Using a liquid silicone mold maker

A couple of years ago, I created a tutorial showing you how to create a mold using the silicone putty mold maker. With the bases I created for the most recent round of Pure Art Collab, I knew the putty mold maker wouldn’t give me the flexibility I needed to cast them. I found Amazing Mold Rubber at my local Michaels earlier this year and bought it with the intention of trying it, and here it was, still sitting on my shelf!

If I wasn’t going to try it now, when would I?

Now that I’ve done a few, I thought it was time to share what I did to create these molds. I had a pretty successful turnout each time, and I think this mold maker is great for a beginner! While it was a little expensive (although silicone is), it was nice that I was just buying 8 ounces so I could get a feel for using it without wasting a huge amount.

Before I had cast my bases, I tested working with it by casting things I found around my apartment. This gave me a feel for the entire process and play with mixing and pouring the silicone.

Please note: This tutorial is simply meant to serve as a guide for starting with silicone mold making. We’re getting a feel for the process here, so we won’t be tackling more complex shapes like casting figurines and worrying about undercuts and things like that.

Supplies:

Please don’t be a Jessica; use safety equipment like gloves when dealing wtith resin and silicone. You don’t see me in the video, but I do use a mask made for chemical odors too.

To make the mold:

Before you start

If either your resin or silicone are measured out by weight, you’ll also need a scale. Some measure by volume (you’ll use the measuring cups), and others are by weight, so pay close attention to your instructions! In this case, both my silicone and resin measure out by volume, but I’ve used 2 part epoxy resin that is also done by weight.

Also, do not use anything silicone when you’re using silicone to make a mold. It will stick to itself, so if you use a silicone mixing cup or base, your mold or excess silicone will not peel off of it.

Making the mold

Step 1: Prepare your workspace

There are several different materials we could use as a base to pour our mold, but for me, the most readily available was wax paper. I like to rip off a longer piece to fold in half so that I can work on a double layer. This will not only give you space to protect your work surface, but the silicone and hot glue pull off of it very easily.

Now is also a good time to spritz the item you’re molding with mold release.

Step 2: Anchor the item you’ll mold

Once the mold release is dry, it’s time to anchor it to the wax paper. Use the hot glue to quickly cover the bottom of your item. My items were a little bigger, so I actually had a hard time covering the base with glue getting the base onto the wax paper before the glue solidified.

Step 3: Set up the barrier

Once your item is solidly in place, we’re going to place the cookie cutter around it. The item should be evenly spaced in the middle of your cookie cutter. Choose a size that is the smallest to fit around your item while still leaving 1/4″ all the way around.

Then we’ll want to hot glue the cookie cutter to the wax paper. Hold it firmly in place and aim the hot glue gun tip toward the seam where the cookie cutter meets the paper, and work it all the way around.

Now your mold set up is complete! We are ready to mix the silicone.

Step 4: Mix the silicone

Depending on what silicone you’re using, this stage will vary quite a bit. I’m using a silicone that requires to be measured out by volume, and it’s not a 1-to-1 ratio with the hardener.

There are formulas out there to help you figure out the amount of silicone you need to mix to most efficiently fill your mold. I ended up mixing in batches, mainly because the kind I used said it could be poured in layers if not enough was mixed. I erred on the side of not mixing up enough rather than mixing up a lot and wasting it.

For the silicone I had, every 2 oz. of base (the silicone came with 1 oz. measuring cups), 1 scoop of hardener was needed. Using this ratio, I mixed 4 to 6 oz. of base and 2 to 3 scoops of hardener.

I mixed up everything in a big paper cup so I’d have enough room for mixing. The silicone does not react to this material, so it was an easy way to mix it all together for a trial project.

Make sure to mix this extremely well. The length of time you can stir for will depend on your silicone. Mine didn’t have a super fast cure time, so I took 3 to 5 minutes stirring everything together and really combining the parts.

