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Mold Making with Jello

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Have you ever wanted to make a mold and cast something -- but were discouraged by the cost of casting supplies? Have you ever just wanted to make one duplicate -- rather and one thousand? Perhaps you only wanted to make one or two chocolate book marks or plaster casts of an ink jet cartridge...


Well, here's a very DIY, cheap an recyclable method to make molds for relatively low temperature casting.
 
 
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Step 1: Materials

You will absolutely need:

Gelatin -- I'm using Jello
Water
A vessel to pour in that will hold your positive item
Mixing container
Mixing Stick
A refrigerator with space for your vessel

You may need:
Skewers or other support device
Hot Glue
Tape

You probably want:
Chap Stick or Vaseline (chap stick being "edible")

Step 2: How Much "Stuff" do I Need?

This is very easy to determine.... But first, here's some rules for the positive.

1. No undercuts - that is, if the mold material goes over (or into) your positive - you won't be able to get it out (without some surgical maneuvers).
2. Avoid super fine detailing - I haven't experimented with this yet, but it seems like it would be bad.
3. Don't let the positive rest on the "floor" **

So how much gelatin do we need? Lets do a "dry" run.

First, place your positive into your vessel. Now, fill with water (you may need to hold your positive under). Next, remove the positive and measure how much water is left in the container (you'll probably be pouring off into a measuring cup).

You will need one 8oz serving package of Jello/gelatin for every 3/4 cups of water. I have not tried higher concentration (yet), but feel free to experiment as a less "jiggly" mold would be better.

** There is an exception to this rule. That is, if your positive has a flat side that doesn't matter (like the back side of a chocolate bar) - it is beneficial for that back side to rest on the "floor" of your vessel. This was the case for the Tetris Ice Cube Tray.
drcrash6 years ago
I just came across a couple of books with interesting information on making gelatin molds and agar moulage molds. Turns out gelatin is better than I thought, and used to be common for low-volume casting (up to a few dozen things, I think.) Very interestingly, it IS reusable---you can melt it down and use it to make another mold 5 to 15 times. Cool. (It's not as reusable as agar moulage, which you can use 50 to 100 times.) To make a gelatin mold more durable, you can swab the surface with a solution of alum and water. That will make it tougher and more heat resistant. (1/4 pound powdered alum to 1 pint hot water). You can then apply a mold release that's just stearic acid in kerosene. (melt 1/4 pound stearic acid and mix it with 1 pint kerosene.) To make the molds last a lot longer, you can use mostly glycerin or propylene glycol rather than water when cooking up the gelatin. It will dry much, much more slowly and you can get a bunch of casts out of it over several days. For details, check out "How to Make Professional Molds and Castings, from Plaster to Plastics" by Ralph Travers. (If your library doesn't have it, they can get it by interlibrary loan; that's what I did.) For agar moulage recipes and instructions, check out "The Materials and Methods of Sculpture by Jack C. Rich. I did some research, and the best place to get agar agar powder is usually from a local asian grocery store. Most of them sell "Telephone" brand agar agar in .85 oz. packets, and it's good stuff. The big advantage of agar agar is for lifecasting. It has a low melting point and an even lower re-solidifying point. (It has "hysteresis," meaning it doesn't like to change state, so you can let it cool well below its melting point before it will go ahead and re-solidify. For life casting, that means you can let it cool almost to body temperature before putting it on somebody. For non-lifecasting, gelatin is likely better. I think it's tougher, and easier to apply, and its higher melting point means that you can cast things in it that get pretty warm when they set. (But not really hot.)

Hi! I would love to try out the agar agar moulage method with my sculpture students at the local art school. Sadly the libraries in Latvia dont have the books you mentioned and amazon doesnt post to here either. Would you be so kind and please tell me the recipe I could use? I was thinking of casting their faces with this method+ plaster bandages.

Best wishes,

Laima

sebdokuba1 year ago
Nice, Gelatin who would of thought of it for other things besides silly fun. I have heard a similar and purchased a casting that is recyclable from a company called Composi Mold.
Still yet to microwave my food safe mold material. It's very hard to the touch and smells sweet like candy. Appreciate the insight. Is there a way to use the non-flavored gelatin in the same manner?
woooshhhhh1 year ago
I have witnessed some great jello casting before when I was a culinary intern out of school. I have tried unsuccessfully to find some of those chefs who worked worked out the kinks (facebook. . .)

