Make a Silicone Mold From Common Household Materials in Your Kitchen in 1 Hour

Taking off from this BRILLIANT 'ible https://www.instructables.com/id/How-To-Make-Your-Own-Sugru-Substitute/ I have started making silicone molds on the cheap and thought I would share. This is incredibly simple and fast and can be used for a ton of casting ideas...

Here is the podcast I did on it:


The basic instructions are below....

Step 1: Materials

You will need:

• SIlicone Calking (the stuff that stinks like vinegar or acetic acid) I have a calking gun but you can get smaller tubes of it at the hardware store
• Mineral Spirits (this is just paint thinner but somewhat less toxic than the rest. NOTE: you can use white gas or camp stove fuel but be CAREFUL if you do use that. The advantage of white gas is that it will cure the mold faster and the mold will not smell like mineral spirits after)
• Corn Starch
• Vaseline
• Latex gloves (or what ever kind you like)
• mixing sticks
• Drill
• Bent nail
• Something to cast or mold
• Small box
• Mixing cups
• Wax paper
• Play dough

Step 2: Prep the Item to Mold

• To prep the item for the mold cover it with Vaseline (if it is a bit goopey use a blow dryer to melt the Vaseline and smooth things out).
• Next cut the bottom of the box out and place it on a piece of wax paper
• Get some play dough and fill the bottom of the box with a layer thick enough to cover half the figurine (don't put the figurine in yet this is just setting up the base
• Press the figurine into the dough and make sure to cover 1/2 of the figure
• Vaseline the dough and the figure (if it is a bit goopey use a blow dryer to melt the Vaseline and smooth things out).

Step 3: Make the Mold Material

This is where the coolness happens...

• Mix a 50/50 mixture of Silicone Calk and Corn starch in a cup
• Add some mineral spirits (or for those pyros out there white gas). You need about 25% of the volume of the 50/50 mix of silicone and corn starch
• Mix with your handy dandy bent nail you chucked into the drill!
• Add more mineral spirits if you need to to get the goop to flow
• Pour into the top of the mold base you made in the last step
• Get on to the next step before 5 min is up!!

Step 4: Pour Thinned Oogoo Into the Mold Base

• Pour the mixture into the mold base and level it out
• Place mold under oven hood (running) to gas off and not fumagate your house
• The mold half should set in about 5-15 minutes

Step 5: Next Half of the Mold

• Flip over the mold and peel out the play dough
• Cover with another coat of Vaseline (make sure to get all the silicone that has set up)
• Mix another cup of the Oogoo
• Pour
• Smooth
• Let set...

Step 6: Home Stretch!

Let this sit for about an hour to set up fully under the oven hood. We can now peel the bad boy apart.

Test the mold with some play dough by pressing it into the mold and seeing what comes out

Keep in mind the mold will stink like mineral spirits for about a week so let it gas off out side or in your shop. Otherwise use white gas it is much more dangerous (i.e. flammable) but makes a quicker curing mold that does not stink as much.

The mold will shrink about 10-15% after cure FYI

HAVE FUN and make sure to watch the video to clear any confusion up. There are more videos like this at http://MechanicalMashup.tv or join our facebook fan page at http://Facebook.com/MechanicalMashup

Comments

[minniekowalski]

Hi! Thanks for sharing this, I can't wait to try it. I was confused between step 3 and step 4: in step 3 you direct us to pour the mixture onto to the mold and in step 4 you instruct us to poor oogoo onto the mold. Are these the same thing or different things? Thanks :D

[lazychris2000]

Silicone I (also called silicone 1) is the type of silicone you need to use. The vinegar smell is acetic acid offgassing while the silicone cures. Read the tube carefully and make sure it says silicone I and/or 'emits acetic acid while curing'

Silicone II (aka silicone 2) is a different formulation of silicone, reacts differently when you add cornstarch and has different properties than silicone I. Siliconized acrylic is a completely different animal all together

[tablet1]

I made one side of this mold but this is wet after 24 hours i cant start another side

[Malicity]

Has anyone tried using water based caulk for this sort of thing?

[Jonny1128]

How much more will it shrink with 50% of volume mineral spirits

[treymartin82]

What temperatures can these molds with stand?

[C Diane]

I tried using 50/50 silicone and cornstarch since I wanted a more clay-like consistency to mold over an object. The stuff never dried and had to throw the whole thing away. I used GE premium waterproof silicone for kitchen/bath/plumbing (100% silicone and regular corn starch. What did I do wrong?

