26.0 - Making your own appliances
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Courtesy of Tashta, steps on making your own appliance - http://www.stripedsmiles.com/TheMask.html
Casting Positive Forms in Latex and Urethane, by Christopher Pardell - http://users.lmi.net/~drewid/latex_faq.html
Moldmaking and Casting FAQ - http://www.ravensforgeminiatures.com/faq20413.html
Sources for maskmaking/special effects - See section 99.9 .
Sources for moldmaking/sculpting - See section 99.10 .
26.1 - Lifecast sculpting
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Sculpting clay -Roma Plastilina - a "sulfur" clay
The word plasticine should be avoided - it is used to refer to both clay and plastic explosive.
26.2 - Making positive and negative molds
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From: YSENGRIN (Verdun Manor)
Sub: Moldmaking
(Excuse how badly this may ramble - I've been up for two days and I'm putting this up just before I go 'way and crash)
You're making a pretty large mold for a horse's head. If you're planning on filling it with latex, letting it sit for a bit, and pouring it back out (repeating the process to make it thicker), the insulation foam will not work - that much latex is HEAVY! The insulation foam will also not pick up the surface detail very well, and it may retard the setting of the latex. The foam will also force its way through a layer of Vaseline to adhere to whatever's under it - as we found out by trying to use it to make a positive from a plaster mold.
Just as a suggestion - don't skimp on putting skin textures on the head. It's not much trouble and it does add quite a bit to it, even if you're planning on furring the face. You might want to use the mold for a furless skin someday. (I've got one wolf head that looks great with fur - but I can't do anything else with it 'cause the sculpture was smooth as a baby's bottom). Sculpting wrinkles is easy with a piece of saran wrap and modelling tools.
Look at the sculpture to see how it naturally wants to divide into mold pieces. On our werewolves we usually split 'em across the top of the head and through the ears, so that the muzzle has no mold lines, but a horse's muzzle is much larger and it may not work for you. Consider taking the ears off and casting them separately - it makes the mold a lot smaller and easier to handle. As you're casting with flexible latex, and not using foam latex, undercuts shouldn't be a problem - just note where they might occur so you can make certain that the latex gets into those areas when you're casting.
Use playing cards or flexible metal palettes to divide the sculpture as the mold sections will go - you're basically building a dam. Make the dam at least two inches (5.1 cm) high. You can use clay to build the dam - I just personally don't. Make certain that there's no sharp angles in the dam that might cause the mold to lock up. Cut spheres of clay into halves and place them on the dam to make indentions in the first part of the mold you're going to make - these will act as alignment keys. Again, try not to place them such that the mold will lock up when you try to separate the halves (or thirds, or whatever. You should be able to do the head with a two-piece mold). Support the sculpture so that the first part of the mold you're going to do is as flat (horizontal) as possible - it makes it much easier.
Get two or three large mixing bowls or buckets (plastic is good 'cause you can flex the dried ultracal out) and a bucket of clean water. You don't want to wash the ultracal off in the sink because it'll set down in the drains somewhere - wash off in the bucket. You can empty the water out of the bucket after the ultracal sets in the bottom of it. You may want to use rubber gloves; I don't like 'em, but the ultracal is rough on your skin.
(as a side comment, if you have enough room in the head sculpture, you might consider using a bicycle helmet to support the horse's head on yours. We use fiberglass skullcaps because we don't have the room, and they're uncomfortable after a while)
We use Ultracal 30 for moldmaking - it's reasonably cheap and has good thermal stability for cooking foam latex, and lasts reasonably well. Seal the sculpture - especially since you're using a taxidermy form - with clear acrylic spray. It makes it easier to clean the mold out later. Mix a small amount of Ultracal to the consistency of buttermilk and apply it with a soft brush on just the section of the sculpture under the first part of the mold. Be careful not to scar the skin texture - you're trying to apply a coat without air bubbles. Don't make the mixture too watery or you'll lose skin detail *AND* the mold will only last for two or three skins. Wait for the ultracal to lose it's glossy look (it turns matte) and repeat with a second coat. Both of these coats will be fairly thin. Wait for the second coat to go matte.
