Fiberglassing V Resin Slush Cast?

I will soon be making Blade Runner VK machines with the molds I purchased from TH Studio

Having never done hollow casts before, I'm currently weighing up the pros and cons of fiberglassing v slush casting for the main unit.

I've read that fiber glassing is pretty tricky to get right, and rquires lots of practice.

Slush casting would seem to require a lot of time and resin wasteage to build up suficient wall thickness.

I would appreciate anyone who can weigh in with opinions, tips, tricks or links to (preferably illustrated) tutorials.

So how would you go about it?

Anybody??

If you have no fiberglassing experience I would probably start with slush casting...

Birdie said:

I've read that fiber glassing is pretty tricky to get right, and rquires lots of practice. ?

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No, actually it's really easy...provided you use epoxy resin.

See, what people usually refer to as 'fiberglass' is actually glass fiber cloth or roving impregnated with resin. Industrially, this resin is either epoxy resin or polyester resin.

Epoxy is very strong, doesn't require any gel coat or multiple layers, and doesn't outgas nasty fumes or attack your hands with nasty chemicals. Once mixed, the resin is sticky and messy but isn't the toxic stinky problem polyester is.

Besides being messy, you can only make one casting about every day (it takes about 10 hours to harden to 'green' hardness). On the other hand, It's way stronger than urathane or polyester resin (which I won't use, it's got too many issues).

You can use fiber glass cloth with urathane resin, but you have to be prepared and work fast. Basically, you have to mix chopped fiber with the resin and then pour it fast before it turns to rock in the pot. Another way is to pour a thin layer of urathane into the mold to take detail, then lay the cloth in and add more urathane.

Maybe the solution that is best for this is to use epoxy fiberglass for the big parts that are structural and just cast solid the smaller parts out of urathane. I assume that you want hollow castings so as to stuff them with electronics, yes?

If you want more info, you can e-mail me simon: I've used fiberglass on a lot of projects, as it is more practical and cost effective when you're making 'one off' projects.

http://www.youtube.com/watch?v=30sN5NLa7Ic

Heres my short tutorial on fiberglassing a helmet

I assume that you want hollow castings so as to stuff them with electronics, yes?

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That's the plan

Birdie said:

That's the plan

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Well, you got my e mail old buddy. I'll be happy to give you any help I can.
The biggest issue for you will be 'where to get materials' I think....
they probably don't have the same brand names in the UK I use.

Epoxy is very strong, doesn't require any gel coat or multiple layers, and doesn't outgas nasty fumes or attack your hands with nasty chemicals. Once mixed, the resin is sticky and messy but isn't the toxic stinky problem polyester is.

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What kind of glass fiber cloth works best with epoxy resin?

Birdie said:

What kind of glass fiber cloth works best with epoxy resin?

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Well, actually it's more about the project itself. Any sort of glassing cloth will work, but it's more about what type best suits what you're doing.

Typically, it comes as woven cloth of various weights and fineness of weave or batting.

If you use the cloth type, it's usually better to use a lightweight, fine weave cloth for smaller project, because obviously when you are laying cloth in the mould it's easier to get finer cloth to conform to the inside. You don't want the cloth to wrinkle too much because it creates air pockets, and you want the cloth to laminate with the resin. Finer cloth also soaks up the resin better.

There's also batting, which is short strands (about an inch or so) that aren't woven, just kind of pressed together in a sheet. That's what the previous poster Tim Allen was using in his video. If you're doing curved or complicated shapes this usually works better, because it won't wrinkle or fold and you can tear out pieces that suit the area you're working on.

The nice thing about batting is you don't have to cut it to shape like cloth: you can just rip irregular pieces out with your fingers. It's not as strong or smooth as cloth though... so the inside of the piece (not in contact with the mold) will be rougher looking.

Also, if you can get it I recommend using carbon fiber or nylon glassing cloth. See, glass cloth is literally that: tiny thin strands of actual glass! You have to wear gloves while handling it, because it is constantly emitting tiny sharp shards of glass...especially when you cut it. Obviously, this is terribly irritating to your skin. Be very careful to ONLY wash your hands with cold water after doing fiberglass work: if you use hot water the tiny shards get into your pores and REALLY itch! ALWAYS WEAR GLOVES WHEN HANDLING CLOTH OR BATTING! When sanding or cutting the flash off the finished piece wear a dust mask for the same reason.

