general questions abt working with fibreglass

Heatshock

Hunter
hiya - very new to prop making
I am mostly interested in helmets and have been readin some info on using FG

I think I have the general idea is :
release agt
gelcoat
FG matt + resin

I tried some a few days ago - just to see wot I could do/use
just trying materials.
Just using a random mold, I used release agent, gelcoat, layered FG + brushing in resin.
result was - out side was nice and smooth - inside however; wasnt as smooth, had a few strands of the matt FG poking out - rough to touch and irritant to skin as well.

questions:
(1) is my rough interior just a matter of bad technique?

(2) how to solve rough FG interiors - a mate suggested gel coating the inside too! Or bondo and sand? Or sand FG directly? Some use rota cast polyurethane resin (wot is this stuff even? any got piccies or links pls)

(3) was follwoing DangerRuss WIP - he uses "shell shock" from smooth on and re-enforces with FG. I understand shell shock is a brushable plastic; when used this way - does it therefore substitute for the gel coating on the outside?

Thanks for lookin at questions!

Nate
 

stormtrooperguy

Sr Hunter
the roughness is bad technique... i learned that the hard way recently. you just have to be REALLY careful with the fiberglass matte, to make sure there are no barbs sticking out.

the others i can't help with.
 
If you do a good job at glassing anything, whether it is just a cast of something, there will be no rough interior. That comes with experience. However, if you brush gel coat over it, you will bury the sharp strands of fiberglass, and you will have a smooth interior. Do that when you are starting out, and when you have alot of experience with fiberglass, just go with gel coat and fiberglass, not any gel coat inside.
 

Heatshock

Hunter
thanks guys.
I thought as much that it would be inexperience/bad technique - was tryin to get a fine balance between just wetting the matt w/o flooding it. And ur right stormieguy - had random barbs sticking out - was worried that would be major issue with helmet interiors.

recently saw DangeRuss's interior of his Appleseed lid; and was "*** is THAT wot its meant to look like"

oh well, live and learn huh.

back to more practice!

Nate
 

Heatshock

Hunter
release agt? I use PVA - got the stuff from a boat repair place.

I know some of the sites say use wax + PVA - but I was just testing on a small item.
release agt shouldnt make a diff to interior though should it?
 

clonesix

Active Hunter
If you haven't already done so, please add a respirator to your list of supplies. It is important to protect your lungs from the hazzardous fumes.

For a smooth lay-up, a "J" roller will help. http://www.shopmaninc.com/fgrollers.html


For a really good interior finish, 1 layer of cloth over the mat will give you a smooth finish and reuce the threat of splinters.

For helmets, epoxy resin has lower odor than polyester.
 

evan4218

Active Hunter
I have found that the quality of the layup is greatly effected by the resin your using and the gel time. The cheap bondo brand stuff dosnt cut it. You want something that will give you a good amount of time to get all your matt in place and smooth out any rough areas.

Another thing that is a must is a mud coat to remove trouble areas where it will be hard to make the matt conform to the detail. You create this by using talc or polyfiber. I do not recommend using cabo-sil as it can cause cancer.
 

Heatshock

Hunter
wow thanks for all the advice guys - clone six, as always, good advice - but I am kinda paranoid abt that sorta thing - have had a dual filter + eye protection even when working with bondo and E6000 glue!!

Never even thouht abt the quality of the resin - I just bought a kit from this boat repair place and used the resin provided.

evan - when you talk abt mud coat - I guess u are talking abt mixing the talc into resin to make a little thicker?

Nate
 

evan4218

Active Hunter
Yes, either talc or polyfiber will work fine. Just keep adding it little by little till you get a peanut butter like consistency and use a popsicle stick or brush to trow it into the details that you feel will not laminate well.
 

stormtrooperguy

Sr Hunter
to piggyback on this... when is it appropriate to use matte vs. cloth?

my clone holsters aren't cutting it slush cast, so i'm going to try fiberglass tomorrow night, using whatever brands / styles are available at the local autozone, since i need them for sunday ;)
 

MandoMan

Active Hunter
Wait, talc as in baby powder? Or can I buy pure talcum powder? Sorry, just never had a reason to wander into the local Wallyworld and buy talc. :lol:
 

BOBA PHAT

Well-Known Hunter
FG cloth is stronger than matte, but it's very hard to get it to lay flat in a mold with a complex shape. Matte will conform to just about any shape. So when in doubt, just use matte. You're making holsters, not a boat hull.

BTW - cutting matte into small squares, then shredding it into loose fibers is a great way to lay up any shape. It's a good method for a hard shape, leaves no air pockets, and 2 layers is usually strong enough for most casts.

-Ryan
 
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