Now mix ultracal so that it's more the consistency of whipped creme. Lather it on with your hands, being careful not to crack the first layers by pressing too hard. You'll have the extra problem of the taxidermy form soaking up moisture and losing strength, too, so you should try to get the mold built up to strength as quickly as you can. Using the 'whipped creme,' build the mold up until it's roughly half an inch (1.3 cm) thick - for me, that's two or three more coats. Let the ultracal dry to matte finish between each layer; smooth the last layer with a wet sponge or your hands so that there are no large irregularities - something like a rough plaster wall is fine.
Now take burlap (or terrycloth) and cut it into strips about 2" (5.1 cm) wide. Wet a strip completely in the bucket of water, wring it out, and then saturate the strip in more of the whipped creme ultracal. Place the strip over the mold. Repeat, putting overlapping strips at right angles to each other. Smooth them down and use the rest of that batch of Ultracal to cover them. You should have roughly three layers of burlap, then the rest of the ultracal. Smooth the surface again. Wait for it to go matte (by this time it should be thick enough that you can feel it getting warm and perhaps even steaming). Don't be surprised if you get a few trickles of water from the mold at this point. Add an ultracal layer so that there's at least a quarter inch (0.635 cm) over the burlap. Then do the whole burlap thing over again - this is a large mold and it'll need the support. Smooth the outside layer, let it go matte, and run your hand over the outside. As it gets hotter and sets, you'll almost be able to polish the outermost layer with your hand. Before it gets hard, scratch some identification into the mold - someday you'll have enough molds that it gets confusing if you don't. Run a knife around the edges to remove any sharp bumps before it sets.
For the horse head mold, it should be 1.25 to 2 inches (3.2 - 5.1 cm) thick. It'll be heavy, but you'll get a lot of pulls from it.
Now, carefully remove the dam and the half-sphere keys. Smooth any damage to the sculpture from the dam. Make several one-inch (2.5 cm) wide by quarter-inch (0.635 cm) thick rectangles of clay, long enough to go from about a quarter-inch (0.635 cm) away from the sculpture to well outside the mold. These will be screwdriver slots to assist in separating the mold. Place several around the edge of the mold part you just did. Now coat the edge of the mold (where the next part of the mold fits, natch) with vaseline, covering the 'screwdriver slots' and getting into the key depressions. Make sure you cover the outside of the mold for an inch or so (~2.5 cm). Rotate and support the sculpture so the next area of the mold is horizontal and repeat the process to make this part of the mold. Repeat until all the mold sections are done. Leave it alone for a day or so to fully set.
Now, using long screwdrivers (we've got a set of 24" - 36" (60.96 - 91.44 cm) long screwdrivers), gently pry the mold apart using the screwdriver slots. It may take more than one person to do it - you're breaking the suction of the mold to the sculpture. Don't worry if some of the outer skin of the mold breaks off, and be warned that the sculpture will certainly not survive the process. Once released, take the mold apart and clean it out.
To do the cast, vaseline the mold edges again and re-assemble the mold. The shape of the mold and the keys should make it easy to align the parts. Hold the mold together with either large rubber bands cut from tire tubes or duct tape, or both.
Set the mold with the opening upright in a bucket (or trash can lid for one this big) and fill about half-full with latex. Slosh it around to coat the inside (and make certain the mold isn't leaking badly), then fill the rest of the way with latex. Let sit for an hour or so and pour back out (saving it, of course) and set the mold such that the latex can drain out (with the shape mold you're doing you'll have to roll it around some to get most of the latex out) and leave it *that* way for about fifteen minutes, or until it stops draining. Pour the latex that's now in the bottom of the bucket into a different container and label it 'build-up.' It's been exposed to the air too long and probably should not be used for casting again - it's too thick. Use your own judgement about it. Set the mold with the opening upright again and leave it until the latex starts to skin and change color - and repeat, leaving the latex in for fifteen minutes or so after that first time. The more pours, the thicker the latex. The thicker the latex, the more durable, but the less flexible. Somewhere around 1/16 to 1/10 of an inch (~0.16 - 0.25 cm)(three to four pours) is fine for front paws, up to 1/4 of an inch (0.635) for hind paws. If it's hot where you're doing the pours, the latex will set faster and the pours will come out thicker. Put a fan on the mold and turn up the heat if it doesn't seem to be setting at all.
It will likely take two days to do all the pours on your head. If you've ever cast with clay slip then you pretty much know what's going on.