Nylon and carbon don't have this issue...and they are stronger. With small projects, it's worth the extra cost.

Have you got a source for materials in your area in mind?

Using carbon fiber, nylon glass cloth or even epoxy would be pretty wasteful for a VK machine. Those type of material are generally used for specific issues in a part or piece. Yes it's better, but do you really need that?

Realistically you are building a prop. Stick with regular every day polyester resin and 4-6 oz. matte fiberlass, plus an average sandable gel coat (1630).

micdavis said:

Using carbon fiber, nylon glass cloth or even epoxy would be pretty wasteful for a VK machine. Those type of material are generally used for specific issues in a part or piece. Yes it's better, but do you really need that?

Realistically you are building a prop. Stick with regular every day polyester resin and 4-6 oz. matte fiberlass, plus an average sandable gel coat (1630).

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Yeah, it would work, but I wouldn't recommend that to a beginner. Epoxy is just plain easier to use, and less dangerous. It costs the same , and is stronger....so the only advantage of using polyester is that if you put a lot of catylist in it, it will set up faster.

I don't think birdie has somebody there to show him the proper mixing and use of the gel coat layer, or how to lay the various layers necessary for polyester. These chemicals can be dangerous to use if there's no one there showing you the ropes, and polyester is just a lot more messy and toxic than epoxy. Both the unmixed chemicals and the catalysed mixture can give you skin burns and allergic reactions, not to mention the toxic fumes.

Birdie said:

What kind of glass fiber cloth works best with epoxy resin?

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You need to verify with the manufacture as many chopped strand mats have a binding agent (glue that holds the strands together) epoxy resins won't dissolve this binder, causing issues and improper wet out... Don't just assume it will work without confirmation from the manufacture that the mat is epoxy friendly, many are not...

Epoxy is just plain easier to use, and less dangerous. It costs the same , and is stronger...

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Epoxy is generally about 2-3 times the cost, true on the rest...

exoray said:

You need to verify with the manufacture as many chopped strand mats have a binding agent (glue that holds the strands together) epoxy resins won't dissolve this binder, causing issues and improper wet out... Don't just assume it will work without confirmation from the manufacture that the mat is epoxy friendly, many are not...



Epoxy is generally about 2-3 times the cost, true on the rest...

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Not if you're doing something small. Typically, and this is where I get it, Casting epoxy is about $30 a half gallon...whereas you pay about 20 for a half gallon of polyester. But then you have to buy gelcoat, curing agent...
after that the cost is the same.

If he was doing 10 suits of armor it would make sense to want to save some cost on materials...but in this case the cost of materials isn't the issue: most of the cost of a prop is labor, not materials.

Most people here tend to cast things out of urathane in rubber molds...which is VERY expensive. However, it is well understood and predictable, so people just figure the high cost of the method as unavoidable because you save so much time and work when making multiple copies.

In this case, I recommend this for simon because it's workable, inexpensive (comparatively) and more fail safe than using polyester or some of the more exotic materials.
If he wants a faster cycle time then I'd suggest using urathane resin with fiberglass, as I outlined earlier.

Ham Salad said:

Not if you're doing something small. Typically, and this is where I get it, Casting epoxy is about $30 a half gallon...whereas you pay about 20 for a half gallon of polyester. But then you have to buy gelcoat, curing agent...
after that the cost is the same.

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You need a catalist with epoxy resins as well and just like polyester it is or isn't included in the package... I have never not had the catalist included with polyester resins, unless I mail ordered due to it's hazardous status, but then even most of the time they sneak it in...

As for the gelcoat/suface coat just because you are using epoxy doesn't mean you should leave it out, it has a purpose that being to provide a smooth surface void of any fabric or mat imprint pattern... Gelcoat/surface coats are regularly and almost always used in any layup where you want a nice initial finish...

