Step 3: Mixing Oogoo

Picture of Mixing Oogoo
Mix By Volume
As stated before, Oogoo is simply a mixture of clear silicone caulk and corn starch. It can be mixed anywhere from 5 to 1 to 1 to 2 silicone to corn starch by volume. Up to a point, the more corn starch you add the faster it will set up. I like to mix it in small disposable cups using a Popsicle stick that is wrapped with Gorilla Tape to create a spatula. See pic4. Once it cures the Oogoo peels easily off the tape wrapped stick and the mixing/spreading stick can be reused.

Mix In Small Amounts
A good starting mixture to try out is 1 corn starch to 1 silicone by volume. It is easiest to mix it in small quantities so as to have plenty of time to work it. To see how it works, you could start with 1 tablespoon silicone caulk to 1 tablespoon of corn starch. You can reduce the amount to as little as 1/4 tablespoon corn starch to 1 tablespoon silicone if you want more time to cast it or sculpt it. I rarely mix up more than 3 tablespoons of silicone at a time.

The dry starch and sticky silicone do not want to easily mix. But if you are persistent and keep quickly stirring and mashing the mix, they will eventually merge into a thick paste. The resulting Oogoo is very sticky and will stick to anything that you spread it on. Most things it will stay well glued to. On a few things like some plastics and metals, it will easily peel off after it has cured.

The resulting Oogoo is a nice reflective white but I recommend coloring it so that you can easily see if you have an even mix. See the coloring step.

WARNING: While mixing, Oogoo will give off the strong smell of Acetic acid which can be irritating to the eyes and respiratory system. I strongly recommend that the mixing and forming be done outside or in a VERY WELL VENTILATED room. You should also wear nitrile gloves while mixing as the uncured silicone contains other solvents that might be absorbed by the skin.

One recurrent problem with silicone caulk is that once opened, it will tend to set up in the tube tip. To get a good seal I have had good luck using Gorilla tape wrapped over the tip. See pic4b. If you leave a quarter inch gap between the wrapped tape and the tip you can squeeze out just enough silicone to seal the tip well from air and moisture.

For sealing caulk tubes, I find sticking a large nail in the end of the tube works really well. Cheap, and reuseable, as long as you haven't cut the opening too large.
For those that would like a pourable version ...use 1-1-1 parts of
100% silicon caulk (white or clear)
Corn starch
Naptha or paint thinner....Naptha will set faster but costs is a little more.

I use this ratio to create molds to pour my fishing lures...like soft rubber worms..etc....it will stand heat up to 500 degrees.

Mix very well....NO LUMPS.....this ratio will start to set in 40 min...and be fully cured in 4-5 hrs....I let mine set for 24 hrs before i put them in full use.

How does the rubber compare to the putty version's?

f1dd13r1 year ago

I made some yesterday and managed to hang some pot lids up with it.

You can seal the caulk tube by removing the nozzle and laying some cling film/saran wrap over the hole, then screw the nozzle back on again to hold it there. Poke out the stuff stuck in the nozzle if there is any , so it can still be used.

I just seal the cartridge tube with a little of the silicone sealant, screw the nozzle back on, then put it back in the fridge.

JoelL32 months ago
Tyleriz6 months ago
mbelew1 year ago
To help with the vinegar smell you can water whip the silicone, this process can also be used to adjust the viscosity of silicone caulk. Squirt the caulk into an empty tub, pour some water in, stir it around vigorously (I use a metal kitchen whisk), pour the water back out. The caulk will thicken up quickly. If you need to, add a bit of toluene (common paint thinner/solvent) back in to thin it out a bit and extend the working time. It will still cure quickly, 10 minutes to harden, 24 hours to cure.

This process of water whipping the caulk is somewhat common in mold making for jewelry design. If I remember correctly my mentor added Talc based baby power as his "corn starch" equivalent when he needed to hand work the silicone. I think he used a powder that had Talc, Corn Starch and Sodium Bicarbonate as its ingredients. I know some of the molds he has made lasted 10 - 15 uses, and could last years.