If the mold leaks badly, duct tape around the seams and/or leaks, pour in the latex and immediately pour it back out again, and let it skin. This will usually cause the leaks to seal up. The vaseline helps seal the mold.
The end of the muzzle and the ear tips will take the longest to set - I've popped open a mold after letting it sit for a week only to find the ears still haven't set (and ruining the 'skin'). Leave it until all the rubber you can see is a uniform color - and give it another day just to be for sure. If you're rushed for time you can force the setting by putting the whole mold in the oven at 200 degrees F (93.9 degrees C) - but it shortens the life of the mold.
Pry the mold apart like you did the first time to free the latex skin; after the mold is open just pull the skin free of the mold.
You can also partially fill the mold and use a sponge to cover all the inside if you don't have enough latex to fill it completely - it just takes longer 'cause the pours aren't as thick. Our wolf heads take five gallons (18.9 Liters) or more to fill, so it can be a problem.
Hope all that helps, and hope I haven't left anything off or misstated it.
26.3 - Conventional, hot-set foam latex
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From: Lynx - VFP
Hot Foam - which is the best, but is more expensive, it is much slower
because you have to bake it, thus giving you more working time, which is
nice, and the foam itself is the softest and strongest foam latex there
it creates much better appliances and puppet skins with greater
elasticity. It's fine cell structure makes for invisible blending into
the edges of the face, this is *the* professional stuff for making
quality looking latex appliances. It is castable in most stone molding
materials, including fiberglass and silicone molds.
From: Lynx - VFP
Subject: Foam log
I just wanted to say, that for anyone who does hot or cold foam latex it is really good practice to keep a foam log for every time you run foam. You will use it and find it very helpfull. An example would be say the first time I did my new lynx nose for this years costume I have down.
Lynx nose, First run, 12/14/94
A: 25 g
B: 100 g
3 coats of liquid latex as mold release and skin.
Mold was allowed to cure for 1/2 hour
No run off
Air pocket in front of nose - should slush lightly next time.
sculpting note - Edges were thick
No problems releasing mold, no tears
And that's it, it's real simple, real easy to do, I keep all my foam runs in several small ledger books. I can easily go back and see what I did for the first run of my lynx nose should I decide to do another run, which is very helpful, exspeically remembering the A:B amount used, And it's good for lots of things besides just second or more runs of the same item, since you are naturally going to get better with each run, this helps your progress.
26.4 - Slushcast
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From: Lynx - VFP
Slushing - also know as slip casting is a natural latex material that has been pre-vulcanized, it has great elongation and excelent memory without permenant distortion, so if you want to make a mask that can take some real wear and tear this is the way to go, this is usually the way those quality haloween masks are made that look like a thick rubber. This is basicaly liquid latex with some filler. This is what I use for my skins, If I am slushing, I brush a thin coat of it into the mold to pick up all the detail and then pour a generous amount into the mold and like it's name I slush it all around the mold to make it cover all surfaces until dry.
26.5 - A-B (catalyzed)/cold foam
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From: Lynx - VFP
Cold Foam - also known as PolyFoam is a 2 part (A and B) polyurethane foam system, it is very soft, it's Excelent for body part construction such as arms, and heads, and very nice for small appliances such as ears. It is also excelent for large puppet skins and props (foam guns and clubs, etc..) The kind I buy is always self skinning, and I can't remember the density ratio right now, but it's increases in volume something like 300% It is known as cold foam, because it cures (not drys) without having to bake or heat the foam. It expands right away, once you mix the two parts you have between 45 to 90 seconds to work.
From: Furtech
Subject: FL: A little knowledge... (was: Cold Foam Help!)
...is a dangerous thing. Yes, the individual components of most A-B polyfoams are harmless, separately. You need to read the part of the safety book on what is released when the foam kicks (expands/sets). That reaction gives off several types of cyanide gas. Bad, nasty stuff (yes, the same sort of stuff they use to kill people in bad mysteries). When the foam kicks, it gives off a LOT of this gas.
When using A-B foams, best to do it outside, with a organic-rated respirator and goggles and a fan. The goggles are because some of the gasses/chemical fumes will get into your system via any membrane surface. Had that happen to me with monomer-acrylics.
I don't know how carcinogenic cyanide is, but aside from it's deadly effects (I forget the actual mechanism), cyanide also accumulates in the fatty dermal layer of the skin and at a certain point of saturation/accumulation, you get very, very sick. Detox is a long, nasty business if you survive the initial catastrophic collapse.
