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japcarmaniac
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i have recently purchased supplies to create my own carbon parts. i have purchased a polyester tooling gelcoat then was advised i should have choosin an epoxy gelcoat. my questions are, can i use the polyester gelcoat to pull epoxy parts? and can i use epoxy and glass fibre to reinforce the polyester mould? if i cant use epoxy glass fibre to reinforce the mould, can i use the polyester tooling gelcoat with glass fibre to reinforce it? thanks in advance
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Joe
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Hi, Yes, epoxy tooling gelcoat is always better for making epoxy parts. Many people will tell you that polyester will stick to epoxy. I use polyester filler to "prepare" the parts i will use to make epoxy molds with. I never had a problem with demolding a part. But, I use like 12 coats of wax, paying extra attention not to apply too thick coats so excess will remove easy. No PVA, but using it would prolly rise chances of success. So, in a way, polyester is not a way to fail each time. No, its not recommended, but no, I never had a problem. Maybe i was just lucky. The first carbon fiber / epoxy part I ever made was in a polyester mold. It was 30*30cm area on like 20 cm deep with some tight curves. So you see its not an easy-releasing flat panel. I had my carbon fiber part out of the mold by pulling it AND using some air pressure persuasion. Took me like 20 minutes to have it off the mold. The mold or part was not damaged during the process. Maybe it would have pop right off if I had used epoxy mold? Dunno. I made 2 or 3 parts like this and never had a locked part. But once again, I used 12 coats of wax. In short, if its your first attempt to make parts, i would buy compatible products. Just to have more chance to make your first project work "flawless". Nothing more disappointing than a first failed attempt  . i dont know about reinforcing a polyester mold with epoxy... i bet its not a good idea cos i never saw someone do it. Remind me a good tip I learned from trial and error: DONT USE EPOXY RESIN WITH GLASSFIBER MAT. For chemical reasons I could not explain, they dont mix together. Glassfiber CLOTH will work with epoxy, tho. Once again I would buy compatible products for the first try. You can still reuse the polyester stuff you have on later project. And if you like working with composites, believe me, it wont be lost. Hope it helped you. Cheers from Belgium
 A $1000 electronic device will always protect a 10 cents fuse
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japcarmaniac
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hi, thanks for the info. ive found out that i can use the polyester mould with epoxy parts as long as its waxed/pva properly but the mould may shrink or warp overtime. the rest of my supplies are on the way so hopefully ill get good results as ive been reading up on this for about a month but im still expecting some bump on the way as you would with anything you havent tried. here are a list of the supplies i have. if anybody can point out anything else that may come in handy feel free. polyester tooling gelcoat epoxy laminating resin pva mould release wax wooden spatulas for mixing sponge brushes for applying pva.i was going to use a preval sprayer scales colourclay carbon fibre cloth fibreglass cloth gloves paper cups
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Carbon Tuner
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Get some Acetone  And goold luck brother!
If Brute Force Isn''''t working your not using enough...
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japcarmaniac
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Carbon Tuner (22/01/2012)
Get some Acetone And goold luck brother! for wiping uncured resin?
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Gus Nimateck
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No matter of product you are using ,if your mold is treated to a mirror finish (3000grit) and waxed properly you don't have a problem. Personally I am using vinyl ester tooling gel coat and I never had a problem. It is time consuming and requires many hours of intense workmanship in order to achieve a mirror mold finish. I start by wet sanding the mold from 300grit up to 1200,and then I buff it to perfection.
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carboncactus
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You can pull epoxy off a polyester mould surface, but it must be depleted of its styrene content as much as possible. Otherwise the epoxy will make a chemical bond with the uncured ester groups.Easiest way is to post cure the mould to the HDT of the gelcoat, ramping it slowly. This will finalize the curing and you will be able to smell the styrene as you cook it.If you don't have access to an oven that can accommodate the mould, you can put concave side facing down in the warmest environment you can find for a couple of days, a week to be sure.
