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Squishy Silicone (shore hardness 30-10) with 4 ingredients Answered

I owe my findings to the maker of "Oomoo" and community of hobbyists; thank you everybody! I needed squishy silicone, and the random knowledge I found here helped me with the puzzle pieces. The pink rectangle that you see in the pictures has the consistency of a gummy bear (shore hardness ~10). Grab: GE Silicone 1 caulk (or equivalent) Caulk Gun Odorless Mineral Spirits Baby Oil (Mineral oil) Acrylic Paint Sandwich zip baggies (medium large will help you) Cutting tool Mold negative (I use play doh because I only need basic shapes) Try to avoid glass... Don't use glass. A way to measure Tablespoons ADVISORY- your silicone (should) smell of vinegar and your mineral spirits will be potent of fumes.. and flammable. Use ventilation and protect your eyes. Your only saving grace is the baby oil scent. Okay. Grab the (new) silicone caulk and cut the whole pointy tip off of the tube, making a flush cylinder. Load that bad boy in the gun. Open a plastic baggie, and fill it with: 2 tbsp Mineral Spirits 1 tbsp Baby Oil (Mineral oil) Then shoot one full shot of silicone directly into the oily puddle of liquid. Close the baggie, leaving a little air. Find a way to mix it. I lay the bag on a smooth table and repeatedly iron the baggie with my pinky. You have 20+ minutes pot time, so be thorough. You should now have a clear 'spit' like liquid that runs, similar the two liquids you just mixed. Open the bag. Add: 1 drop acrylic/oil paint Close it, and repeat the mixing until your color is even throughout the liquid. Turn your baggie sideways and cut a small triangle from one of the bottom corners. Carefully tilt the bag like an icing baster and pour the silicone into your mold negative. This method is clean and offers control. You can squeeze ALL of your mix into the pour, as well as combat air bubbles. Don't touch it for 3 hours. Better yet, leave it for three days. It takes this long for the shrinkage to happen. You can avoid shrinkage if you use xylene instead of mineral spirits, but it is not available to me. The color will become opaque in this time as well. You now have very squishy silicone. I have tried many other pours and I can't manage to get the cured squishy consistency without mixing a liquid to start. A goop is preferable to me because I can use it a caulk, still, allowing me to 'draw' silicone positives. To achieve a shore hardness of ~30 Repeat the steps above, but now use: 1 tbsp Mineral Spirits 1 tbsp Baby Oil (mineral spirits) This will have an initially 'goopier' mix, and you will have similar pot/cure time, but no shrinkage. It will be oily until you repeatedly dry it. The picture of four silicone squares illustrates my last advice. Each mix has only one drop of the same pink acrylic paint. You may want to experiment with how much color you want. Far Left: the gummy bear mix 2:1 softest Inner Left: the hardness 30 mix 1:1 Inner Right: FAILURE did not cure (1/2 tbsp baby oil, 1tbsp mineral spirits) Far Right: FAILURE did not cure (2 tbsp baby oil, 1 tbsp mineral spirits) toughest The two squares on the right could have been made with just silicone, mineral spirits and NO baby oil. Maybe, add ~3 drops of glycerin and I could have had the same hardness AND a thurough cure, but I want the squishy. Hopefully this helps.

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VRPlanesWalker
VRPlanesWalker

6 weeks ago

UPDATE- concerning the gummy bear mix- I realized that adding 1/2 tbsp of corn starch to the mix (AFTER combining the first 4 ingredients) will make for a better result. The cure will keep the gummy consistency, while becoming immediately opaque and oil free, as well as soft. This will half your pot/cure time once added. Lastly, you can keep a soft exterior by occasionally powdering the silicone with cornstarch- much like with seamless dolls. Please play around with the mixtures! I would love to see what others have come up with.

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Jack A Lopez
Jack A Lopez

6 weeks ago

I knew about the use of a drop of acrylic paint (aka emulsion paint), for to evenly distribute catalytic amounts water, to make sure all the silicone cures.

Mixing in a plastic bag is an improvement I had not seen before. As you say, "This method is clean and offers control. You can squeeze ALL of your mix into the pour, as well as combat air bubbles."

Those are some good looking blocks of cured elastomer!

Thank you for sharing this.

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VRPlanesWalker
VRPlanesWalker

Reply 6 weeks ago

You are very welcome!