Step 5: Pour the silicone

When your silicone is mixed, hold your cup up above your project and begin pouring it into the casting area. Pouring from higher up will help trapped air bubbles make its way out of the silicone. It also helps to pour the silicone into the surrounding area instead of right onto your piece. Letting the silicone fill into the crevices of the item you’re molding will help make sure there won’t be air bubbles around your piece.

2 of my base molds had quite a bit of texture, and both of my molds successfully picked up everything without air bubbles since the silicone was allowed to fill in the gaps as the area was filling up.

Pour until your item is covered by at least 1/4″ of silicone.

Step 6: Wait for curing

Allow for the silicone to cure according to your silicone’s instructions.

Step 7: Remove from wax paper

Once your silicone is cured, you can pick up the mold and peel the wax paper from underneath it. The paper will most likely rip, so make sure you’ve removed all of the bits and pieces of paper from the bottom of your mold.

Then it’s time to peel off the hot glue around your cookie cutter!

Step 8: Ease out of cookie cutter

This is probably the hardest part of the process. The suction of the silicone and the cookie cutter make this step a little tricky, but just keep at it, and your mold should come out!

I found that if you pull the mold away from the edge (toward the middle of the mold) as you’re pushing it down, out of the mold, that helps release some of the tension and help it move easier. Work all the way around the mold, in several rounds, until the mold is released.

This part took me several minutes to do; you want to be careful not to rip your mold or break your original item in the process.

Step 9: Demold

This step is one of the more satisfying parts since you can see what your mold looks like!

Depending on how much silicone went under your item, you may have to remove a layer like I did. You can use an exacto knife to carefully cut through this layer all the way around.

Start peeling your silicone away from your item at the edges, working all the way around. You’ll hear and feel it peeling away from your item. Again, working slowly, keep moving further down the mold until all sides of your item have been released from the mold.

Then, start pulling the mold away from the bottom, working all the way around the item and then toward the middle. Keep doing this until the whole bottom has been peeled away from the mold.

Now, you should be able to ease your item out the of the mold and check your work!

Using the mold

Step 10: Prep your mold

With your mold finished, it’s time to use it! Spray more mold release into the mold and let it dry.

Step 11: Mix your resin

Mix up your 2-part resin according to your resin’s instructions. Mine is mixed in a 1-to-1 ratio using volume, so I poured to the same spot in 2 paper cups. Then, I poured 1 into the other and mixed for a couple of minutes before pouring it back into the other cup to pick up any remaining bits of liquid.

This will be where you’d add your colorant too. Be wary. Colorant can have a weird effect on how it cures if it’s not made by the same company that made the resin, so you may want to experiment first.

Step 12: Pour resin

You can now pour your resin into the mold. If you have lots of crevices, you may want to pour part of the resin in and then move your mold so the resin fills all of those spaces. Then you can resume the pour!

Step 14: Wait for curing

Allow for the resin to cure according to your resin’s instructions.

Step 15: Demold

Similar to how you unmolded your original item, you’ll work around the cast, pulling the silicone away from it until all the sides have been pulled away. The bottom will the last place you work the silicone before pulling the cast out completely.

I think the dye I chose to use for this last base didn’t react well with the resin. It cured just fine, but I had a really hard time getting this white base out of the mold, so enjoy watching my struggle .

Usually, pouring resin into molds requires some clean up. If you’re doing a more complicated, 2 part mold, you’ll have seams where the resin squeezed in between the 2 pieces of the mold. In my case, this resin was a little higher around the edges, so I had a sharp edge all the way around. I took care of this by using some wet-dry sand paper at 220, 320, and 400 grit to sand it down.

I’m not going to go into detail about this here in the blog post, because let’s face it, this post is long enough, but I wanted to give you a heads up!

This process is a pretty long one, but I think it was interesting to try creating bases in this manner. If I ever do a series that requires the same base, I will be sure to use this method so I don’t have to sculpt a new base each time.