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Apprentice

Registered: 02-2004
Posts: 297
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Re: Bioweapons.com and Urethane


Don’t tease us with all the info can you detail on some of the fine points :wink

Does agitation affect the properties of plaster?
Ask yourself why all your plaster molds are so heavy and for what purpose?
Is the burlap really reinforcing the plaster, or just in the middle surrounded by plaster?
Are you weighing out your water/plaster ratio, or "eyeballing" the mixture?

I think most guys are eyeing depending on what layer they are doing. Tradition is of course burlap and just thick enough in total to hold up to being moved around and not break easy. Can you share some fine steps and tech. and the reasons please?


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Dont disrespect the archetype with the pathetic sides of the human condition


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Caped Crusader

Registered: 02-2004
Posts: 1182
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Re: Bioweapons.com and Urethane


Yeah, plaster. Good stuff. I use Hyrdocal B-11 all the time. Underrated I think also.

1. U.S. gypsum has a chart on their website that has all the weighed measurements. Weight this stuff. Let's think about the eyeballing method for a minute. Consistency? Probaly none. Some pieces will be better than others, some like chalk.

2. Reinforcement. It takes lots of plaster to work its way through twoven burlap. If the reinforcement material is dry, you get a sort of hydroplane effect. i.e. if the reinforcement material is soaked in water first, then the plaster will work its way through each fiber more quickly and evenly. You want that. Otherwise you can get internal dry spots.

I prefer thin sisal chopped to about 2 inch lengths (use a paper cutter). Makes it easier to maintain even mixture of plaster and sisal. Throw the wet sisal right in the bucket and mix it up good.

This will make it easy to keep your coat under 1/2" thick. I never make my mold more than 1/2" thick, ever. If those sisal fibers a too long, you will have a hard time insuring an even coat. Too short, and the reinforcement qualities will be lessened.

So you have a beauty coat of water/plaster weighed out, and a reinforcement coat weighed out in 5 gal containers. That's all you need. If you make this stuff too thick, it's not only heavy but more prone to warpage and expansion due to the heat generated by the crosslinking of molocules.
   
If I made up a bucket of plaster or urethane and kept it in the bucket, it will go off much faster (and gen more heat) than if I pored it out in a thin layer after mixing. i.e. the crosslinking has been slowed down considerably.

3. Mixing. You want at least 5 times the volume of bucket than plaster. i.e. for mixing 1 gallon of water/plaster you want to mix it in a 5 gallon container. With a lid and a hole for the mixing blade to go through.

You get where I'm heading with this. I'm guaranteeing that you will not whip plaster all over yourself and the room. You want a hand drill that will shear this stuff as fast as possible. Thorough mixing and agitation is key.

4. Application. If you apply a reinforcement coat after the beauty coat looses it's shine, you're screwed. De-lamination will eventually occur. Start applying the second coat while the first coat still looks wet. You are getting a good CHEMICAL BOND.

Don't worry about print-through so much. This is why you will have ALL the coats of plaster weighed out in advance, so you can move like a bat outta hell when doing large pieces. You aint got time to mess with that when in the heat of battle. Good preparation is key.

5. Finishing. As the final coat (I usually only use 2) is setting up, groom the surface. Hand grooming surfaces is something that we all do in SPFX, be it clay plaster, etc... Make it look nice.

Also before the final coat goes dry, have some PVC pipe on hand to add FEET. You can then pop nice rubber tips on the feet. Handles if necc. A mold without FEET makes me want to pick the damn thing up and throw it accross the room, cause I will have to come up with a silly way of keeping it in position while I use it.

If this is for pouring a slip latex skin I would incorporate spindles on each side of the head mold so I can easily pour out the latex without having to pick up the mold to empty it out. The mold is suspended, lift up the bottom or incorporate a handle, and let it pour out. Now leave it drain upside down and the next day you will have a nice EVEN skin.

But you have to have enough latex to fill the mold up front. An even skin will make the latex skin look better, keep its original shape better, and be more effective time/money wise. Brushing in layers at a time is too much work for my old bones. Can't guarentee an even skin.

6. Some other topics - Nice clean dividing walls. Keys. How would you make a one piece cowl mold when an armature is involved?
 
7. Overall, plaster does not have the strength, stability, durability, flexability of say epoxy, but unless you really need epoxy (a car?) why go into the expense? Remember it's cheap (I pay $28.00 for a 100 pound bag). I did a full body suit 2 yrs ago (slip latex) in two halves front and back and could easily carry each half.

I like to bake out my plaster in an oven at a low temp (100 deg) before using for anything. Get all the wetness out. Just like you would for foam latex.
    
Hope I covered everything, if not, gimme a holler.

Last edited by Deadly Lemur, 3/25/2006, 3:19 pm
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Apprentice

Registered: 02-2004
Posts: 297
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Re: Bioweapons.com and Urethane


Love it ! Love it! Love it!

I also prefer HC to epoxy still. I use a pretty close method to yours but still eyeball because the ratio on the tech sheets seems to make the mixture a little watery. I will refine my weights to custom from trials and get a little more accurate.

Can you just clarify the steps of coats you lost me on how many total, and when do you add the burlap. I got 1st beauty, 2nd reinforcement, than was it 2 application coats? And your 2-inch strips are added almost like filler in bunches and not applied one at a time, I always thought the doughnut method was the best.

I like to use a urethane foam core for my cored masks. Than flip that baby around and burn out the core with a torch and instant one piece mold no seams. That’s if I'm not going to mold the piece in silicone first so that I can pop a urethane master (lasts longer) and than mold that in stone. After that make my latex/urethane foam masters to pop future copies in stone from.

