Make a silicone mold from common household materials in your kitchen in 1 hour

Taking off from this BRILLIANT 'ible http://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

Comments

[cathypeek]

I want to make triangle shape crayons from melting old wax crayons. Is it possible to pour hot crayon wax into this type of mold?

[offtherails2010]

Also im going to be making a shed-load of molds for pouring casting-resin into (potting) and the resin cures by a chemical reaction causing the tepmerature to rise to about 60°c (140°F) and will be using a silicone caulk thats rated to be temperature resistant to upto 300°c (572°F !!!) !

The one i bought is called 'Heat Mate' in the UK (bought from my fav specialist shop, ebay, lol !)

Plus im going to be using this heat-resistant silicone to make some RC Buggy Parts that are located next to the engine so that it can better protect against a very high heat source !!!

Hope that helps !

[MechanicalMashup]

Yes it is... The temp of the crayons melted is fine with these molds

[cathypeek]

Thanks for your reply. Realized I needed a 3D triangle shape so I purchased sculptey clay to make it. I am going to try making a mold but need to watch the video again. I'll let you know how it goes. Thanks again!

[offtherails2010]

*** !!! DUDE !!! ***

I'm back to finally test out your GREAT instructable !!!

i just have a question whilst i wait delivery of some Play dough !

Instead of using mineral spirits, would you think it'll be a good idea to use 99.9% Isopropanol as its the closest thing i have to any kind of spirits ??!!!??

[grunt1612]

hey guys if you guys need silicone RTV contact this guy its pritty cheep [e-mail]

[mschell1]

if you dont add the mineral spirits, does the mold still shrink?

[MechanicalMashup]

With no mineral spirits the mold will stink but very very little compared to a mix with mineral spirits. With glycerin it will stink but more than no additive and less than mineral spirits...

[MechanicalMashup]

Glycerine does not thin as well as mineral spirits but definately does not smell nearly as bad. Remember that when the silicone kicks it will smell very strongly if vinegar or acetic acid...

[Lonecoon]

You can also use Glycerine to produce a mold that won't shrink, as glycerin adds the necessary moisture content to the mold.

[MechanicalMashup]

Ill have to give that a try. Where can you buy glycerin? I assume a pharmacy will have it?

[mschell1]

have you given this a try? i am about to go out to the store to get the materials for this project and i need to know what i should be getting, the mineral spirits or the glycerin?

[Lonecoon]

It will be in the laxative section, or in the beauty supplies. You can get the in droppers. You need about 3 drops per ounce of silicone.

[cakeladyd]

Hi, I am very interested with this technique, is it food safe? Could I use Sugar Paste and it not be harmful to the cake? thanks

[MechanicalMashup]

No its not safe for food. Using solvents in the silicone and the silicone itself will leach into the food and essentially poison it.

[cakeladyd]

thanks for the update, very helpful, guess I am back at the drawing board or just spending the money to get the regular stuff. thanks have a great day

[Batness]

You can buy basic supplies from a lot of retailers cheaper than the "regular" stuff...it's a good "in-between" compromise.
http://www.makeyourownmolds.com/how-to-make-molds

[just pick a name]

To deal with the shrinkage problem, you might try just painting on a thin layer of this thin mix for a detail skin and back-filling with regular oogoo after it sets up. Since silicone sticks to itself quite nicely, it should work. The only thing I wonder is if the skin's higher shrinkage would tend to warp the mold. My guess is that if it's thin enough, it will be held stretched by the regular oogoo.

[swankaliau]

Hi i need some help for making a big mold for faux stone .Could u pls tell me the ratio of silicone calking that you've used in the mix? And could the mold handle wet mortar on its surface?RTV is sooo expensive and this is a great idea for my students building project. studentsbuildingprojects.blogspot.com

[MechanicalMashup]

Oh and wet mortar will not be a problem

[MechanicalMashup]

I really did not measure it was just a by eye and feel thing. One thing to keep in mind is that the more thinner you use the more shrinkage you will have in the mold.

[EngineerJakit]

think this could be used for making plastic injection molding stuff? Im trying to make some merchandise for a person I know. She has a pretty successful webcomic site and Ive been having trouble trying to make some molds.

