What this does is it raises the surface tension again slightly. So if you are using the GC50 which is formulated to be thixotropic and avoid sagging/separation, it makes it a lot easier to get a good application, even on vertical surfaces. Are you able to spray the GC50 at all? That really does make it easier. You should be able to brush the GC50 using the semi-perm/wax combination as well, but the issue then is its very difficult to get a smooth finish with a brush, and you can end up distorting the weave of your carbon which creates an odd appearance under the gelcoat. I'd really recommend spraying any clear in-mould coatings. 

OK, I have several things to lay up, some are relatively simple and flat, one has several return surfaces in a 3 part mold which means that it will always have at least one vertical surface and possibly even an "upside down" return to close it off.  If go down that route then I guess the easy lease wouldn't be suitable.  What would you suggest?  PVA?  Wax?

Thanks again for your input.

GC50 can be vac bagged fine. The issue with bagging polyester resins is when laminating with them, you can boil the styrene off under vacuum which causes problems with curing. No issue with GC50 or other gelcoats as you let them cure before laminating. 

The easy-lease isn't a necessity, I can use other release agents if you think others would be better suited, it's just I had heard positive things about it so thought it worth a go.

I might give that GC50 a go then as I'd like an aesthetically pleasing finish if possible.

Do you know if the GC50 can be vac bagged?  I'd heard that some polyester resins aren't suitable for use under vacuum.

Alternatively, brush the laminating resin into the mould and proceed with laying up the carbon. Make the first layer quite resin rich, then do the others as normal before bagging it all up. 

Hi, I've been reading through the forum but can't find the specific answer I'm looking for so wondered if anyone could advise?