Fiberglass resin molds and more.

[Mr. Malloy]

I am new to fiberglass but am making some stuff and mold forming off of some plaster and other objects. For form making do I have to use the "fiberglass cloth"??? that is so expensive wont old sheets work? or towels? and I want a clear coat in some cases. I thought I was miss measuring so I carefully added the drops of hardener catalist several times and always end up with a brownish, hardly transparent stuff?? I got the cheapest fiberglass resine at home depot. The boat supplies shop has something that is CLEAR but costs 200.00$ plus per gallon. Much obliged for any input, thanks

[craigktx]

I am new to fiberglass but am making some stuff and mold forming off of some plaster and other objects. For form making do I have to use the "fiberglass cloth"??? that is so expensive wont old sheets work? or towels? and I want a clear coat in some cases. I thought I was miss measuring so I carefully added the drops of hardener catalist several times and always end up with a brownish, hardly transparent stuff?? I got the cheapest fiberglass resine at home depot. The boat supplies shop has something that is CLEAR but costs 200.00$ plus per gallon. Much obliged for any input, thanks

yes old sheets work well,i have only used them with epoxy.
i was making a RC sailboat mold.
do a test sample to see if the fiberglass resin will react with your cloth.
if you want a clear finish then you need to use fiberglass matt 6oz and epoxy.

[sculptor]

the last time i bought 15-20 gallons of resin, the clear casting resin was comparable to the cost of resin by the gallon at the lowes/menards---homecenter prices
then the hazardous material delivery upcharge was a tad dear-----(it's been a few years as i've been focusing on other pursuits)

to keep it clear---fiberglass is the only viable material i can think of

[grommet]

what about polyester resin as opposed to the stuff that says fiberglass? That is definitely clear.
weird that the stuff turned brown.. definitely the right catalyst?

[craigktx]

what about polyester resin as opposed to the stuff that says fiberglass? That is definitely clear.
weird that the stuff turned brown.. definitely the right catalyst?

its the same stuff.
if its been on the self to long it can turn an amber color.
fiberglass resin has a green tint sometimes.

epoxy can turn to an amber color also.

[The Forge]

The fiberglass cloth is what gives the fiberglass object the strength and flexibility using a very thin cross section. A sheet may not work because its threads are so tightly woven that it might not allow the resin to permeate the strands. The resin is two things- bonding agent for the threads and also seals the space between the threads.:)

[Mr. Malloy]

Thanks. I find, today that the sheet material worked but is not strong. I will try some old burlap bags that I have and try apoxy resin next too. The experiment went well though. The fiberglass resin/sheet came off of the piece I am making a mold of cleanly and without damage. I just coated the one side, trying for no under-cuts and its good for the one side. It is not strong though, its a bit flexible (which can be an advantage) but may break without a hefty mother mold before I use it for plaster casting. I also want to try for fiberglass product coming out of a fiberglass mold. Is that going to stick? I have just used parafin wax (2 coats) and then a thin layer of vaseline as a separator. It worked well on this manaquin arm. But ...

[raspero]

You really do need PVA mold release for casting a FRP (fiberglass reinforced plastic) object in an FRP mold. You can get it at any plastics store (places that sell fiberglass supplies and Plexiglas).

You can get by with wax, but for about 8 dollars why make life hard for yourself. Also you will get a perfect finish on your cast object using PVA. Vaseline works too, but it inhibits the cure of polyester resin, and the surface will remain a bit rough and sticky.

R