What I find weird is your choice to use epoxy to laminate while you use a polyester gelcoat.Normally you would laminate with epoxy if your gelcoat is epoxy.Don't get me wrong - it will work! The epoxy (as I mentioned before) will bond with your gelcoat, but it just seems silly to use a cheap gelcoat and back it up with relatively expensive laminating resin. Not to mention that you will have to use glass cloth instead of chopped strand, making your costs even higher. By the time you add it all up, the gelcoat will be like 10% of the total bill, when it should be the most expensive thing on the list. The normal layup uses the more expensive, harder resins on the mould surface and decrease in spec as the laminate carries on i.e. vinyl ester tooling gelcoat, vinyl ester skin coat, polyester tooling resin. You cannot however, have an epoxy gel coat and laminate with poly. There's a saying that says epoxy will stick to anything but nothing will stick to epoxy. In this case this is true.
Acetone is a must for cleaning brushes, rollers, scissors, hands. It's also good for getting some tack on a previously cured laminate so the next layer can bite into it.
As for the PVA, throw it in the bin. If you use release wax correctly, it will release fine. It also gives the mould a textured surface and you will lose definition in corners. The only use I can think for it is if you we're making something that isn't cosmetic like a water tank or something.
So if I were you, keep the poly gelcoat, back it up with a poly skin coat and laminate with a rapid tooling system like Unimould and CSM.Next to that, get some epoxy gelcoat to go with your epoxy laminating resin, or get some silica to turn a bit of that resin into gelcoat, then use that if you ever need to make hard wearing moulds.
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fgayford
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carboncactus (08/06/2013)
You can pull epoxy off a polyester mould surface, but it must be depleted of its styrene content as much as possible. Otherwise the epoxy will make a chemical bond with the uncured ester groups.Easiest way is to post cure the mould to the HDT of the gelcoat, ramping it slowly. This will finalize the curing and you will be able to smell the styrene as you cook it.If you don't have access to an oven that can accommodate the mould, you can put concave side facing down in the warmest environment you can find for a couple of days, a week to be sure.
What I find weird is your choice to use epoxy to laminate while you use a polyester gelcoat.Normally you would laminate with epoxy if your gelcoat is epoxy.Don't get me wrong - it will work! The epoxy (as I mentioned before) will bond with your gelcoat, but it just seems silly to use a cheap gelcoat and back it up with relatively expensive laminating resin. Not to mention that you will have to use glass cloth instead of chopped strand, making your costs even higher. By the time you add it all up, the gelcoat will be like 10% of the total bill, when it should be the most expensive thing on the list. The normal layup uses the more expensive, harder resins on the mould surface and decrease in spec as the laminate carries on i.e. vinyl ester tooling gelcoat, vinyl ester skin coat, polyester tooling resin. You cannot however, have an epoxy gel coat and laminate with poly. There's a saying that says epoxy will stick to anything but nothing will stick to epoxy. In this case this is true.
Acetone is a must for cleaning brushes, rollers, scissors, hands. It's also good for getting some tack on a previously cured laminate so the next layer can bite into it.
As for the PVA, throw it in the bin. If you use release wax correctly, it will release fine. It also gives the mould a textured surface and you will lose definition in corners. The only use I can think for it is if you we're making something that isn't cosmetic like a water tank or something.
So if I were you, keep the poly gelcoat, back it up with a poly skin coat and laminate with a rapid tooling system like Unimould and CSM.Next to that, get some epoxy gelcoat to go with your epoxy laminating resin, or get some silica to turn a bit of that resin into gelcoat, then use that if you ever need to make hard wearing moulds. Often people will use a polyester gelcoat because it will buff up to a far superior shine than epoxy and it will last for many part as epoxy will not. Some will use the polyester gelcoat and a few layer of glass fiber and then sprinkle on a layer of chopped glass fibers into the wet surface. Let it cure and now you can use epoxy and glass right over the polyester and it will bond perfectly because the glass fibers become the coupling media. The reason you would go this way is for the superior shine of the polyester gelcoat and the stability of the epoxy. (no shrink and no distortion.) Do yourself a favor and forget about the wax and get the EZ Lease release agent. You will never ever go back once you have tried it. Hope this helps. Fred
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fiberglasshawaii
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Just some vinegar to break down the epoxy so you can re-use the brushes and like Carbon Tuner said, acetone.
Fiberglass Hawaii Inc.Oahu - Maui - Ventura http://shop.fiberglasshawaii.com
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