I hope this helps someone.
So, does it have to be 100% silicone caulk? Also, does it have to be clear, or is that just your preference so you can dye it?
dinhoconrad2 years ago
Can I use this to make a custom earbud? Or is not ok to let this in contact with my skin?
siamonsez3 years ago
I was thinking about using this as a substitute got gel coat in my hot tub since I patched some problem areas recently and wasn't able to get the marine-tex stuff I used to go on smoothly in some of the funny shaped areas.
Does anyone have any idea about what would happen to it when underwater and exposed to the chlorine/bromine that will be in the watter?
Also, any suggestions on a mix that dries a bit harder and is easy to work with? I.e. spreading and shaping it?
lrdforster3 years ago
I was wondering if food dye wood work as a colourant. im not sure it would mix with the silicone before adding the corn starch but I am sure you can dye the corn starch before mixing but not sure the starch will dry the silicone as quick.

Any Comments? Has any one tried?
killbox3 years ago
Did a class At Quelab (our Maker/Hackerspace) with a variant of oogoo, coloring it with paint/makup/woodstain.

worked great for simple mold making. you can see some of our creations here

Okay, so I made a little sculpture with this BUT: I got it all over my hands and my comment is to help people remove this great goo from their skin. I used an orange oil cleaner as well as Dawn dish soap (original only - the one they use to clean up wildlife from the oil spills). It worked well, but I had to wipe off my gooey hands several times with paper towels (not so hot) and sacrifice a couple of microfiber towels.

I was, stupidly, thinking that the oogoo would just mold like a clay without fully mixing in the cornstarch.
you can handle it directly either by cornstarching your hands. or by dipping your hand's in some water. Water will accelerate its hardening, but i find the technique valuable for sculpting/smoothing/packing molds,

tinker2344 years ago
hi inthebathroom recomend me here i just want to know the consictcy for s human like skin
bpfh4 years ago
Do you have any idea on how much Oogoo shrinks when drying?

superpants4 years ago
I have been experimenting with something similar myself- mainly as I wanted to custom colour silicone. I have found that talcuum powder works well as a substitute for the cornstarch- I tend to mix a small amount of water with it and the colouring to form a paste, and then mix with the paste with the silicone. The key advantage of the talc is that it is in-organic so there will be no issue in the future with it supporting fungal or bacterial growth. Hope this helps some people!
AHHH!! I see someone else had the Talc idea! Good to see!
creekology4 years ago
I have been using this stuff for everything!

I found that a good way to mix it without having arguments between the starch and caulk is to have a non stick surface-I use an old laminated calendar-- and measure out your cornstarch onto it.
Pile thecornstarch into a little mountain then make a crater in the middle. Then put the desired amount of caulk in the crater , Powder your gloves with cornstarch and pull some from the edges of the crater over the top of the caulk. Use a light touch and proceed to fold and kneed the mixture as you
would bread dough. Keep pulling the cornstarch into it from the edges . If it begins to stick to your gloves, dip them in cornstarch again.
Pretty soon you will have a nice putty that you can pick up without it sticking to you. Then its ready to mold or shape.
I find a wood screw works best for cleaning out the tip of the caulk tube, if you dont use the caulk for a long period of time the caulk will eventually cure around the screw, but then all you have to do is grab it with some pliers and pull it out and it will pull the cured silicon plug out with it.
so, when you put in the silicone you have to wear nitrile gloves. do you have to wear them when youre doing stuff with the mixed oogoo? or does it cure when you mix it?
iklln64 years ago
with tubes like that i've always just jammed a 3" decking nail in the tube hole.

with the nail in place your caulking gun can sit indefinitely and the tube won't clog -- the nail will just take a little twist-pull action to get out.
Marcos iklln64 years ago
Ha! Been there, done that. It works over a short time (a few weeks), but much longer than that, the nail gets rusty, the caulk cures a little, and it's time to get out some Very Big Pliers, or Vise Grips to get the nail out. I've managed to pull the plastic tip right out of the caulking tube a couple of times.
DrPeper4 years ago
I've actually experimented with mixing Gorilla Glue and Silicone Sealant to see if I could get a result somewhere between the hardness of gorilla glue and the softness of silicone and it worked rather well. My first experiment was something around 2/3 silicone to 1/3 Gorilla Glue, it ended up on the softer side, closer to silicone, but definitely harder than just silicone. My next experiment I would like to do something more on the 50/50 side to see the results.

But my comment is that you could try adding Gorilla Glue directly into the mix to get something a little harder.

LOVE your Instructable BTW!