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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.

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.
 
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What difference will it make if I don't use 100% silicone?
I only have acrylic latex caulk plus silicone

A lot of homemade silicone molds require 100% silicone. The additives (acrylic and latex) might interfere with the curing.

brown684 months ago

i advice you not to use on skin or (especially) anything penetrative, i"m an artist and did many casts out of body parts which in such case i used alginate which is extremely safe and the results are super fine detailed.

Where do you find alginate? I am not near a Blick store, and I would prefer to purchase it in person...

http://www.smooth-on.com/Dragon-Skin%3D-FX-/c1339/index.html?catdepth=1. Dragon skin pro FX is completely safe for penetration. They also sell alginate that's safe for skin girlfriend loves what I made her Works great

Can you reuse this mold, or do you have to make a new one for each cast ?

Lilbobtail21 days ago
Tried this and two hours later my mold is still really squishy and now it's tacky. Not sure what I did wrong.
BMm14 months ago

im a girl and i just want to ask if is it safe to make something penetrative (if you know what i mean) out of that 100% silicone?

Hahaha this is hilarious and a very good question. I wish I could "save" comments.

Hitlist BMm13 months ago

go for it if you don't have any silicone allergies. Need a model? LOL

audreyobscura (author)  BMm14 months ago

Hey there - i feel like this is the question i have been waiting for since I published this Instructable. I'm pretty sure that this 100% silicone off-gasses acetic acid as it cures - it would just need to be neutralized before....well. have fun!

thank you for the reply, one more thing. how can I nutralized it?

audreyobscura (author)  BMm14 months ago

http://www.smooth-on.com/Silicone-Rubber-an/c2_1115/index.html

audreyobscura (author)  BMm14 months ago

Maybe a baking soda bath? But this isn't medical grade tested - I would pursue further education about materials that may not irritate your skin. Or do some patch testing on your wrist of a neutralized cured silicone, at the very least.

lovethepug3 months ago

I tried this just the other night for the first time, it worked great!! It came out just like it said. Now I am having a problem coloring the resin. I bought the darkest color specifically for resin and its still too light. It gave me a baby blue and I need cobalt blue. How much of the coloring can I add before I mess up the resin? any other suggestions for alternative coloring methods?

I actually add acrylic paint to color resin. It turns out opaque, but its perfect if that is what you are going for!

EddieW426 days ago

Has anyone who has tried this method also used Smooth-On Mold Star? Smooth-On is very expensive, so finding an alternate would be great. But I'm wondering how this method compares as far as work-time and flexibility of final mold. I need to make a single part mold of something with a bounding box of about a 1' cube. So I will need to make a large amount of this molding material as well as need to cut it afterwards to extract the object and make a cast. Can anyone speak to the material's ability to be made in large quantities at a time, be cut after curing, and flexibility?

Thank you in advance

EddieW426 days ago

Has anyone who has tried this method also used Smooth-On Mold Star? Smooth-On is very expensive, so finding an alternate would be great. But I'm wondering how this method compares as far as work-time and flexibility of final mold. I need to make a single part mold of something with a bounding box of about a 1' cube. So I will need to make a large amount of this molding material as well as need to cut it afterwards to extract the object and make a cast. Can anyone speak to the material's ability to be made in large quantities at a time, be cut after curing, and flexibility?

Thank you in advance

liv1ers1 month ago

Hi and thanks for the instructions! I want to make a sugar mold by pouring boiling sugar into it. Any idea what materials I could use so that the sugar would not melt the mold?

AlexK211 month 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.
alannaross1 month ago
Hi I was wondering if this would be ok to use as a food mould? I was hoping to make a mould of Lego bricks and then use them for making cake decorations etc
Do you know if that would be ok with this method or if I'd have to find an other method?
I'm wondering the same thing..
audreyobscura (author)  Andreacatanese081 month ago

It off-gasses acetic acid as it cures, it would have to be neutralized before using.