[MechanicalMashup]

I think plastic injection is a bit much. This is more a press mold like seen with the playdough or a pour mold. Keep in mind to there is a decent amount of shrinkage in these molds...

[EngineerJakit]

Now that i think about it, plastic injection for a flat-sided mold probably isnt something i should go for when it works better for a two-sided mold. Any ideas for making homemade liquid plastic? I think it might have to be done with some bags of small pellets you can find at a walmart's craft section.

[MechanicalMashup]

Use MEK and the mini pudding containers. Liquefy the containers in MEK and then pour into the mold.... (this is really really stinky so maybe consider www.smooth-on.com

[EngineerJakit]

2 things.

1. whats MEK?

2. think i could also use a plastic making method found here on instructibles?

http://www.instructables.com/id/Make-Potato-Plastic!/

Saw what this guy did! made some biodegradable plastic out of potato starch!

[MechanicalMashup]

MEK is Methyl ethyl ketone a very powerful solvent. You can get it at HomeDepot or a paint shop.

That plastic looks cool. Let us know how it goes

[EngineerJakit]

im gonna have to make a list of the materials ill need for this thing. I definitely know ill need corn starch! and maybe some spray paint.

[ilovegm]

What if I were to use lighter fluid to thin the silicone out?

[lizardlips75]

can i use this type of mold for hot sugar? i would like to make sugar bottles for a cake...

[bluebel95]

Can I use it to make Gummy candies? :)

[MechanicalMashup]

No the mold was made with solvents and non-food grade silicone so it would likely make you very sick

[Javin007]

This is pretty awesome! Is it possible to make one that doesn't have the 10-15% shrinkage?

[anarchy burger]

This is a brilliant 'ible, thanks so much for posting! i found that this stuff is MUCH easier to mix if you add the spirits (i've been using acetone) to the cornstarch first, then add in the silicone caulking; you can easily mix the mold mix with a spatula just like the one here . Would anyone happen to have any ideas as to how to make food-safe molds, such as different materials, curing processes, etc? And how well would this hold up in a 250-400*F oven?

[mikesnyd]

Ok so silicone is silicone. I think. So what if i took some High temp RTV silicone and did kinda the same thing. Would it hold most of the same temp properties? Allowing for higher melting point. i am in need of a gasket for my water heat transferer and when i puke the stuff straight out of the gun i have a hard time molding it to keep its form. due to the lengthy cure time of 24 hours. Not to mention it makes a skin in about 20min and still is gooey on the inside. even after a day if i make it any bigger then 1/2 inch it will split open and spit red silicone on me. And the stuff is like bear poop. Once touched it will transfer everywhere.

[MechanicalMashup]

Well the way it works is that silicone sets with water and corn starch absorbs water it draws water into the silicone to set it. So it should set faster. However how it changes the properties like the heat resistance I do not know...

[mikesnyd]

well if it just adding water to set the silicone then i hope my theory is right. That your thinning agent might need to be avoided so as not to have the shrinkage and possibly altering the temp resistance. I am making a batch today and have to find a hotplate to test it on. When i have more info i will post my findings. Thanks for your quick response. Oh and i am using a silicone that does not release formaldehyde when heated. Found a couple of high temps that do. And i do believe it is food safe.

[mikesnyd]

Did my test. Put my red cornstarch silicone onto a hotplate and i dont think it lost any or much of the properties. Mind you i didnt crank it to 400 deg F. Cause the wifey type needs her pancakes in the morning. And i like sleeping in the bed. I dont like the smell of the mineral spirits and the overall shrink factor with a 25% solution to thin.
As for the white gas. Naphtha or Kerosene fall into this category? And does the white gas have the same shrinkage? Maybe i will just use cornstarch and trim and sand for final sizing after all shrinkage has occurred.
Thanks again for this instructable. Never would have thought of adding a thickening agent to silicone.

[MechanicalMashup]

Well I definitely would not be putting white gas on a hot plate! The silicone alone with no thinner does not shrink. FYI

[mikesnyd]

well i was going to let the thinned silcone vent and degas for 1 week before testing it on a hot plate. Do you think it will still be flammable? I was wanting to pour my silicone into my mold for making my gasket instead of having to glob thick amounts in and hope for the best. but i just guess i will have to do what is safe. :(