World's Easiest Silicone Mold.





Introduction: World's Easiest Silicone Mold.

About: I'm an Instructables success story! After relying on the site to DIY my way through art school, I was able to join the Instructables Design Studio in 2012. It's the best! Whe...

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:

Step 1: Make Your Catalyzing Solution.

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.

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.

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)

Step 4: Make Sure the Mold Is Water Tight.

The best way to make sure your mold is watertight is to add a kind of thick-ish layer of silicone to the surface area of your object. Note how the dinosaur is padded by about a 1/2" layer of silicone all around its body. Also, I have left a considerable amount of the dinosaur uncovered, as I am only casting half of this figure.

You want to make sure you can still wiggle your figure out of your mold, without any of it getting caught, otherwise it can be very tricky to extract once your mold has set.

Step 5: Let It Cure.

It will take about an hour for a full cure of your mold, before you can use it. Allow your object to remain in the mold while it cures. When the mold is no longer tacky to the touch, and feels rigid, gently remove your positive.

We kept this mold on top of the fridge, and put a bit of soapy water down on the plate so that the silicone didn't meld with the paper plate.

Also, this part smells awful. Make sure you do all this in a well-ventilated space.

Step 6: Use Your Mold!

We made a sparkly rendition of Jesus with clear casting resin and glitter. When the resin began to gel we set three LEDs inside of him. Behold the sparkliest light up dinosaur in West!


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402 Discussions

Can you use this process to make a full mold, not just half of the figure? I need to make an ice sculpture for a challenge. I wonder if I can use this process to make a mold of a plastic action figure that i could then possibly cut in half to remove the plastic figure (positive) and be left with the negative mold in 2 parts. Then if i can figure a way to glue it together with a hole to pour water into- i could then position to make the needed ice sculpture. Then once frozen, i could cut away the mold to reveal my figure - What are your thoughts on this?

1 more answer

There are multiple videos on youtube showing how to do this. Search for "DIY 2 part silicone mold". Also check out the Smooth-On company website for many useful casting and molding technique videos.

I'm trying to add a silicone 'lip' to an existing dustpan, to make it pick up the little dust bits better. Do you think the silicone would attach? Should I score up the edge of the dustpan to make it adhere better? Should I put the silicone straight on, shape it, and let it cure, or use another method? (If there's a better place to be asking this in, please let me know!)

7 replies

Silicone sticks to almost anything, but polyethylene is almost impossible to glue to. Maybe start with a dustpan made of something other than polyethylene.

I’ve not tried to glue something to a dustpan, but I have found “gorilla glue” works well on none pourous surfaces, I even glued a 4” chunk of granite to a piece of glass it held for years. In fact it’s kind of impossible to get it to come off.

Glass and granite? Piece of cake. Now glue a polyethylene bag to a silicone rubber ball.

Maybe you could drill or punch a series of holes along the edge of the dust and and allow the silicone to ooze through them creating a thin layer underneath the edge of the pan. Of course you could use duck tape over and under the existing lip, creating a thin extension of the lip.

The one part silicone that cures with moisture sticks to things, which is why it is used as a caulk. But cured two part silicones (tin or platinum) won't stick to any nonporous surface except the same type of silicone. While mold release will prolong the mold life; it is really only critical when casting silicone of the same type. Note that tin silicone inhibits cure of platinum silicones.

Hey, how about Sugru? Google it and check it out.

Silicone will stick to that dustpan no-prob. I would score it and clean it with alcohol first. If you need to shape it into a lip, maybe look at some grout tools to help you get the shape right. For this use case you could even use quickset silicone, and never mix it with water or soap.


3 months ago

This is my first time on instructables and this article catch my attention because also I make a dinosaur mold for cakes. Congratulation!!, it is asome.

Quick question can I use food coloring with the dish soap or would it influence the colour of the silicone?

I tried several times to make a mold from a ceramics figurine (unglazed) I made for the project. But the silicone always sticks way too good to the figurine, thus not leaving a very smooth mold. Also very hard to get out.
I never tried to cure it in soap water first, but do you really think that would make the trick? I tried to cover the figurine in oil first, but made no difference.

Now I just have a figurine with a lot of silicone residue all over it, and I can't figure out a way to clean it off efficiently so I can start over

5 replies

Ceramic is a pretty porous material, even when glazed sometimes, and the silicone loves to stick to it for that reason. In my experience, using the soap water bath will not change the unfortunate results very much if at all. I don't know a good method of cleaning a silicone stuck figure besides burning the silicone off and I wouldn't advise using ceramic objects for this process, ceramic just doesn't want to play nice with silicone.

If you are still bent on casting it, you could maybe coat the ceramic figure with some sort of resin after it is cleaned to give it a less porous surface...? Something to look into perhaps!

I'm not too keen on getting it glazed, because I want to keep as many details on it as possible

Hi Mikki! I am an instructor for porcelain and ceramics (35 years) and I tell you that so you know I am not blowing smoke but know the mediums enough to give you help. You can glaze any bisque piece with 2 smooth coats of clear glaze and not lose the detail of your piece. Over coverage is where most folks lose some of the details but you will never be able to get a nice mold from a piece that is not smooth to start with. The mold only replicates what you have, and exactly as it is. You're mold will be so nice once you prepare your ceramic item correctly, and your pieces you pour will too! Good luck!

I have worked with silicone on home repair projects. when I want it to stick to one surface and not an adjoining surface, I slightly, very slightly dampen the surface I don't want it to stick to and powder it with baby powder. This works when you are laying down a bead, but if you move the work too much, the silicone will absorb the baby powder. Otherwise it works great.