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Old Sep 28, 2014, 11:35 AM
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Ultracal 30 alternative + New FTW source

Found on http://www.thehunterslair.com/topic/...-ultra-cal-30/ a movie make-up site:
Homemade Ultra-Cal 30

A lot of noobies or hobbyists use Plaster of Paris to create a stone mold for latex costume pieces. This is cheap and works great for most single-sided molds. But for masks or molds with a lot of curves it becomes a problem since the plaster chips and can break and fracture.

Ultra-Cal 30 is the "standard" and is a super strong "version" of plaster - industry professionals use it all the time.

Since it's heavy, it costs an arm and a leg to ship, and to me, that's a big deal since I have no local stores that carry the product.

Per the MSDS sheet for Ultra-Cal, you can cheaply make a version of it to use yourself. I did this, and I use it all the time for the added strength. This allows me to be more creative with sculpts and molds and also use less materials since it's stronger - instead of an inch thick mold, you can have a 1/4 inch mold that will be just as strong.

The ingredients:

Plaster of Paris

"Quickrete" Fast-Cure Cement

Gram scale

The ratio is 80% Plaster to 20% Cement, by weight.

For my recent mold (Wolf Predator chest armor) I mixed 650 grams of Plaster with 150 grams of Cement. My mold is around a 1/4" thick and came off of the mannequin with no fuss, no cracks, and no problems. The mold is strong and looks great.

I'd like to note that the MSDS sheet says: "85% Plaster, 10% Portland Cement, 5% Silica." Since I'm not sure exactly what Silica is or where to get it, I didn't bother with it and used the cement and plaster only.

The cement and plaster should both be powders. I mixed the powders together in one bucket and added the water (2 parts powder - 1 part water). The result looked, felt, and smelled like Ultra-Cal 30.

Reply:

I've used a mix similar to this in the past, but did use the silica (sand). We used type II portland, because it's what we had on hand. If I were to do it again I would go with the type III because of how finer it's ground. It wasn't bad, but the sand (which adds most of the strength to portland) leaves it pretty rough, especially if you can't get to it to trowel it smooth. I never thought about using this for molding, but it seems like it would work better than POP alone. I'm lucky in that I have a supplier for UC-30 about 1/2 mile from my house Good tip, thanks for passing it on.

New FTW source for Ultracal 30 @ $30 per cwt bag (no 50lbs listed) GRACO Aerospace Supply:

USG ULTRACAL A.T. 30 100 LBS/BAG

E-mail this product to a friend

USG ULTRACAL® 30 Gypsum Cement is traditional tooling gypsum cement specially formulated for close tolerance tooling. It is ideal for splash-casting molds and models for phenolic, polyester, and epoxy resins. It features exceptional hardness and accuracy, as well as the lowest expansion of any rapid-setting gypsum cement and is recommended where extreme accuracy and surface hardness are required, as in duplicator molds. The plaster requires 38 parts water by weight per 100 parts plaster, and after machine mixing, it sets in 25-35 minutes. For best storage results, keep indoors in a dry, stable environment, away from drafts. Do not stack more than two pallets high.

SKU: 03515
Weight: 100.00 lbs.

Regular Price: $30.72/ Priced by BG

I'll keep trying to locate a better price. Sure beats Freeman's Molding Supply's $52 but, hey it's gypsum it isn't a scarce resource either. Portland cement is about $8 /80lbs so Graco's price seems a little high too. The real problem is finding the best price so I'm asking if Home Depot or Lowes can special order and their prices.

Another forum member suggested using tooling gelcoat + one layer of fiberglass cloth then pouring 5Kpsi concrete on it to make a composite mold. It would be a guess some fiberglass stalagmites would be needed to lock the dissimilar fiberglass to the concrete, but that's just a thought. Using this method adding some steel wire or small rebar could be added without saddles & fear of sinking into the mold surface. I either case I'm certain a large >60" mold would be 'really heavy'. For you folks without a front end loader on a tractor that might be a concern!
From our ranch ED
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Old Sep 28, 2014, 02:20 PM
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That sounds like a real breakthrough Ed! Thanks for posting.
I also do not have a local source of UltraCal. So in due course, I will be giving this home made mix a go for a prototype model that I have planned.
One thing I would like to find a source for is sisal which has been used successfully in the past as a Gypsum based mould reinforcing material. However, I've not been able to find it. Perhaps this mixture does not need any further reo?
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Old Sep 29, 2014, 05:37 PM
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Jim, if I'm not mistaken, burlap cloth (possibly called "hessian" over there?) is made of sisal. Available cheap at craft stores around here.

Used to be able to get burlap sacks free from places like feed stores, but everything that was shipped in burlap sacks now comes in some sort of woven plastic sacks.
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Old Sep 29, 2014, 05:56 PM
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Yes Jim. I have some hessian in the shed. It could be cut up into random pieces and used for reo, that is for sure. I will probably use this in the absence of sisal.
However, the old unprocessed Sisal was not in the spun form, that is it was just a jumbled mass of fibres.
If you are old enough, like me, you will recall this was used to fill sofas and such.
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Old Sep 30, 2014, 02:02 PM
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Quote:
Originally Posted by Geek1945 View Post
Another forum member suggested using tooling gelcoat + one layer of fiberglass cloth then pouring 5Kpsi concrete on it to make a composite mold.
I found a standard ?typical? concrete density referenced at 2400 kg/m3. That's 150 lb/ft3. So rough calc: a mold 60"x8"x2" = 960 in3 = 0.56CF = 83 lbs. Aside from the clunky weight (and pretty much forget getting a vac bag around it) the thing I'd be concerned with Is essentially you now have made yourself a long, skinny 'patio block' which might be prone to splitting across the short side, maybe just laying it down a bit rough or maybe just a bit un-level. Some cast-in bars might be worthwhile, but maybe even hollow conduits/tubing to lighten the weight? If you connect the tubes to the mold flange uprights, that would solve the problem of suspending them in the slurry.

Poravor (oversize glass spheres like microbaloons on steroids are used in the concrete industry as an additive. But I guess if you can source that, may as well just make a poraver + epoxy mold like many have done & be done with all the concrete fuss.

I haven't worked with ultracal but Id almost be more tempted to replicate this gel+glass mold shell 'backfill' with it vs concrete, since it seems to have engineered low shrinkage properties. Thats another potential issue with cement type concrete. If its inch/inch shrinkage across 60" span is more than a hair, then it might part off the vertical glass flanges.
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Old Apr 05, 2015, 03:45 PM
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Quote:
Originally Posted by ptxman;29570282................................... ...
[I
I haven't worked with ultracal but Id almost be more tempted to replicate this gel+glass mold shell 'backfill' with it vs concrete, since it seems to have engineered low shrinkage properties[/I]. ..........................
Apologies for the late follow up, but I have been preoccupied with my current project.
I did some trials some years ago with plaster on top of a epoxy tooling coat. It simply would not adhere; I read somewhere later on that a special epoxy is required that will be compatible with water based plaster/concrete. My conclusion was that if I have to stock up on yet another epoxy (which might prove hard to find here), the perceived economic advantage of this system starts to disappear.
I have plans for another moulded glider after I finish the current one. It will involve a 1500mm span one piece wing. I'm tempted to try this home made mix as described above for this one.
Does anyone have any updates on this material to report?
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Old Apr 08, 2015, 02:45 PM
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Jim- the curing agent needs to be able to tolerate water contact or it will stay rubbery and may not cure at all.
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