Hi,
I have a MVP spray lay-up system and I’m running into difficulties with air pockets forming in relatively sharp concave corners. Difficulties getting the material to sit down and expel any trapped air. I’m using fiberglass and have spent some time adjusting the resin-fibre ratio between wet and dry to find the best setting.
Wet seems to allow the material to “flow” better during rolling, reducing trapped air pockets to a high degree but the finish is not acceptable and pooling of resin is a problem (overheating). When dry I’m still getting air pockets, maybe I should dry abit dryer. The fiber length in the chopper is adjustable and I’m using 16mm stands of 2400 tex material.
Where ever an air pocket forms it causes the gelcoat to wrinkle so to eliminate this possibility I pre-spray the gelcoat surface with a layer of resin (polyester) and allow it to dry, that way the sprayed up reinforcement layer cannot directly damage the gelocoat surface, even if there is an air pocket.
I was thinking of manufacturing a new wheel which holds the blades in the chopper gun such that the strand lengths will be reduced to 8mm and may sit down better in the sharp edges. Any taughts would be appreciated.
I know vacumn baging will sort all this, but it shouldn’t be necessary. Looked at a good few complex sprayed-up pieces and they are flawless, so wondering where I’m going wrong !
Thanks for any help !
Joe