Instructables
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.

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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.

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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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stinebusch3 days ago

This is amazing! I can't wait to try it out. I have some questions, maybe someone knows the answers?

How did you make it a complete figure? Cast the other half and then glue? Can you cover it in two halves of silicone? What's a good way to do this?

Can you cast any material, like plaster, fine sement or molten plastic in this?

Is it a good idea to use a bit of Vaseline on the casting object to make it easier to detach or is this simple anyway with silicone?

Cheeeers!

pocholox815 days ago
I am definitely getting a dinosaur just to name it Jesus, damn isn't that the smartest name! you totally changed the way I make casts thank you jesus!
lakisok23 days ago

I am trying to recreate a hand mold made in my patio concrete from my children's hands and our then dog's paw prints. The impression is in the pressed and colored material. We are moving to a new house and I want to preserve their prints for posterity. I think I may need 2 ft square more or less how would I apply it? and my idea is to then pour plaster of paris (spelling) over mold to recreate the original impression.... then air brush paint a patina. so Qs are:

1. how much silicone is needed? And how do I apply

2. what do you suggest I use and by what method should I apply the plaster

Cube_2 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

audreyobscura (author)  Cube_2 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

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.

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 ^^

No problem.

Polinom10027 days ago

Can you cast metal in this silicon mold?

audreyobscura (author)  Polinom10027 days ago

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

dalucero1 month ago

So just to be clear, the soap only speeds up the curing right? It's not required?

KzooK1 dalucero1 month ago

dalucero,

I'm not sure if the soap affects the curing, but it keeps the silicone from sticking to your hands and the mixing bowl by forming a release layer between you and the silicone. It doesn't have to be expensive soap; any clear (not creamy-looking) hand or dish soap from a discount dollar store would work ok.

kbeagle1 month ago

I would like to make a mold out of real strawberries to use in my soap making. I was in hopes to be able to put the silicone into something like a shoe box or smaller with about 10 strawberries, maybe 12. What would you suggest? Thanks!

VenialVenom3 months ago

Hi :) I love this instructable. I was wondering if you might know if this method of mold making would be safe to use with cooking. I would like to make some fondant molds but not sure if it is safe to put food stuff on this silicone. Thanks for sharing this project :)

Just passing along information. Be sure to check for food safe ratings! Interestingly enough many aquarium 100% silicone sealants are food safe (again, just keep an eye out for the rating). Aside from that most of the food grade sealants I have found can withstand 400F when fully cured!

example product, not favoring: http://www.amazon.com/Clear-Food-Grade-Silicone-Sealant/dp/B005XP5HO6

audreyobscura (author)  VenialVenom3 months ago

DEFINITELY NOT! I think there is food safe silicone, if you need it.

bgbdbill672 months ago

I will be testing this out tomorrow with this product on a candy mold. It lists on the package that it can come in contact with food. http://t.homedepot.com/p/DAP-2-8-oz-Silicone-Aquarium-Sealant-00688/100128841/

SaintAstra4 months ago

So I tried this and finally succeeded - right silicone, dish soap. The mold came out nice (any imperfections were my own fault) and it even dried within a few hours. I made two molds. I poured my resin and when I popped the piece out, it was eaten away and tacky, like the surface of the moon only a lot grosser. It wasn't cured all the way and the parts that had touched silicone felt like melted gummy bears. It reeked of vinegar (No idea why, since vinegar went nowhere near this project). The inside of the mold had resin residue, all tacky.

I waited a full day, washed the second mold out thoroughly, thinking maybe the dish soap reacted or it was a bad batch of resin. Nope - tried it again, this time put half in the silicone mold and half in another plastic mold for control. Resin cured fine in the plastic but was still eaten away and tacky in the silicone mold. Not just in the cavity - I put a drop on the flat part of the mold, and that won't even come off it's so tacky. I have absolutely no clue why this happened.

I used:
GE Silicone I 100% Silicone for the caulk (tried it with II and it was a noxious failure)
Dawn dish soap
Wilton Liquid Glycerin
EasyCast Epoxy Resin
Tap Water

I use resin to make jewelry, and it sounds to me like you need to try a new resin. It doesn't sound like the resin is setting right, which has nothing to do with the mold. I would try a different resin mix. Could it be there is something wrong with your product- too old, not mixed right by the company? Good luck in the future.

I just tried this method and it is super easy! Thanks so much. I used Dap 100% silicone. It has a very low odor that I am sure will dissipate over time. This method is going to save me a ton of money and much search time.

ukiran13 months ago

hey I am from India, has anyone tried from this part of the world, if so can any one let what ingredients (make of silicone) and can you let me know where i can find resin?

Thanks

jsrubianoch6 months ago

Is this food safe? I would like to make a mold for making candy lego.

jerrycwood6 months ago

Is there a limit on the thickness of the mold walls? I know that most tubes of silicone say to not exceed 1/8" thickness. Will this technique permit thicker walls?

tubaska7 months ago

thanks, Audrey.

can you tell me how to make right and left direction molds from an object?

eg, if I have a right facing giraffe, how do I make a left facing giraffe?

again, thanks for sharing, tubaska

audreyobscura (author)  tubaska6 months ago

Are you needing to make a 2-part mold?

it can be 1 or 2 part but I prefer 1 part as i'm using the pieces as cabs for my jewelry.

thanks, tubaska
kpsmree7 months 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

audreyobscura (author)  kpsmree6 months ago

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

maryd627 months ago

hi i need to make a silicone mold thats crystal clear. the objects i insert into the resin needs to be precise. what brand would i use. The mold needs to be as clear as possible. Thanks

audreyobscura (author)  maryd626 months ago

I don't think this method would work. All the molds are typically cloudy.

motleyjust6 months ago

Why does it need to be blue dish soap? Is there a particular ingredient in it that isn't in other colors of dish soap?

audreyobscura (author)  motleyjust6 months ago

No particular ingredient, it's just a way to visually measure concentration of the solution.

MicioGatta7 months ago

Great tutorial and great idea, I'll try it :)

maryd627 months ago

Hello, thanks for this, I need to make a crystal clear mold. Is this possible with that certian brand silicone?I need to place objects in the resin very precisely, so i need the mold to be as clear as possible. thanks

dhooey halim8 months ago
Please make an instructive on how to make the full 3-d object.
gtoal2 years ago
Read the "oogoo" articles on Instructables. They'll show you how to use corn starch (aka Talc, as currently formulated) to cure the Type I silicon far faster.
absomagic gtoal11 months ago
Yes but I have tried both methods and found that the corn starch is much trickier. It rapidly hardens and was difficult to work with on ensuring it was pressed well into detailed sections ( such as the teeth others have talked about). Using this method allowed more time to work with the material and gave great detail in the mold.
paqrat2 years ago
This is way cool. Have you tried it with the white silicone caulk?
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