Whils trying to answer this question for myself I came across this thread;
http://www.bayarearidersforum.com/forums/showthread.php?threadid=145975Don't know how I missed it before, but it confirms all of my theories about the process. Very detailed indeed!
With regards sealing, ethanol apparently will attack epoxy. I keep hearing this. The chaps I know who deal with such things will only use this;
http://www.frost.co.uk/por15-motorcycle-fuel-tank-repair-kit-3193.htmlYou would need to use a layer of kevlar as well. I think some composite tanks also contain an unburstable bladder, not sure about the motorcycle ones but IIRC the car ones are often obliged to.
With regards layup, to retain the pattern of the carbon in the finished tank you need to make the top and sides of the tank as a single, split mold. The base of the tank, where it can't be seen, is typically made from a seperate single part mold. The two parts are then glued together, there's usually a small lip or overlap.
The other option is to use a lost core technique, this simply entails making a foam plug in the shape of the finished tank you desire and hand laying carbon over the top then wetting out with a brush, building up the epoxy and then flatting down by hand at the end. The plug is then disolved with acetone via the filler hole. This is a much quicker and simpler way of doing things and an excellent finish can be achieved with a lot of sanding and a good eye!