wouldnt use pva,take it your glassing a sheet of ply,first thing marine ply is ObViuosly best but good dry exterior ply is ok >wbpo from builders merchant is good
Take a cross cut saw and drag it all over the ply to make a series of crosses as rough as possible,then impregnate the ply with a coat of catalysed resin A let this go off then apply the chopped strand mat probably 1.5oz sq ft with necassary resin and make sure well saturated use an alluminium roller ,surface tissue and gelcoat /wax in styrene addative can then be applied,but dont know exactly what your doing.
Epoxy is better yes,provide humidity and teperature are right but polyester is fine
provided it is applied correctly