They used Knox gelatin (unflavored) and made a super tight mixture - enough to fill a 5-gallon pickle type bucket.

They would invert & weight busts of presidents, plaster easter bunnies / bunny heads / animals etc. with an under tray to catch the spill-over.

After the bucket had hardened in the walk-in cooler, a quick dip in hot water (steam kettle) and the entire mold comes out of the bucket.

Careful cutting around the item and laying out the cut gelatin like flower petals on a table made reassembly easy.

The cut outs were re-assembled either in the bucket or with duct-tape.

They then poured in a mixture of chocolate & wax.

After flattening the seams, you had an identical replica in shelf stable chocolate.

lizz11552 years ago
Have you ever tried doing this with agar-agar instead of gelatin? (Agar's kind of the veggie substitute for gelatine, but it melts at 85 degrees C and solidifies between 32-40 degrees C, which could be more convenient than gelatin). I'm trying to work out whether this might be suitable for life-casting a hand?
dubit12 years ago
could i cast a hand or fot in this
trebuchet03 (author)  dubit12 years ago
Unfortunately, no. I tried this a few times with super concentrated batches of gelatin. I placed the gelatin container inside a bucket filled with icy water - and then left my hand inside for 1.5 hours. Hands are just too hot - the gelatin doesn't set around your hand :/
this works wonderfully on fairly small or light objects. unfortunately, this time, i needed to make a cast for heavy stuff. after several disasters trying various ways to cast my husband's tools (hammer, wrenches, screwdriver)--they are a little heavy for most suggestions,( and he'd get ticked if they had jello, silicone, etc on them,) my daughter &i had an epiphany. salt dough. 2pts flour, 1 pt. salt, 1 pt. water. kneaded it until it felt like clay. we used 1/2 the salt dough on the bottom of a lg. cookie sheet, put cheap plastic wrap on it, lightly pressed in his hammer, wrenches, & srcewdriver, put more plastic wrap on top, and the other 1/2 of the salt dough on top of that, pressed it down pretty firmly, and froze it for about an hour. after we removed the tools (by tugging the plastic wrap) we had 2 half molds. the chocolate also set up very quickly. so, the hubby gets life size peanut butter cup tools on father's day.
jujibelly4 years ago
To be honest I only clicked this instructable because I thought the picture was the brain bug from Starship Troopers...cool none the less.
This is for larger scale molds, but it's really cheap. You take a bucket of soapy water, the soap keeps the silicon from sticking to you, and then you squeeze an entire tube of "GE silicon sealant" into it (apparently you have to use the stuff that stinks, it won't work with the unscented kind), you then pat at it gently till it sort of balls up in your hands, if you press hard it will stick to you and it's a bear to remove, but you can handle it very gently till it starts to cure and then you will be able to remove it from the soapy water as a ball and mold it around whatever you were planning to make a casting of. In 12 hours you can cut it from your item and viola! You now have a clear silicon mold that will last for 5 years and that cost under $10 to do. Apparently it's really good at showing details as well.
shortone5 years ago
HELP! I really want to cast my hands/arms in plaster for an art project but I can't figure out anything that might work...the jello molds seem close enough but I don't know how I could get my hands out after the jello set without damaging the arm part of my mold. Also, I don't want to have to order any weird mold-making stuff.....i live in a tiny town so jello is about the only thing i could come by... some advice please??
mold each hand in a long thin container like a juice pitcher. When it is set, pull the whole jello thingy out of the juice container and carefully cut it in half. Then carefully put the two pieces back in the juice container. And voila, you'll have your arm/hand mold. You'll obviously need an assistant for this.
trebuchet03 (author)  gluneau5 years ago
Can you post pictures of how your mold came out? I've tried this - using half gallon milk jugs (the tall type) and then that jug was placed in a 5 gallon bucket of iced water to set the jello.... The jello started to set everywhere except around my skin as my body heat didn't allow it to get cool enough.
yeah that's what I've found as well. luckily I've managed to find a different mold-making material :D
trebuchet03 (author)  shortone5 years ago
Jello isn't the way to go for life casting - your body heat keeps it from setting....

Personally, I'd use alginate. It's a fairly common life casting mold-making item which should satisfy your "no weird mold-making stuff" requirement.