Here is food-safe silicone, I would trust this vs. my suggested technique.

http://www.smooth-on.com/Food-Safe-Material/c1387/index.html

I'm going to have to try this! I do have a question: can you sculpt this at all? It looks kinda soft, would I be able to let it set for a bit then shape it? I want to make a resin base with a water ripple pattern on top.

audreyobscura (author)  wingedshadowwolf1 month ago

You can kind of sculpt it, I would say you have about 10 minutes of malleable time before it sets up and starts really curing.

icarusmed2 months ago
Hi there! Great idea and great instructable!! I've got two questions for you. First of all, you said it's clycerine the catalyzer. What if i use pure glycerine?? Aaaaandd... Most important thing.. Could common silicone be used to cast Silver?
d124c0 icarusmed2 months ago

No, the silver would have to be to hot for the silicone. Silicone can cast things at temperatures around 200c. Silver melting point is like 800c or something high like that.

yediknight2 months ago

Great idea! Where is the second half of the mold, did I miss it or does Glitter-Trex have no tail?!

d124c02 months ago

Could I mold a full object and then cut it in half with a exacto knife?

jessicavda3 months ago
Hi, thanks for this.
i'm trying make a mold from a marble.
Would it be possible to do this in one piece?

Thanks

Hi! I love this. Thank you! I am making a two part mold and the first piece is done and dry. I am using vaseline in between to keep them from sticking. Can I use the same dish-soap catalyzing bath from the first part, or do I have to make a new batch for another. Thanks so much!

simonsch6 months ago

Great post! I have used this mould making technique many times so I thought I would contribute a few tips of my own. Acetic cure silicone will cure much faster that neutral cure. for speedy results use acetic cure. I would recommend a coating of soap on the hands before plunging them into the water/soap mix as the silicone can still be a bit sticky even in the soapy water. Also too much soap in the water can cause the silicone to become lumpy and not consistent. This water curing technique can also be used for direct modelling of silicone sculptures.(see photo) I usually make the sculpture in small parts and then join them together at the end. Silicone can easily be coloured for this by adding oil paint. For those commenters wanting a two part mold using this technique, build a clay barrier to seperate the halves, same as all two part mould making, and a good wax based release between the silicone halves so they don't stick together. Cheers, great instructable.

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quirxi simonsch3 months ago

Woow, cool dino !

85rocco3 months ago

I've messed around with silicone caulk a bit myself and if I understand the chemistry correctly, silicone caulk cures in the presence of moisture, normally it's atmospheric moisture that cures the silicone from the outside inward but anything you add to silicone that can carry moisture into the silicone will make it cure. I've used corn starch for this but anything that retains moisture will do, a small amount kneaded into the silicone will cause it to cure en mass the same way it does with this soap and water trick.

shep623 months ago

Hi, When I was working in the pharmaceutical industry one of the materials we were handling was proteletic enzyme, this was used in a product that was designed to remove dead tissue around wounds which it did well but we had the problem of it digesting our top layer of skin even with all manner of gloves. Then we had a visit from a rep selling a special barrier cream. He said it would act as a barrier for most things, his demostration was to apply this barrier cream onto his bare hands and then pour Sulphuric acid over them! This was concentrated acid provided by our labs. The demo worked with no evidence of any acid burn to his skin. We purchased this barrier cream by the bucket load and never had any problem with loosing our skin to the enzymes ever again. Sorry about the long amble but there are barrier creames available for many differnet requirements. No gloves and the silicone would lift completely from the cream on the hands when washing hands after work.

MeganC23 months ago
jcurtacci3 months ago
so the silicone will not hurt the paint of the item?
just sayin3 months ago
Can you use this for chocolate or liquid sugar? You know.....to make the chocolate ,etc have a shape
rbloom2 made it!4 months ago

Thank you so much for this. I had ordered a prop that used the same gem featured in my pictures and it was a mess. I am sure that with your technique I will be able to create something much better. Thank you again! Also love that Jesus clone he's gorgeous! (Or she, is that frog DNA?)

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