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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.

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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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kbeagle2 days 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!

dalucero7 days ago

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

VenialVenom2 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)  VenialVenom2 months ago

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

Cube_1 month 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?

audreyobscura (author)  Cube_1 month 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.

bgbdbill6726 days 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/

SaintAstra2 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.

ukiran12 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

jsrubianoch5 months ago

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

jerrycwood5 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?

tubaska5 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)  tubaska5 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
kpsmree6 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)  kpsmree5 months ago

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

maryd626 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)  maryd625 months ago

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

motleyjust5 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)  motleyjust5 months ago

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

MicioGatta5 months ago

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

maryd626 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 halim7 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 gtoal10 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?
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.
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?
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