Reusing Silicone Molds & Saving Money




Introduction: Reusing Silicone Molds & Saving Money

About: Some people can work on one project at a time. Not me.

If you've ever purchased mold-making silicone in a gallon size or larger, you realize how expensive this stuff can be. While it's amazing and worth every penny, I've been looking for ways to reuse the silicone and save some cash. I've heard of people grinding it up or sticking extra pieces in the top of a mold, but I want to share with you the method that I've found to be quite effective.

*** Please note that if you use a mold release, this method will likely not work. ***

So let's save some money, and cut up some old silicone molds!

Step 1: Cutting Up Old Silicone Molds

We're going to cut up old silicone molds into pieces that can be stacked inside our mold box. You'll want to cut up the silicone in different shapes depending on the shape of the piece you're molding. For me, I was working on a new prop - Chirrut Îmwe's staff (from Star Wars Rogue One) - and my mold box was narrow and very tall.

So using some kitchen shears, or even better for the thick areas, sheet metal shears, I cut an old prop mold into long thin strips.

Once you get the mold cut into strips (and get a blister in the process), you're ready to start stacking the pieces inside the box, like a Tetris pro! I've put together some illustrations on the following step.

Step 2: Stack the Pieces

Since it's difficult to tell much of anything from the top of my mold box, I decided to 3D illustrate how this works with one side cut away from the mold box.

In the first illustration, you'll a render of one side of my Rey Staff Prop. As the images progress, you'll see how I stack the pieces of silicone. Since the silicone is made to pick up every detail in the prop you've created, the silicone should easily travel down into each of these cracks. Once you run out of old silicone to stack or you get to the top, you're ready to start pouring in the new silicone.

So let's pour some silicone!

Step 3: Pour the New Silicone

When it comes to pouring new silicone, I choose to work in steps, tilting the box from side to side, to free up any bubbles that might have been trapped under the prop edges or the old silicone pieces. Depending on the size and shape of your mold box, this may not be necessary.

Using this method, I was able to drastically reduce the amount of new silicone needed, and I was able to save a considerable amount of money in the process of building a new prop mold.


Have you tried it, or is there a different method that works better for you? Let me know in the comments!

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    1 year ago

    If you have mold release on your molds, you can remove it by washing the silicone to be reused with mineral spirits or acetone. I usually use each sequentially followed by dish soap (usually dawn) and water when I want things really clean, as it needs to be here. Keep in mind the life of these molds may be shorter due to the old mold material separating from the new siicone over time. This could probability be prevented by using a silicone primer.


    5 years ago

    I understand how this saves you silicone, but I don't understand how you get your prop out of the mold. Every mold I have done is either in two halves, or it has an access port on top to pull out the prop.


    Reply 1 year ago

    Or you can use a very stretchy silicone like dragon skin. I don't recommend doing this if you are reusing old molds as done here. That just encourages delamination between new and old silicone.


    Reply 5 years ago

    Hey, RoguePirin! I'm using the easy mold method where you pour the mold then open it up with a cut along one side, usually with a curvy line. This way, you don't get registrations, but you don't have to fool with pouring each side individually.