Mold Making with Liquid Silicone

Mold Making with Liquid Silicone

Hey guys! This short tutorial of how to make flexible silicone molds was a big source of inspiration to format my website. I hope my descriptions and instructions are clear enough for you, and if not please don’t hesistate to comment below asking for clarification or other questions. Happy mold making, yo!

Clicking on the pictures will direct you to a new page with an enlarged version of my image.

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Materials

What do we need (What I used):

  • Liquid silicone (2 pounds Copyflex Liquid Silicone)
  • Objects for the mold shape:
    • Plastic/glass gems (Clear aquarium stones)
    • Oven-bake or sculpting clay (Sculpey)
  • Flat bottomed and sided container for mold (Plastic lunch container)
  • One or two flat bottomed and sided mixing containers (Old movie popcorn buckets)
  • Flat-edged mixing stick (Clean popsicle stick or plastic ruler)
  • Measuring scale (Mechanical food/kitchen scale from local drug store)
  • Butter knife (Random metal knife from kitchen)
  • Optional: Water/containers for measuring sufficient liquid volume needed
  • Optional: Calculator
  • Optional: Glue + small paint brush for glue application on bottom of mold objects
  • Optional: Small scissors or makeup scissors for triming off silicone that creeped under your shape during curing
Some of your materials will differ depending on the type of liquid silicone you use. My Copyflex is food safe, so I am able to use and reuse any kitchen items involved after a good wash.
Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Measuring Silicone

1) How much liquid silicone will you need?

Method 1

a. Place objects you wish to make a mold of in the mold container.

b. Fill container with water until the water is at least ¼ inch above the highest point of your objects. This water represents the ounces you need (total) for the silicone.

c. Divide this number by 2 to get the ounces required from both silicone parts, A and B (assuming you are using a 1:1 silicone compound, which makes measurement a hellofalot easier).

 Note: Do not use water to calculate the weight/pounds of silicone you need because water and silicone do not have the same liquid density and mass.

Method 2

a. Your liquid silicone supplier should provide calculations for determining the quantity you need. If none are provided, use the calculation I used to measure for my CopyFlex compounds (found on makeyourownmolds.com/copy-flex).

L” x W” x H” (thickness of  mold container) = cm³ (cubic inches) of the liquid silicone that you will need.

b. Multiply this number .70 to find the weight in ounces.

Note: Calculate the pounds you need to order for your project by determining dividing this number by 16 to calculate the silicone in pounds.

This calculation and measurement step is the hardest part, but don’t worry. Just make sure you have enough silicone and we’ll come back to it after we do stuff with the objects we want to mold. 

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Mold Objects

2) Mold or find the shapes of the object(s) you wish to make a mold of! For my shapes I used oven-bake clay for specific shapes and sizes, and other little gemstones for smaller shapes I used to fill in the space between my bigger shapes.

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

3) Paint a thin layer of Elmer’s glue to the bottom of each shape to keep it in place and put it in the mold container. The glue helps keep silicone from sliding underneath the object, and make sure to wipe away any glue that squishes out the sides so it doesn’t mess with the mold’s outline.

Optional: You can put a non-stick wax on your shapes if you want, but it’s not necessary. It could warp the outcome of your mold if not applied evenly, but I was able to remove my clay/glass objects with no problem. It is silicone, after all, once cured it easily peels off.

Preparing the Pour

 4) Measure your silicone on an electric or mechanical kitchen scale and mix it together really well in an appropriately sized container. I used a ruler for mixing because it has flat sides and you need flat sides of your mixing utensil in order to make sure you aren’t missing any unmixed compounds on the sides of your container.

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Note: Sometimes the instructions call for mixing the silicone in two different containers to make sure both components are mixed thoroughly, but I don’t think this step is necessary if you did a good job mixing.

 5) MIX ‘ER UP REAL GOOD NOW.

Optional: If you have a really detailed shape you’re making the mold of, paint a thin layer of liquid silicone on the surface of the object. Make sure you get your brush into all the details of the object air bubbles are not trapped in any crevices and compromising the accuracy of your mold.

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Pouring the Silicone

6) Time to pour! Do what the pros call a “stretch pour” by pouring in one spot 12” above the to-be-mold. This way, the air bubbles we created during mixing are eliminated as the silicone stretches while pouring. You will actually see the little air bubbles stretch and break as they fall off the edge of your mixing container.

7) Start your pouring in one corner of the mold box and let the silicone ooze across the surface. Sllloowwwlyyy move across the mold box while stretch pouring on the liquid silicone. Do not pour directly on your object just in case an air bubble gets trapped on your mold object and accidently disfigures the shape of the mold.

Curing Process

8) Wait your liquid silicone supplier’s designated cure time so the mold has time to moldify. CopyFlex cures in four hours, but I preferred to just come back to it the next day. The cure time will depend on the temperature in your workspace and how much you poured, so since my house can be as cold as a meat locker wanted to give my stuff more time. When working with silicone, it is usually preferable that your house is around room temperature.

9) How do you know the silicone is cured? The silicone will not imprint if you touch its surface. My Copyflex mold was not as squishy as I expected but it looked perfect!

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Removing the Mold

Don’t rush removing your mold from its container, this is a slow but cool process.

10) Gently pull at the edges of your mold where your silicone meets the plastic container. Pull at the edges all around the container, slowly loosening the top half. Once you’re back where you started, use a slim, flat object like a butter knife to wedge and unstick the mold from each side, use your best judgement to gently pull the silicone sides up.

Make sure you distribute the “unsticking” process equal for all sides of the container. The mold should pop out fairly easily from its plastic container.

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

11) Congrats you have a mold!

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Note: You may notice that some silicone trickled under your mold object during cure time, but no worries because the excess silicone can easily be cut away with makeup or craft scissors. The smaller and more accurate a blade, the better of course!

Hopefully you found this tutorial helpful, and it clarifies the process of making a mold with liquid silicone. This was my first time making a mold, and if I forgot to mention anything/you want extra information just let me know! Good luck in your own project :) you can do it!

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

Liquid Silicone Mold Making Tutorial by Oshley Cosplay

 

 

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