RE: Anyone using VARTM?
Vacuum infusion in RTM (Resin Transfer Molding) is a technique where the dry, cut fabric layers are stacked and bagged as normal, then the resin is added through one or several ports, which have valves installed, to retain the vacuum.
The vacuum draws the mixed resin into position, between the filaments of the stack. No breather mat or porous mylar sheet is used, since the resin is slowly moving from the infusion ports to the vac ports.
Some manufacturers also use a UV-sensitive resin in this process, which will not gain viscosity until special UV lights are turned on, to start the final curing phase.
It's becoming a more common method in Southern California and Florida yachtbuilding, where control of solvent volatiles in large quantities is essential, in order to comply with state and county regulations that involve out-gas emmissions from plastic laminating companies.