Silicone used to be a material that was available only to major manufacturing industries. The invention of room-temperature vulcanizing (RTV) silicone has allowed artists and hobbyists to use the material as well. Silicone objects are typically poured into molds, which can be anything from specialized prototype molds to candy molds. Even a cupcake pan can serve as a mold. Silicone is typically measured by weight or volume and it is very important that you follow the right procedure for the right kind of silicone.
Things You'll Need
Paste wax (optional)
Paper towels (optional)
Hand soap (optional)
Spray mold release
Silicone base and catalyst
Preparing the Mold
Clean any dirt or residue from previous castings out of the mold.
Brush a thin coat of paste wax into molds made out of porous materials such as plaster or wood. Buff out the excess wax with a paper towel.
Brush a thin coat of hand soap into molds made of silicone. Allow it to dry, then buff out the excess.
Spray two thin coats of silicone mold release into the mold, allowing each to dry completely.
Measuring by Weight
Place a measuring cup on a scale.
Reset the scale to 0 with the cup in place. This takes the weight of the cup out of your measurements.
Pour silicone base, sometimes called Part A, into the cup and record the weight.
Calculate the amount of catalyst, sometimes called Part B, to add. The instructions on the silicone will tell you how much to use. For example, if the ratio is 10:1 and you have 100 ounces of base, you need 10 ounces of catalyst.
Add the proper amount of catalyst to the base, stopping when the scale reaches the correct combined weight. In the previous example, you would stop at 110 ounces.
Mix the silicone and catalyst thoroughly using a craft or paint stick. Scrape the sides and bottom of the cup several times to ensure complete mixing.
Slowly pour the silicone into the mold from as high as you can. Any air bubbles in the silicone will break as it drizzles down.
Allow the silicone to cure for the time given in the instructions. Some silicones cure in as little as 30 minutes, while others require 24 hours or more.
Remove the object from the mold.
Measuring by Volume
Pour the silicone base into a graduated measuring bucket. Note how much you have added.
Calculate how much of the catalyst you must add to a second bucket. Silicones that are measured by volume often have a ratio of 1:1, 1:2 or 2:1.
Measure the proper amount of catalyst into the second bucket.
Pour the catalyst into the silicone base and mix it thoroughly.
Pour the catalyzed silicone into the mold from as high as you can.
Allow the silicone to cure and remove it from the mold.
Silicone molds are great for making decorative food items. Make a silicone mold of a small object that you want to replicate, and you can shape cookies, butter, gelatin, ice or any other malleable food item with it.
If you want to paint your silicone, be sure to use a latex or oil-based paint for the most effective results.
Do not use platinum silicone in a mold made of tin silicone. It will not cure, resulting in a sticky mess. If you are unsure what kind of silicone your mold is made of, don't risk casting platinum silicone into it.