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Picture of World's easiest silicone mold.
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Yep. That's right. I am about to change your mold-making technique forever. This simple way of silicone mold-making will have you wanting to make casts of all your trinkets and toys.

You will need:
  • water
  • blue dish-soap (any brand seems to work)
  • 100% Silicone (do not buy quick set silicone, you need 100% silicone)
  • bowl
  • caulking gun
  • something you want to make a mold of.
  • scissors/knife
  • masking tape - to patch holes in your positive, if necessary.
 
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Step 1: Make your catalyzing solution.

Picture of Make your catalyzing solution.
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By mixing a high-concentration of dish soap with water in a bowl, one is actually making a catalytic bath for your silicone. The glycerine in the dish soap accelerates the cure process for of your 100% pure silicone.

This is by no means an exact science, I use blue dish soap because it allows me to see how much I have added to a water bath, I approximate that I used 4 oz. of soap in 64 oz. of water.

Step 2: Catalyzing the silicone.

Picture of Catalyzing the silicone.
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Cut off the tip of the silicone caulk tube, and set it in the caulking gun. Unload enough silicone to surround the desired object, into the bath.

I use the whole tube usually.

Step 3: Preparing the silicone.

Picture of Preparing the silicone.
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While keeping your hand submerged in the dish-soap catalyzing bath, gently clump the string of silicone together. Form it into a ball, and slowly massage it. Fold it, stretch it out, and work it very much like one would knead dough.

When it begins to become a bit less malleable, and stiffen, it is time to sink your positive into your material. In this case, Mike helped me, and we used his dinosaur, Jesus. (hay-zoos)
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amvancourt6 hours ago
I've always used Oderless Mineral Spirits and/or WD-40 to clean hands of residue. Bonus tip: Do not smoke.

soooo...i made a mold just now, it's currently curing, and the silicone was NOT fun to get off my hands! Just a warning for those who have never used it. Any tips on how to get off the silicone?

Not sure of any easy ways of removing it, maybe try acetone.. Gloves might be a good investment :P

izzyev2 days ago

soapy water is to silicone as flour is to pizza dough.

Where did you buy your l.e.d.s and your resin? How long did the l.e.ds last?

So, if this mold is made from pure silicon, does that mean it's food safe? Can it go in the oven and freezer?

I need a exact mold of my hand. any suggestions ?

paqrat2 years ago
This is way cool. Have you tried it with the white silicone caulk?
I have. It... didn't end well. The pigment in it felt like it was burning my hands after I started pulling it out of the soapy water. I'd stick to using the clear.
Back when I had aquariums there were some folks making their own aquariums and someone said you didn't want to use some of the bathtube silicone caulk cause they have some sort of fungicide in them to prevent mold in the caulk. That may be what you felt on your hands.

Sounds like they really designed it to prevent mold! (get it? because molds)

Rubber gloves... problem solved!
I've had issues with the silicone sticking to gloves and generally becoming a huge mess. I suppose "huge mess" is better than, "it burns!", but I always preferred the greater dexterity.
Absolutely. These are chemicals. Soap removes the protective layer of oil on your skin, allowing the chemicals to penetrate your skin and cause potential harm, perhaps including nerve damage. I worked every with silicones for ten years, and have been given this info as professional training. Please, protect yourself. I know that sounds like your mother... there has to be a better way!
I think the safety issue is an important point an well made but it is also worth reminding that the silicone mix we are making will stick to silicone. I have used large quantities of this mix and tried to use a large silicone spatula to assist me with the mixing and of course I've still got mixture firmly stuck to it. However the cheap rubber gloves available in uk thrift stores don't stick at all.
Rubber gloves wouldn't stick to the silicone caulk?
It needs to be 100% Silicone caulk, aka "the clear stuff". Most of the other Silicone's actually have latex and other additives mixed in and don't work well at all. Plus, they are more expensive.
That's important enough you should mention it in the 'ible itself!
I had trouble with white silicone but great success with same brand grey silicone!
audreyobscura (author)  paqrat2 years ago
I haven't - if you try it let me know how it goes!
I think I have some white silicone tub caulk. I'll check it out and may try it this Sunday.
paqrat paqrat2 years ago
Turns out what I have is latex. I'll try picking some up though next time I hit the store. I think I'll stick with the clear though.
AudreyObscura(CoolName!): To add to your great guide: A neat trick I found online a few years ago, is to add a few drops of Acrylic(!) hobby paint( about 2-3drops per dixie cup of silicone caulk ) and mix well. The Acrylic paint also acts like a nice colorant and mix indicator, but it's water contents causes the silicone to cure solid throughout the mold like regular 2part molding compounds. I think this is what the soap is also doing.

