal with mid coat clear, let dry, scuff it well, then do your graphics, and clear it as soon as it's unmasked. This way the only "window" you're concerned with is the one for your graphic's paint. If doing multiple colors/maskings, you will have to midcoat some of the colors, sand, and shoot the additional ones, until you are ready for clear. Just be sure to clear the colors, as you don't want to sand the basecoats, just like on a regular paint job. The other way is to use an adhesion promoter instead of sanding. Sometimes this can fail on you though, so I avoid this method unless really necessary.
What I do for long term tapeouts is just apply 1 to 2 coats of clearcoat to the basecoat instead of intercoat clear. Then wet sand with 800 and apply graphics, flames, etc... and then just clearcoat over top of the graphics, flames, etc... and you will have a great, long lasting, top quality finish. If you want an over the top job, you can 800 the whole vehicle after applying the clearcoat on top of the graphics and reapply a couple more coats of clearcoat on top of that. Cut and buff it and it will look like glass. Good luck, VR&C.
I usually do multi-colour stuff like Voodoo Rod said with clear coat. It makes it easy to clean up any paint that ends up in the wrong place too.