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Unread 12-04-2012, 12:46 AM   #1
FRONTLINE
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Question ???casting resin (like smooth-on)/paper mache clay/rid fiberglass fumes???

I want to build something similar to this: http://machine56.deviantart.com/gallery/#/d29rnw0

Casting resin:
1.What is the cheapest brand without sacrificing strength or detail? I don't want to spend so much on just one helmet if I don't have to. Also, which one would be the easiest to use? What makes casting resins difficult in the first place?
2.How thick does it have to be to be strong? I never could find out how thick everyone makes their castings
3.Can you use silicon caulk for a replacement/cheaper alternative to a rubber mold? What about plaster of paris?
4.Does any of the brands give off fumes/an odor before/after they cure?
5.Which one is good at being sanded/drilled/cut with a dremel?

Paper mache clay:
1.Has anyone ever tried this? (If you scroll down you can see my posts with the same picture from above) Any suggestions on this or paper mache period?

Fiberglass fumes:
1. I've heard that even after it's cured that it gives off strong fumes. Is there any way to avoid/remedy that?
2.Can you seal the fumes using primer spray?
3.Are the fumes harmful?
4.Can you wash the fiberglass piece to get rid of the smell?


***As a side note, is it cheaper to do fiberglass than using casting resin?
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Unread 12-04-2012, 03:44 AM   #2
rj_sosongco
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Quote:
Originally Posted by FRONTLINE View Post
I want to build something similar to this: http://machine56.deviantart.com/gallery/#/d29rnw0

Casting resin:
1.What is the cheapest brand without sacrificing strength or detail? I don't want to spend so much on just one helmet if I don't have to. Also, which one would be the easiest to use? What makes casting resins difficult in the first place?
2.How thick does it have to be to be strong? I never could find out how thick everyone makes their castings
3.Can you use silicon caulk for a replacement/cheaper alternative to a rubber mold? What about plaster of paris?
4.Does any of the brands give off fumes/an odor before/after they cure?
5.Which one is good at being sanded/drilled/cut with a dremel?

Paper mache clay:
1.Has anyone ever tried this? (If you scroll down you can see my posts with the same picture from above) Any suggestions on this or paper mache period?

Fiberglass fumes:
1. I've heard that even after it's cured that it gives off strong fumes. Is there any way to avoid/remedy that?
2.Can you seal the fumes using primer spray?
3.Are the fumes harmful?
4.Can you wash the fiberglass piece to get rid of the smell?


***As a side note, is it cheaper to do fiberglass than using casting resin?
I can answer a bit of these questions:

1. I don't know what the specific different brands are for resin, but I can tell you that the process won't be cheap, at least not initially. You need the materials to 1) sculpt a master, 2) make a mold, and 3) cast the resin copy. Look for tutorials on resin casting here as well as on places like the 405th and RPF, and you can probably find the different kinds of resin, and different experiences people have had with it. Once you have the basics, it becomes cheaper. If you use an oil based clay to sculpt, you can reuse it after creating the mold. Also, if you only plan on casting multiples of the same prop, your future costs are just the final casting material.
2. From what I can tell, resin doesn't need to be super thick to be solid. I ordered a resin cast of a Green Ranger helmet off Rangerboard, and it's generally 1/4 to a 1/2" thick at the most. You can always lay some more fiberglass inside to reinforce it.
3. Generally when casting something, what I've seen is "one part is soft and the the other part is hard." What this means is that if you want a soft prop (like a latex mask or prosthetic) the mold is hard. Vice versa, if you want a hard solid prop, you use a soft material for the mold, plus a hard outer mold to keep the shape. The idea is that you can work the softer part away from the hard part without damaging either. Plaster might be good for an outer mold around a silicone base, but if you try to cast something hard in a plaster mold and don't take the proper care to de-mold, you can damage both the prop and the plaster.
4. As the curing process is a chemical reaction, most casting materials have some kind of odor. There are a few low or no-odor materials, but I don't know them specifically.
5. Resin is essentially a plastic, so it can usually be worked with your standard power tools. A dremel should be fine.

1. Paper mache clay is a cheaper, simpler method. You can either buy the pulp and add water, or you can buy the premixed paper clay. Either way, it's easy to sculpt, no fumes, dries hard, is workable/sandable with most tools, and is strong and lightweight. However, it is prone to shrinking, since the drying process involves the water evaporating. Also, it needs to be reinforced. It's strong as an outer coating, but brittle unless it's sufficiently thick.