Then again, I am not familiar with the foam you are using: it's possible that there are no dangerous gasses thrown off when you mix it, but if what you are using is some form of polyfoam, you get cyanide gas.
Basically, do what Corey said to do, procedure and precaution-wise. Oh, and a lot of these A-B foams are temperature and humidity sensitive. Hot, humid days are the worst! Your foam will collapse like a bad souffle'
In response to Super Jay;
> Almost anything can cause cancer when exposed to it for long periods of time and
> in high quantities.
> The danger depends on the brand used and how the componants are used. In the
> 16page booklet that came with my Kryolan cold foam kit, listing the chemical data
> on the 3 parts of the kit they say:
>
> for the Part A of the kit (the brown tea colored part):
> A test done on rats:
> "In the absence of prolongued exposure to high concentrations leading to chronic
> irritation and lung damage, it is highly unlikely that tumor formation will occur."
> "Carcinogenicity: Neither MDI nor Polymeric MDI are listed by the NTP, IARC or
> regulated by OSHA as carcinogens."
> "Respitrator requirements: Because of the low vapor pressure, ventilation is
> usually sufficient to keep vapors below the TLV at room temperatures. Exceptions
> are when the material is sprayed or heated."
> "Ventilation requirements: If needed, use local exhaust ventilation to keep
> airborne concentrations below the TLV"
>
> for the partB of the kit (the white creamy part):
>
> "Carcinogenicity: Not regulated"
> "Respirator Requirements: None required"
> "Ventialation Requirements: No special requirements"
>
> for the release agent :
>
> "Medical Conditions Aggravated by Long-Term Exposure: Respiratory problems
> aggravated by breathing vapors."
> "Use in well-ventilated area"
> "Exhaust ventilation recommended"
>
> So basically when you're coating your molds with the release agent do it with a
> fan blowing and a window open.
> When you mix the foam, don't worry about the open window or having a huge fan,
> just do it in an open large room really. If you're mixing this in small
> quantities to make a prosthetic, head or even body parts, it's not dangerous.
> It's dangerous if you were working say in a factory where they're making cushions
> and stuff where they're mixing the foam in HUGE quatities to fill massive molds
> and you're exposed to the foam chemicals during your entire shift.
> Use a respirator if you want, but it's not entirely necessary.
26.6 - Silicone
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26.7 - Gelatine
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Notes from a seminar held by Matthew Mungle - http://www.geocities.com/Hollywood/Lot/9373/SCREAM/gelatin.html
26.8 - Vacuforming
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See section 8.8
26.9 - Vinyl
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26.10 - Liquid latex
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26.99 - Other methods
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From: Flinthoof *U*
MELTING RUBBER FISHING WORMS FOR CASTING
The use of rubber fishing worms in temporary molds is an old one that model railroaders have been using for over two decades now for small molds. However, while they do have good sides, there are some things to consider here...
1) DO NOT MELT THESE IN A MICROWAVE. If you must do this, use a hotplate outside in proper ventilation. You are melting rubber here, and that's one of them non-breathable thingies that you know aren't good for you to ingest into your lungs. Those are chemicals and certainly not good for your micro either as they will permeate the plastic liner of the oven and transfer on to future dishes. Besides, if they were good for you, we wouldn't have seen Spock looking into his sensor array and telling us that the planet down below had breathable concentrations of nitrogen, oxygen, carbon dioxide, and silicone rubber worms. :)
2) Use pliers! Or anything else that can handle the hot material. It's very runny and can cause intensive burns in a hurry.
Okay, that being said, let's see what we can do with this stuff.
Plaster masters work well, as do wooden ones as long as they are properly protected against the rubber from sticking. PAM works well, as does Vaseline slightly dissolved with MEK. (Use a respirator-MEK is another one of them nasties.) A cookie sheet as a base plate with walls built up of stripwood or clay work well. Sculptamold can handle the heat quite nicely.
The rubber molds are temporary. Once poured, they can be quickly force- cooled under cold water. The average life span of the molds is short, being 5 or so castings depending upon materials and undercuts. Best part of the molds though is......when done or if it's defective, remelt it! :)
Lastly, do NOT allow plastic to come in contact with the mold for any length of time. The oils in the rubber will tend to melt and eat through the plastic.
Happy Tails!