can the resin used in fiberglass be used for casting??

keithktam

New Member
i read someone used the resin (just the resin) to harden a papercraft helmet, i wonder if such can be used to cast something out of a mold??
 

Nwerke

Master Member
Yes but don't. It's stinky, sticky and produces nasty results. It also gets hot enough to burn while curing if you make anything more than small thin pieces.

Use polyurethane casting resin instead. It is ten thousand times better.
 

Jedi Dade

Sr Member
Poly urethane casting is more "civilized".

But I know some people that cast almost exclusively with fiberglass resin.

If you're going t do it... large well ventilated area - the fumes are literally a killer.

JediDade
 

ILL GREEN

New Member
Look up Rondo. That would be more suitable for casting than the fiberglass resin alone. Its a mix of Bondo Fiberglass resin and Bondo Body filler and you have to add both activators of each product into the mix. 8 drops per ounce for the resin and 6 inch of activator per ounce for the Body Filler.

It stinks and the most foulest mix in casting but its great for rotocasting when on the cheap.

And I only recommend Rondo for slushing and rotocasting because pouring it in to make solid parts will burn out your mold from the intense heat.
 
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tsenecal

Member
there are two types of resin commonly used for fiberglassing. polyester and epoxy. polyester stinks and heats up... the thicker the object, the hotter it gets. epoxy resin's smell is much much much less, (you could use it in your basement with a couple windows open) and doesn't heat up during curing. epoxy resin is more expensive than polyester. epoxy resin doesn't cure as fast as polyester. both fiberglassing resins are thicker than the resins made specifically for casting, which is important. the closer to water consistency, the better off your casting will be... higher fidelity, fewer bubbles.
 

keithktam

New Member
thanks guys!! but do they last long once the "can" been opened (and closed back of course)?? because the kind of resin used by garage kit company has a short life once opened, thats why i am considering something alternative, and cheaper....
 

Nwerke

Master Member
I'm still casting fine with urethane I opened about eight weeks ago. Sometimes the only way to decide is to try it both ways. You might get results you like well enough for your purposes with the cheap stuff. If you have family around, they will complain, though! I think polyester is usually a false economy.
 

keithktam

New Member
I'm still casting fine with urethane I opened about eight weeks ago. Sometimes the only way to decide is to try it both ways. You might get results you like well enough for your purposes with the cheap stuff. If you have family around, they will complain, though! I think polyester is usually a false economy.
thanks!! but let see if i can get that epoxy thing from the store, wish me luck :)
 

clonesix

Sr Member
i read someone used the resin (just the resin) to harden a papercraft helmet, i wonder if such can be used to cast something out of a mold??


NO. DO NOT DO THIS!!!!!!!

Is that clear enough?


Sorry for the bold, but this IS pretty serious. Fiberglass resin (Commonly 'Polyester' resin) cures by heat, and can ONLY be used in thin layers. The Greater the mass, (read "thickness") the greater the heat!

If you were to leave polyester resin in the cup after the laminating was finished, anything more than 1/2" deep in the cup will get super hot, release very TOXIC fumes, and possibly start a FIRE!

Polyester resin should ONLY be used for laminations!

Urethane is what you want to use for casting. You can also used it to stiffen Pepakura, if you want, but it will ruin a brush each use because you can't clean the brush of cured resin.






 

32buds

Well-Known Member
I like this post. It shows that others on here know there stuff regarding resins. Many years ago "I n a galaxy far far away", before becoming self employed, thereby avoiding the whole exploitation trap, I was a glass fibre laminator. Hand laying shower trays! Indeed, the resin doe's give off VERY nasty fumes. It was essential to wear a filtered breathing mask and lots of protective clothing(gloves etc.) The resin gets quite warm during the curing process, which is caused by adding an accelerant to it, in a measured dose. On average 10 kg of resin mixed with 10 ml of accelerant would give you approximately 40 minutes working time, after which the resin would very quickly thicken and harden.
As an experiment, one day I placed a bucket filled with 10 kgs of resin. That's a bucket roughly 30cms wide by30cms high in case anyone didn't know. To that I added 200ml's of accelerant. The accelerant is an organic peroxide. If you spill it on your skin it will burn to the bone! You will feel an itch after 5-10 seconds and then the pain kicks in-not pleasant. I've seen workers being stupid and not wearing eye protection. Believe me, eye contact is not pretty or painless.....
Anyway, back to the experiment. 200ml's is far too much, but I was curious. After roughly 5 minutes the resin was completely hardened and giving off a lot of heat. Then it started crackling and splitting, with smaller pieces splitting off and being thrown from the bucket. By this time thick brown smoke was issuing from the bucket, which was beginning to melt!
Shortly after the smoke turned black and flames were seen . That was when the bucket exploded very violently, hurling fairly big chunks of burning resin in all directions for a distance of about 10 feet!
Follow the instructions of other experienced modellers on this site and PLEASE DO NOT USE THIS RESIN!
 