Douglass and Sturgess has it - it's called Dermagel (the same stuff used by dentists to make molds of your teeth):
http://www.artstuf.com/DStockNEW.fm$RETRIEVE?sortcode=BC030728&html=display

You can also use Moulage - which is basically like Jello and reusable ;)
http://www.artstuf.com/DStockNEW.fm$RETRIEVE?sortcode=BC030733&html=display

No worried about living in a small or even tiny town... You have internet access, so you're not so remote that mail can't get to you ;)
I actually ended up just dipping my hands into melted (but not insanely hot) wax and then filling the wax molds with plaster, which worked really well! alginate does sound like fun though...as soon as I get more money (haha...not anytime soon) It would be fun to try out. :D thanks!
will that survive the temps of melted aluminum?
That's something like 1220 degree F, if I recall. 660 C.
trebuchet03 (author)  HisDivineShadow5 years ago
Negative... But, you can use an intermediate material to make a positive mold for use in investment casting. I'd experiment with molten wax - maybe freezing the jello to give it some extra thermal tolerance would be beneficial. But do it, try it - then post an instructable :) Gelatin is cheap, and reusable - so ask yourself: Can you afford not to? :D
intermediate material?positive mold? sorry Im kind of new to casting also wouldnt the aluminum just thaw the mold?...then burn through it getting all over my back "patio" or are you saying it would make a chemical reaction making the mold stronger?
trebuchet03 (author)  HisDivineShadow5 years ago
No, you don't want to use jello as the actual mold for aluminum... You'll want to cast an intermediate material (intermediate meaning a step in between the jello mold and aluminum). Wax, for instance. Then you can use the investment casting process to make a mold suitable for aluminum. A positive mold is a mold where material is applied around it such that the inner surface of the part is representative of the mold ;)
wouldn't wax melt how a bout "quick crete" thats more accessible in my area
trebuchet03 (author)  HisDivineShadow5 years ago
The whole point of investment casting is to melt the wax out of a female mold to leave a material that can handle the heat of molten metal.... If you're serious about making something using molten Aluminum, I think you need to do a bit more research on techniques etc. before continuing... I'd start off with basic Google searches on investment casting ;) This way, we can communicate effectively on the subject.
ok thank you
Very nice setups. I want to make a lens prototype using this. I need colourless jello.....how can u help me.
Use plain knox gelatine. It's clear.
knox gelatin isn't clear its yellow
heathbar645 years ago
Forgot to mention earlier, I remember in an old magazine, instructions to make gel lenses like for 3d glasses out of gelatin, with way less water. From that I guess you could reduce the amount of water in your jello quite a bit and get some really rubbery molds
heathbar645 years ago
hey cool, I was just reading my copy of thurstun james prop builders molding and casting or whatever the book is. I found proper moulage is quite expensive, so the Idea popped into my head, "why not use gelatin to make a mold?" and what do you know?, good old instructables has the info. Btw, no that book doesn't tell how to make your own moulage. I've read it several times. But it does have a lot of other cool idea's well worth the read.
patmac5 years ago
could I make a jello mold and pour jello into it? In other words, I want to make something out of jello but I don't know if it will stick to the jello mold.
trebuchet03 (author)  patmac5 years ago
Potentially, if there's enough grease to serve as a mold release... I tried, and failed :/ But if there isn't, you're essentially jello welding :p
maxeen5 years ago
I am going to mold a ballistic gel object in it and make it a airsoft tartget
drcrash6 years ago
You can use gelatin to make a better molding compound called "moulage," which is a rubbery solid that you can melt in a double boiler, apply warm, and let it cool to make a mold. The best part is that moulage is reusable many, many times. It used to be popular for lifecasting, before alginates. (You heat it up to 115 F, let it cool almost to skin temperature, and apply it.) I think there's a recipe for making your own moulage in Thurston Jame's classic book, "The Prop Builder's Molding and Casting Handbook." Check it out. (Great book, covering molding and casting in 30+ materials. You can find it at www.build-stuff.com, or likely at your library.) I recently found out that some urethanes can be cast in damp molds like alginate molds. I'm guessing they'd work in moulage molds, too.
Do you have any instructions for moulage-making or know of any free websites with the info?
drcrash drcrash6 years ago
Oops, typo, sorry. The author's name is Thurston James. I think moulage-making would make a great instructable.
ravebot6 years ago
chicken poop?
stasterisk6 years ago
Crisco makes REALLY GOOD mold release. Just smear that stuff on. I made a bunch of white chocolate oranges this morning.
Yo! T! Check it out, worked perfectly.
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What did you make the second dog out of?
It's plaster, because of the need to keep the gelatin firm I let it harden over night in the fridge.
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