I've used this to make custom insulators and rubber-Sugru-like items. If you want a courser texture add a little cornstarch. -Lee Studley
kpsmree1 year ago

Done this today. I'm still waiting for it to set. How long will it set? I did full object (chicken) mold. I'm planning to use clay afterwards for my chickens. Hope it will go all well.
*fingers crossed

Clay will not work for this application. If you want to slip-cast, you will need to make your negative out of plaster. Plaster is porous, which sequesters the clay's water. If you still have your positive, make a plaster mold from that. If you only have the silicone negative, cast a plaster positive and then cast a plaster negative from that.

audreyobscura (author)  kpsmree1 year ago

Awesome! You should share with the I Made It Button!

DaniellaN27 days ago

i made this mold yesterday but the mold still hasn't dried yet does it take a long time to dry? if it doesn't dry how can i remove my peice out of the silicone?

Polinom1007 months ago

Can you cast metal in this silicon mold?

yes

audreyobscura (author)  Polinom1007 months ago

I've never tried! Maybe low melting point metals like pewter

Cube_9 months ago

This doesn't seem feasible for larger projects, how dissapointing. (I'm make various custom things and decided I want to make two custom electric guitars for myself, one out of wood and another out of either fiberglass and resin or carbon fiber and resin (with a custom airbrushed paintjob) and a silicon mold seems the best option for this (since the resin one will be the same design as the wooden one)(
Any suggestions for how to make a silicone mold for large objects?

equal parts cornstarch and silicone using baby oil to mix it well into a paste them spread it over your item that you want to mold. it cures quickly so work fast

I wouldn't recomand it for large items. Silicon is quite expensive, the fumes are very strongs and you need to work very quickly. Once you set the first mold you won't be able to add a second one.

Ooo, handy tip: thanks!

audreyobscura (author)  Cube_9 months ago
Hey there! I have used this technique to cast larger objects....sort of.

My methodology is to make cardboard, or coroplast negative molds, and then coat them with silicone. The Silicone doesn't machine all that well, but I have found that cake decorating tools are the best for spreading it, and making even layers.

Cheers!
Audrey

that's really not feasible for my projects, I was hoping I could just build a square of wood and put the object in it and pour silicone over it (once it solidifies I could just flip it over and pry the object out)
My workflow will require the additional structural integrity to make sure the mold doesn't deform too much while I apply carbon fiber and resin (causes air bubbles and looks bad, sometimes it cracks altogether)
Further I'd prefer if the mold was re-usable

Any idea how I could achieve this? I tried googling it but apparently most people don't cast very large objects

The Rambler Cube_8 months ago

If you look into costume and prop making I think you'll find some pretty decent sized items being cast. The silicone of choice tends to be a Smooth-On product. I haven't personally used it, as it is a bit expensive to just play around with and I haven't needed it for anything that justified the expense, but everyone who uses it swears by it.

Cube_ The Rambler8 months ago

Oh? This seems to be what I need actually
"Project Specific - Smooth-On's wide range includes mold rubbers that can be poured on , brushed on , sprayed on or pressed on to any original sculpture and will reproduce detail perfectly. Reproductions can be cast in urethane plastic, epoxy resin, plaster, concrete, and more."
thanks ^^

The Rambler Cube_8 months ago

No problem.

Pompom1 month ago

Does the temp of the water matter?

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