keithktam

New Member
wow, thanks. :facepalmi can only imagine if i didn't come to this website by compulsion, in an alternate universe, i might lose everything in my life, including myself.... cause i live in a very small apartment, and would likely to leave the resin to cure while i was on to something and someplace else...

so big big a thank you to all of you, the wisdom giver!! I won't forget you!!

:)
 

alienbuilder

Well-Known Member
hello, I am not as experienced with resin as the others here, but worked a little bit with all three kinds: polyurethane, epoxy and polyester. in my opinion, as many other stuff we are handling in our life these are all toxic, at least the hardener. its just a fact you should have in mind. so, to use them outdoors, or in a workshop with the windows wide open and also using an carbon filter mask is always a good idea. bud I dont do that all the time too, though. the fact something smells less, dosnt mean its less toxic:)
well for the question itself as I said, I m not really experienced, just can tell that polyester really heats up and cracks, but I know some that is special for casting and is much slower. there are many types of every stuff. epoxy gets warm too if it is a fast one I think just as polyurethane does. but, for casting I liked polyurethane the most, because its a little but more stabile because its a little bit elastic so it wont crack so easy. and the surface is much better with less bubbles. and its easier to work with because normaly its just one part hardener and one part resin. i would say the price difference is not too much.
 

keithktam

New Member
hello, I am not as experienced with resin as the others here, but worked a little bit with all three kinds: polyurethane, epoxy and polyester. in my opinion, as many other stuff we are handling in our life these are all toxic, at least the hardener. its just a fact you should have in mind. so, to use them outdoors, or in a workshop with the windows wide open and also using an carbon filter mask is always a good idea. bud I dont do that all the time too, though. the fact something smells less, dosnt mean its less toxic:)
well for the question itself as I said, I m not really experienced, just can tell that polyester really heats up and cracks, but I know some that is special for casting and is much slower. there are many types of every stuff. epoxy gets warm too if it is a fast one I think just as polyurethane does. but, for casting I liked polyurethane the most, because its a little but more stabile because its a little bit elastic so it wont crack so easy. and the surface is much better with less bubbles. and its easier to work with because normaly its just one part hardener and one part resin. i would say the price difference is not too much.
thanks!!!
 

Galane

New Member
The first castings I attempted, late 20th century, I used water clear polyester resin for encapsulating and casting. I also used some red dye for polyester resin. Took the entire vial of dye to get a half quart of resin dark enough. For molds I brushed many coats of latex onto the original lens, then made a fiberglass support shell. (I was doing this circa 1995, before I had Internet access.) Eventually I got a pair of 1952 Hudson Wasp tail light lenses made, the inside surface with all the detail came out pretty good but the outside was rough and had to be sanded and polished. Didn't do more casting until circa 2001 when I found RTV and urethanes - but it took me a while to get around to doing...

Pressure casting, it's easy, inexpensive and no bubbles. http://partsbyemc.com/pub/mold-making.htm Harbor Freight has the 2.5 gallon pot for $100 and a "pancake" air compressor for $60. Add a few more $ for the second pressure gauge and 1/4 turn ball valve and you're set up for under $200.

The other stuff you'll need; some SHARP knives, modeling clay, an old saucer, a mug warmer (saucer and warmer for softening clay), a hot glue gun, some corrugated cardboard and packing tape (to cover the cardboard if you can't get shiny cardboard), and an AC powered rotary tool (Dremel or similar) with a selection of cutting wheels and grindstones. Cordless rotary tools or those cheap ones that run off a wall wart are not powerful enough to cut and grind RTV silicone. You'll also need mold release suitable for the silicone and resin you choose.

I still use a few of my silicone molds made without pressure casting them. The bumps on the castings are either in areas that aren't important or they're little balls that easily snap off. I should re-make those molds but they're low-demand castings.
 
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