BIG BIG thanks; love the flow of info really makes a difference!


---
Dont disrespect the archetype with the pathetic sides of the human condition


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Caped Crusader

Registered: 02-2004
Posts: 1182
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Re: Bioweapons.com and Urethane


Yup, you got the standard method for one piece Halloween masks, urethane foam armature, burn it out, peel away the walls of clay.

For you beginners out there, when you torch an armature such as a styrofoam head, make sure you do it OUTDOORS, AND wear a respirator. The fumes from burning urethane and or styrofoam are REAL bad. If I'm not mistaken the fumes from melting styrofoam contain cyanide gas.

On the reinforcement thing, I just use two coats, initial coat, and reinforement coat, then start smoothing out the surface. I like to try to make these pieces as light and as thin as I can get away with. Some extra bulk will be in the adding of leggs/handles.

I do really like the chopped sisal (2 inch length). Stick it all under water first to break the dry tension, it will suck up the plaster quicker. Time ain't one thing you got a lot of with this. But if you get to know this stuff through experience, it's nice cause you learn to get over quick.

Get a lid for that 5 gal pail, punch a hole in it for your mixing blade, pop the lid on tight, and shear away like a mad man. Nothing is gonna spray out.

Also DO NOT rinse out buckets of wet plaster in the sink unless you love to screw up the plumbing in your workshop/house. Pour it out into the garbage. Many other issues I have not covered, so bring up if you got em'. Bob out.

Last edited by Deadly Lemur, 3/25/2006, 3:21 pm
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Apprentice

Registered: 02-2004
Posts: 297
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Re: Bioweapons.com and Urethane


Good stuff Bob. I got a pretty good method going but I think with a couple of your tips it will be even better. Thanks again.

---
Dont disrespect the archetype with the pathetic sides of the human condition


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Caped Crusader

Registered: 02-2004
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Re: Bioweapons.com and Urethane


One thing I would like to add. About 10 years ago this material became the rage, and I don't know why it sorta died out. --- Epoxical. It's a beauty coat meant to be backed up with standard ultracal. Awsome stuff, tough as nails, and you will get a zillion good pulls from making slip latex masks, as its water absorbant. More expesive than standard ultracal, but the intention is for it to be used as a thin 1st coat. All the standard tech. apply.
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Apprentice

Registered: 02-2004
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Re: Bioweapons.com and Urethane


Bob does that stuff have some of the same problems as using acryl-60. Does it bite a little to hard into clear coats and such. Does it release as easy as UC. How well does the UC adhere to it will it delaminate.

---
Dont disrespect the archetype with the pathetic sides of the human condition


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Caped Crusader

Registered: 02-2004
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Re: Bioweapons.com and Urethane


No, will not de-laminate. Made for use with ultracal. I was at Gil Mosko's shop 10 yrs. ago, he was showing molds he had made with it. No negatives that I know of. Stuff was resistant to chems from foam latex, which as you know foam latex attacks the surface of just about anything. No ph problems. You're talking about the finish coat (kryolan, plastic cap?) from a sculpture becoming fused with the inside of the mold? easy fix. Get a pump sprayer (empty windex sprayer) add water with a few drops of dish soap. Now spray it on the clay, let completely dry. Ya, if that happens it can block up the water absorbtion ability of the mold.
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Apprentice

Registered: 02-2004
Posts: 297
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Re: Bioweapons.com and Urethane


Bob are you saying to spritz the soap/water on instead of using the kryolan? Wont the UC reactivate the soap? I usually use CC than come behind with removable dulling spray because its a water base. I had problems with just CC before. Also what do you suggest for a sealer if you need to cast a WED sculpt in fiberglass? Do you go with parfilm or pva for better detail?

---
Dont disrespect the archetype with the pathetic sides of the human condition


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Caped Crusader

Registered: 02-2004
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Re: Bioweapons.com and Urethane


Sorry it took so long to get back on this.
The ultimate would be green PVA (poly vinyl Alchohol), but for most people in home shops it might not be realistic, as you should have good ventilation/respirator.

If you put just drops into a spritzer the size of a windex sprayer, and completly let it dry you will be fine. But if you had too much soap on the surface, then you might end up with the inside of the mold being junk.

Likewise, I am not a big fan of the body cast method where a guy gets into a spandex jump suit, then they grease him down to the max with vaseline, The vaseline gets sometimes mixed in with the beauty coat. Vaseline is just awful. Ever try to wash vaseline off your skin/hair? Yuk! Can be absorbed by plaster as well.

I think that if you do a sort of DE type cowl that is close to the skin, you can make a really cool cowl doing just the basic methods. I hear a lot people say that if they use this material or that material it will make a better piece. Not neccesarily, so says I.

I say it's all about the artist and what goes on inside your head. You need to have a clear clear vision of what you want end result of your costume to be, how it will move/look etc... When making latex skin suits/costume parts I like organic texture rather than a machined look, as it translates better on skin latex IMHO.
     
If I were to hire someone for a film, or important project, I would rather hire a guy who knows maybe 2-3 materials like mad, rather than someone who has a bit of experience with 10-20 materials, because the guy with killer knowledge/experience with plaster is gona give me fast, topnotch, consistent results. He knows this stuff like a sixth sense. He knows exactly how thick a latex skin will be based on the brand/type of latex, the mold, the humidity and temp, and time it sits in the mold. He doesn't have to guess much. cause he's done THAT specific thing so damn many times it's a walk in the park.

Last edited by Deadly Lemur, 3/25/2006, 3:24 pm
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