[ThisIsMyNameOK]

GE silicone will work, but only the GE 1, which is clear and smells like vinegar. It sounds like you used GE 2 or 3, which have different ingredients and will not work to make Oogoo. If you haven't done it yet, have a look at the original Instructable.

[CptanPanic]

ge silicone is different and will not cure the same with corn starch. you need to use regular silicone that smells like acid.

[rlyndallwemm]

Forty dollars worth of failure. Probably because the State of California does not sell proper Mineral Spirits. The first batch was too thick to pour. The second was better. None of it stuck to the item properly and just fell off it, distorting the pour box and pushing out the sides. Horrible expensive mess.

[ThisIsMyNameOK]

There are lots of other options for thinners. Take a look at the original 'Ible, and some of the others. Mikey77 prefers Naptha, if I remember correctly, and it seems acetone also works well, according to comments here. I would also recommend starting with a much smaller project so it won't be so expensive. I am planning to conduct my first Oogoo experiments later today or tomorrow, but only 1 Tbs at a time, until I find what works the best for me. That way it won't cost me any more than about $5 to try all the different mixtures possible.

Also, make sure you are using the right caulking. It only works with the clear one that smells like vinegar.

[JohnLThornton]

Thanks for posting this Instruction. I made it! Not a Play-dough toy, but a mould of an essential - and
tiny - part of my wheelchair, which would have cost hundreds of pounds
to replace (because I would have had to replace the entire footrest
system, even though only one tiny bit snapped off).

I found that
the best place to get right silicone is at the cheapest stores (in the
UK that would be Pound shops or Wilko). The posher shops sell upmarket
stuff which doesn't have the vinegar smell.

When doing my initial
test, the only alcohol thinning liquid I had to hand was Nail Varnish
Remover (an essential part of my tool box because I'm constantly glueing
my fingers together whenever I use SuperGlue!).

I needed to use only a few drops of the Nail Varnish Remover, along with a teaspoonful of cornflour and a teaspoonful
of silicone caulk (the caulk I used for my initial test had been open and sitting on my shelf for
several years).

The mould dried fully within a few hours and it worked
beautifully. Now I've got the bug I'm going to try and make a mould of
my favourite Buddha statue.

[ThisIsMyNameOK]

That is really cool. The best and most practical use for Oogoo that I have read about to date. And it's good to know that the nail varnish remover/acetone works because I forgot to buy mineral spirits when I went to the store for supplies yesterday.

I don't think dollar stores here in Canada carry things like silicone caulking, but I'll have to have a look and see, since it is a little pricey at Walmart and I have a lot of ideas for what I want to do with it. Thanks for the tip.

[ThisIsMyNameOK]

Oh, I forgot yo say, I keep the nail polish remover handy for the exact same reason. Have never managed to super glue anything yet without gluing myself in the process.

[MechanicalMashup]

NICE!
I never thought of nail varnish remover (here it is nail polish remover) Given you need less volume of it and it smells better in my opinion maybe that is what I should be using. Thanks!

How much mould shrinkage happened using this thinner?

[ThisIsMyNameOK]

Pure acetone is probably better than nail polish remover, which usually has other things added to it. If I remember correctly, Mikey77 did mention using acetone but said that it smells worse than some of the other options. I don't know, but I have some that I keep on hand for the same reason as JohnLThornton, gluing my fingers together, or to other objects, or both.... anyway, I will give it a try when I get around to making some Oogoo, which I hope to do later today.

[AlanS11]

Nail polish remover is actually just acetone if you need a larger qty

[JohnLThornton]

Given that the piece I was working on was no more than 12mm long, there was no perceptable shrinkage. But you've got me thinking. My Buddha statue is about 45mm high so I'll make a point of measuring the final product and record any notable difference. I think I've caught the bug! ;-)

[ThisIsMyNameOK]

Thank you for this excellent Instructable. This is exactly what I want to do with Oogoo. At least, one of about 50 things I have thought of so far. And thanks for the tip about using the oven hood. I really need a way to be able to work with it indoors, since I live in Canada and, to coin a phrase, winter is coming.

[cashfl]

My two cents:

1) My proportions: By volume: 1 part caulk, 2 parts mineral spirits, 2 parts corn starch.

2) I strongly suggest that you steep the caulk in the mineral spirits for at least a couple of hours or overnight even. I've been casting large head and it was a nightmare trying to do it off the bat; not even one of the large mixing its you use for drills would work until I had let it dissolve some..

3) A drop or two of glycerin from the drug store will insure gelling.

4) As has been noted, the GE caulk is tricky. I've been using the DAP brand with success.