plaster cloth and fiberglass?

I know this probably sounds like a dumb question, but Ive not actually been able to find any information about it online so i thought I'd ask: Im currently working on a diving helmet for a Bioshock Big Sister. The pattern is from EVA foam and ive already built it, but I want something more solid. ive tried partially coating it in fiberglass cloth and resin and it works great for what I need however it does leave a lot of sharp edges and doesnt get into the corners from the round helmet areas to the flat sections where the windows will be mounted as easily as I'd like. My question is, can I go over it in plaster cloth to strengthen it, shape it around the finer points and then once thats dry go over it with fiberglass resin? I dont care much about weight, as long as it isnt ridiculously heavy as its currently light as a feather and being a diving helmet, the weight is distributed onto my shoulders and back rather than on my head. Solid is what im going for, if its a bit heavy so be it. Would this be a viable option since plaster cloth is easier to work with and form into curves than fiberglass cloth? would the resin even penetrate and hold adequately? or am I better off just to fully cover in fiberglass cloth and bondo it?

Hi SerpentineSylph

Can´t you sand down the sharp edges?..wear a dust mask and do it in a ventilated area, nasty dust there...if you do so.

"and doesnt get into the corners from the round helmet areas to the flat sections where the windows will be mounted as easily as I'd like"

This is part of fiberglassing, adapting the material to shapes.

¿What kind of cloth/matt are you using?. If its matt (what should be in this case and in my opinion), which onee? 15,200,300 g ....more could be too difficoult to adapt.
You could also use veil, a thin tissue like fiberglass fabric.
The process when fiberglassing should be like this :
Brush plain resin over the surface, put on fibrgl....you can "mistreat" it a little to weaken it and make it more adaptable. Then resin again over the dry fbgl....wait or move to another area...go back and work with the brush over it to adapt it. No more resin on the brush this time.
This way the resin ande gravity will do part of the job, it someway "disolves" (not sure if this is chemichaly exact) the fiberglass making it easier to adapt.

Plaster bandages over fiberglass, doesn´t sound too orthodox. It can be done, why not but it sounds llike fixing a problem with a low rate solution.

Don´t forger there´s bondo (polyester body filler used in automotive industry) to repair fiberglass. Or for example, if you think there might be areas difficoult to adapt, use some bondo to fill them and it will be easier to adapt the fiberglass.


Another option could have been brushing layers of PU resin (smoothcast roto 65d for expample). Cleaner and easier.

This is a bad idea on every count. leave your foam helmet as is, and build a new helmet starting with an acrylic hemispheres. You will be light weight and it will be less effort than trying to coat something in fiberglass, and then bondo'ng it smooth.Fiberglass and Bondo over anything to try and sand down a shape is a LOT of work, and should be avoided

I agree 100%, when I read "helmet" I was thinking of something different...now that Ive seen it, two acrylic halph spheres or similar are the way to go, and the parts and decoration could be painted EVA foam, not much more. Much easier.
In fact, my comment was written thinking of a situation where there´s no way back as the fiberglass is already there.
But if there´s a chance to start again...

Acrylic Domes http://www.eztopsworldwide.com/smalldomes.htm