1. The only way to remove fumes is to let the prop stay outside for an extended period of time. Fresh air and time will allow the prop to fully cure and for the fumes to dissipate. You're dealing with a chemical reaction, so there's going to be some residual chemical fume for quite some time. You don't want to wear a resin mask the day after it cures, or you can seriously injure yourself.
2. Primer spray won't necessarily mask the fumes entirely. It might actually make it worse, as now the prop smells of both resin AND the spraypaint. Furthermore, the resin fumes might become trapped, taking longer to dissipate. Best to give each stage plenty of time to fully cure and air out.
3. Again, this is a chemical reaction in the curing process, so yes, the fumes are harmful. ALWAYS use in a well ventilated area, with a proper ventilator mask, eye protection, etc. The same goes when sanding, especially if you're sanding things like paint or bondo body filler; the microscopic particles can get into your lungs and cause all kinds of problems, from chemical poisoning to breathing problems to even cancer.
4. You can wash the fiberglass once it fully cures. I don't know if it will get rid of the smell entirely, but it's worth a shot.

To answer your question about fiberglass cost: Yes, in a sense, it is cheaper to do fiberglass. However, not many people actually build with just fiberglass. Most of the time fiberglass is used to reinforce an existing structure, like a pepakura (papercraft) prop or armor. The process is similar to paper mache: coat the object in fiberglass resin, lay some fiberglass mat or cloth down to build it up, and seal with more resin. Depending on how you build the initial structure, fiberglassing can keep your costs down or they can just add to it.

As a side note, resin casting usually only serves 1 of 2 purposes: either a) you really REALLY want a lightweight, plastic, resin prop or costume, or b) you want to cast multiple copies of the prop. The process is tedious with the 3 stages (sculpt, mold, cast) and takes a lot of time. Think about how you want to use the mold if you decide to make it. If it's a one-off, it may be better to just make the prop outright than try to make a master, mold it, and cast it. There's a saying in retail:

Quality
Price
Speed
Pick two.

Similar can be said of cosplay construction. To get the best quality, you need to be putting in the investment for the best materials, or you put in the time required to properly use those materials. The cheapest methods usually require more time to get them to the same level of quality. And the fastest methods usually suffer from rushed quality , or they require a bigger money investment to speed up the process (quick-setting resins, etc).
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Unread 12-04-2012, 01:00 PM   #3
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rj_sosongco speaks the truth. Adding to what he said:

3: I haven't used silicone caulk as a mold personally, but as long as you let it cure, it should work fine for all casting resins. The mold must be strong enough to not wobble or deform. If there is a chance of this happening, you want to make a rigid mother mold.

You can use a rigid mold (such as plaster of paris) for casting a rigid piece if the piece has no undercuts. An undercut is a feature that once cast would cause the rigid piece to lock tight into the mold. Undercuts are safe when either the casting or the mold is flexible (within reason) because it'll just peel out. Another way to get around undercuts is to design a multi-piece mold. However, the more pieces in your mold, the more complicated it becomes, the more places for you to screw up, and the more seam-lines that need to be trimmed away.

If you make a plaster mold, make sure to use a release agent. I like to use a commercial mold release, but you can use PAM cooking spray in a pinch. Give it a minute to dry/soak in and then dab up any excess.

4. Polyester resins all have fumes. Epoxy has fumes, but they are less noxious, and they are less detectable after the piece has cured. Polyurethane resin has almost no odor, though it should still be used in a ventilated area.

Paper mache clay:
Paper mache clay should really only be used to repair flaws or add complicated details. The base should be paper mache. If you do paper mache carefully and with the right paper, it can be nice and strong. Waiting for it to dry is the only really annoying bit.

Fumes:
1. You can speed the flashing off of the fumes by building an oven box. This is basically a cardboard box lined with aluminum foil with an incandescent bulb or sun-lamp in place. poke one hole in the bottom of the box and one hole in the top to allow just enough airflow. Then let it sit in there for a couple days. You have to design this properly or it is a fire hazard. Barring that, yeah, outside in the sun for a few days.

2. When the fumes are almost gone, yes, a coat of Killz paint helps mask the odor.
3. Just how harmful these fumes are is under debate. This is partially because it is hard to scientifically prove something like that one way or the other. After the piece has had a few days to cure, it is generally considered that wearing a resin mask a few days a year won't seriously harm you. If you feel dizzy or anything, don't be a hero; take a break.
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Unread 12-05-2012, 08:42 AM   #4
underdog1425
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I've had luck using floral foam and just carving then covering it, effectively combining the scultping and mold steps. If you want you can even dissolve the foam with acetone afterwards.
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