How to Make Silicone Molds to Create Flatback Resin Pieces

Make your own silicone molds with 8 quick and easy steps


You can always opt to purchase silicone molds to make amazing resin pieces, as there are numerous to choose from. However, if you’re looking to save and explore unique shapes and styles, then it’s always great to know how to make your own silicone molds for both your flatback, and non-flatback pieces.

Making your own silicone mold is not as complicated as it may sound, additionally it gives you the opportunity as the artist to be as inventive as you can with the type of pieces you create. In this article you’ll be taught how to create your own silicone molds, so you can cast and make multiple versions of your pieces. 

There are many ways to make molds, however the method in this article is quite easy, quick and less messy. In this instructional a silicone mold will be created using a few flatback teacups.

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Step 1:  Positioning your originals

To begin, lay out and line up four of the original flatback pieces that you wish to create the silicone molds for, on a grid map. In this case four flatback teacups. This will give you an idea as to how big your mold should be.

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Step 2:  Building blocks box mold

The next step is to use a few building blocks from your kid’s toy box, and use that to create a custom mold box. If these are not at your disposal, you can use other items to hold the liquid such as: cookie cutters, plastic cups and tupperware. You can even make your own by using cardboard, foam board or plastic sheets.

The building blocks however are a quick and easier solution as you can create any size that you want, without the risk of wasting silicone. It’s also reusable and space saving since you do not have to have different size mold boxes all over.

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Continue to stack on more building blocks until you achieve the perfect height around your teacups or other. Also ensure that you have a quarter inch space between the mold box and the originals to minimize the risk of the mold tearing.

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Step 3:  Silicone measurements

Now it's time to figure out how much silicone you’ll be needing. To figure this out, pour some rice in the mold box with the originals inside. Make sure that you also cover the top of the teacups or other at least a quarter inch.


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Once you’ve done that, pour that rice in a measuring cup to see the volume. As a recommendation, mix slightly more silicone than what you measured to account for the silicone that will remain in the mixing cup. In general when pouring out your silicone you do not want to scrape off the cup, this is to avoid any unmixed parts in your mold.

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Step 4:  Securing your originals and mold box

Moving forward you will need to secure your originals and mold box in place. To do this, use self laminating sheets, and cut a piece that is bigger than the mold box. Laminating sheets are preferred over contact paper because the adhesive is stronger.

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When you’ve cut the desired size laminating sheet, place your four teacups onto the sheet and then add your mold box. To secure them in place even more, gently hold and move the mold box, with the sheet over the surface of the grid map, or press the sheet firmly onto the base of the mold box with your fingers or resin spatula. 

You do not need to use any hot glue with this as the walls are thick enough, and the silicone's thick viscosity wont allow it to leak out, however there may be some seepage.

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If you are worried about leakage, you can always fold the laminating sheet over the side walls. 

However if you are using any other kind of mold boxes, you will most likely need to use hot glue, but you will have to skip the laminating sheet and secure your originals and the mold box on a non-porous surface... This is because the heat from the glue will distort the laminating sheet.

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Step 5:  Mixing the silicone

As a caution remember to always use platinum cure silicone when working with resin. Do NOT use tin cure silicone as this type will cause the resin to not cure properly.

It’s now time to mix and add your silicone. Different brands will have their own measurements, so read the instructions carefully. In this article the ratio for the brand used is a 1 to 1 ratio, which can be measured by volume or weight. However, using weight provides you with much more accuracy.  

Like resin, two parts silicone also has a pot life or working time once the parts are mixed, this can be 10 mins or more depending on the brand. 

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When mixing the silicone it may be difficult to see if it’s properly mixed, so make sure to mix for about 5 minutes and scrape the cup.

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Step 6:  Vacuum chamber

If you are adding color to your silicone to make custom colored molds, you may not need to worry about potential bubbles that may be in  your silicone. However, if you want bubble free silicone, you may need to place it in a vacuum chamber. You can find affordable vacuum chambers online if you do not own one.

Just to note, if the brand of the silicone you’re using states that vacuuming is not necessary, then you can always skip this step. Usually low viscosity silicone doesn’t often need this process.

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Any liquid you place under a vacuum will expand, so ensure that the container you’re using is large and tall enough to deal with a lot of overspills. You want to then turn on the vacuum and use it for about 3 to 5 minutes. 

One tip is to release the vacuum and turn it back on and then repeat the process throughout the 2 to 5 minutes, this helps to pop the surface bubbles.

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Step 7:  Adding the silicone

When the silicone is all done, it’s now time to add it to your box mold. Since the silicone doesn’t produce large bubbles, there’s no need to pour it in a small stream at a high point. However, you may need to use a toothpick to move any bubbles that form in the nooks and crannies of your original.

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Remember not to scrape the silicone off the cup to avoid the unmixed parts in the mold. Once you’re through adding your silicone, leave it for about 12 - 24 hrs to cure.

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Step 8:  Removing the silicone mold

After the curing time has ended, it’s time to release your silicone mold from the mold box and remove the originals.

All you have to do is peel back the laminating sheet and remove the building blocks. On your silicone mold you may see a few straggly ends from where the silicone may have seeped, just simply take your scissors and remove them.

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And that’s it, you now have your own silicone mold made by you. 

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You can go right ahead and try to use fast curing resin to test out your new mold, or get started on creating some more new and exciting silicone molds.

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