World's Easiest Silicone Mold.

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About: I'm a Community Manager at Instructables and the voice of the robot on Twitter! www.twitter.com/instructables Tell me what projects you want to see in our Twitter feed! When I'm...

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:

2018 Edit:

If you are looking to use this mold making technique to do life-casting or food casting, these molds are not skin or food safe.

I recommend these kits:

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!

____

This project uses affiliate links that help me make more awesome DIY projects and tutorials - thanks for your support!

13 People Made This Project!

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428 Discussions

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GisseD

4 weeks ago on Introduction

Would love to try, for a cement planter mold.
Do you know, how can I make the silicone more liquid?
Thanks!

1 reply
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LynnG64

4 weeks ago

Can this technique be used to make a silicone handle for a kitchen pot?

1 reply
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audreyobscuraLynnG64

Reply 27 days ago

I think for that, you would actually need to cast into a plastic mold, silicone can't be cast into a silicone mold.

If you know someone with a 3D printer, you can make a two-part mold with one of those, then buy the right kind of silicone that would pour and make that shape.

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SusanK160

3 months ago

I was a theatrical costumer and prop builder for about 40 years. I have worked with silicone of all types for years. I followed directions to the t. I kneaded the silicone for over 30 minutes and it gained only a mild firmness. Cured for 4 days, still sticky. Just how long do you have to knead this stuff? I also tried the silicone and cornstarch. It worked beautifully.

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MadelineJ5SusanK160

Reply 4 weeks ago

Not sure if you ever figured this out, but you must use TYPE 1 Silicone, which is safe to use in fish tanks. I had the same issue before realizing I was using Type 2 silicone.

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SusanK160MadelineJ5

Reply 4 weeks ago

hmmm...would have been nice to have that included in the instructions too. It did work ok with II once I figured out that the step to remove it from the water before you knead it was missing.

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audreyobscuraSusanK160

Reply 2 months ago

Huh, I've never had that happen! I wonder if it has to the with the temperature, or if not enough water was worked into the goopy mixture. I am yet to try the silicone and corn startch technique, but I just ordered stuff to try it!

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SusanK160audreyobscura

Reply 2 months ago

After speaking with others who had the same trouble I figured it out. Your instructions say "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."

I tried adding "Remove from water" before proceeding to the second sentence and finally got that horrible smell and it set. I work in a field where instructions must be followed exactly as written or research results are flawed. I'm sure I'm not the only one who had to make it twice to figure it out!

Dollar stores usually carry cornstarch you might try to get it there. I'm not sure which recipe you are using, the one I use is nothing but silicone and cornstarch. Here are some hints: I start by putting the cornstarch in the bowl first and spread it out. This keeps the bowl and process less sticky all the way around. If your recipe says to wrap in plastic, seal in a container and let sit, be careful. Depending on how much cornstarch you add that step is not always needed. I use this rule of thumb: if it is mixed and feels firm/unsticky enough you can use it right away. This method does not make the silicone smell bad either!

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MadelineJ5

Tip 4 weeks ago

Make sure the you use TYPE 1 Silicone, which is aquarium safe, and not Type 2. If you use type 2 silicone your mold will never cure.

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jogarcejAllan4286

Answer 5 weeks ago

For what I can see, it's just regular dish soap.

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PattyP17Allan4286

Answer 2 months ago

It is DAWN, and get only the blue color liquid. It has properties that no other dish soap has. I don't know what's in it, but it is called for specifically in a few crafts I do. I don't recommend actually using it to wash your dishes unless you wear gloves. It does a great job of cutting grease, but will strip the natural oils from your skin too and cause them to crack and bleed if you immerse your bare hands in it on a regular basis. I'm not the only person who has had that happen. I've actually met a random person with cracked bleeding hands and asked them if they used blue Dawn to wash dishes, and they said, "Yes!" The product has been used for decades to clean up animals in oil spill distasters, so it does have great uses. The manufacturer claims it is "gentle and safe".

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judy72649

3 years ago

Can you use it on a horizontal surface? I have a pattern on my fireplace I'd love to make a copy of.

2 replies
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I learned this technique when I was trying to replicate a motif on a tile in my old apartment - so yes! you can! just figure out a way to get the silicone to stay horizontal, Gaff tape worked ok.

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AlexK21

3 years ago

OMG, this was a perfect set up for what I needed. I proposed to my wife at the top of Empire Bluff in the Sleeping Bear National Lakeshore area in Michigan by carving Marry Me with our initials in a dead tree/drift wood. We visit every year and I have received it every time for posterity. I wanted to find a way to give her the carving for our 15th Anni since I have been carving it for that long. Your mold design was so simple that I secretly climbed the bluff trail with the materials in a backpack, completed the process at the log, and left the mold to dry overnight. I went back yesterday and got it and it a perfect negative of the tree. I can't wait to pour my resin and paint the piece to look like the log. Thank you so much for this instructable.

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doing2muchAlexK21

Reply 5 weeks ago

Alex, you have one lucky wife! Did the mold come away from the tree easily? I have some log stumps that I want to cast in concrete but fear the mold might stick to the bark. Any thoughts? Jen

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Louis-ClaudeT

Question 3 months ago on Introduction

I enjoyed your instructions on mold making. Have you tried making a two or three part mold? If you did, what did you used to keep the silicone from sticking to the first part?

Thank you.

Claude Thibault

1 more answer