Fibreglass RESIN FOR 1KG PROFESSIONAL QUALITY ENCORE 30 a.k.a CRAY VALLEY This WHITE polyester fibreglass acts and behaves like other polyester resins but is pre-pigmented white. You can use it with fibreglass and other re-enforcements . It is also possible to use at as a casting resin but its worth noting that we would recommend a max pour depth of 25mm. Our advice is to always test first. Thorough mixing of catalyst into resins and gelcoat is very important. Also the correct additions should be observed to maintain good results. Dispensers are advised for accuracy. The table below gives the correct ratios of catalyst to resin and gelcoat by weight. 1% is considered a slow mix, 2% is ideal, 3% is a fast mix. Additions outside these bands in not advisable for proper curing, in fact adding more than 4% may result in a failure to cure.