Most people here tend to cast things out of urathane in rubber molds...which is VERY expensive. However, it is well understood and predictable, so people just figure the high cost of the method as unavoidable because you save so much time and work when making multiple copies.

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Time is money... As for the rubber mold you need a similar mold for whatever kind of casting you are doing, no money saved there in any scenario...

As for the cost of urethane resins, they are no more costly then epoxy... But turn around time is about 20 minutes from start to finish...

I am thinking of going with this place: http://www.cfsnet.co.uk/

They do a cheap epoxy starter pack that I can use to get some practice with and some grip on what I'm looking at

Seem to have a pretty thorough range of products too. I usually use smooth-on for urethane.

Birdie said:

I am thinking of going with this place: http://www.cfsnet.co.uk/

They do a cheap epoxy starter pack that I can use to get some practice with and some grip on what I'm looking at

Seem to have a pretty thorough range of products too. I usually use smooth-on for urethane.

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It appears they sell "West System" resin it's very popular and good quality...

Don't be shy to try a slush casting with urethane, rather then jump into glassing right off the bat...

Birdie said:

I am thinking of going with this place: http://www.cfsnet.co.uk/

They do a cheap epoxy starter pack that I can use to get some practice with and some grip on what I'm looking at

Seem to have a pretty thorough range of products too. I usually use smooth-on for urethane.

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I use smooth on too, but they have several formulations....do you use their grey stuff, their blue stuff or their green stuff?


Sorry I don't remember the product numbers....

Made sure you get plenty of Mold release: I use PVA, it's good for urathane too and cuts down on mold wear as well.

I looked at that web site...if I'm reading that right, boy is that expensive!

Though I am not an artist, but had unpleasant experience with fiberglass material from canoeing boats.

What I heard is to coat your hands and arms with tacum or baby body powder before handling fiberglass to prevent glass particles getting into the pores of the skin. And just put your hand under running water without rubbing, to rinse off the glass dust.

exoray said:

You need a catalist with epoxy resins as well and just like polyester it is or isn't included in the package...

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Well, where I get it is: it's a 50/50 pack, you get 1 quart of resin and one quart of catylist which makes a half gallon of casting epoxy. That will run you 30 bucks or so. It's transparent, you can make pretty good clear castings with it, but it isn't 'water clear'...distortions in it.

exoray said:

As for the gelcoat/suface coat just because you are using epoxy doesn't mean you should leave it out,

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Casting epoxy doesn't use a gelcoat. They do not even sell it, at least where I get it. It comes out glass smooth from the mold. All I do is brush it into the mold, wait an hour, and then lay the mat in and add more epoxy. I suppose what you mean is that gelcoat for epoxy is just....more epoxy.

exoray said:

Time is money... As for the rubber mold you need a similar mold for whatever kind of casting you are doing,

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Nope. You can cast epoxy into a stone mold, no rubber necessary.

That's why it's really good for doing 'one offs': casting epoxy passes through a 'green' stage, it is solid but not hard yet, so you can yank it out of hard molds without destroying the mold.

You can get about 4-5 pulls out of a stone mold, depending on the level of detail. I made my briarios suit that way, the arms and legs were just stone molds, and they were fine after 2 pulls each (that was enough for one suit).

So all the molds (which were huge) cost about $30 in dental stone, plus I used about 2 gallons of epoxy, so the total price for the unfinished arms and legs was about $160 or so.

mind you, if you wanted to do something really details with lots of nerny, you'd have to make the detail sections seperately... The really fine undercut detail would get broken out of the mold after the first pull.

On the other hand, if you only need ONE, that doesn't matter. Since I don't tend to sell stuff, and don't have anyone locally to make for, usually I only need one or two of something. If I need a bunch I use rubber.

exoray said:

Y
As for the cost of urethane resins, they are no more costly then epoxy... But turn around time is about 20 minutes from start to finish...

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And nope again: the casting epoxy I have been getting takes about 8 hours to get 'green' hard...that is solid but a bit rubbery. It taked a full 24 hours to reach rock hard. I've never seen an epoxy resin that cures so fast....where do you get that?

Just curious, can JB weld or ardelite resin epoxy be use as well?