How To Make A Silicone Mould In 8 Simple Steps
One of the questions I often get asked is "Where do you buy your silicone moulds from?" Well, the answer is, I don't buy them, I make my own.
As I've become more adept working with Jesmonite, I've found myself limited by the silicone moulds available on the marketplace. When you first start out learning a new craft, there are so many elements to master at once, mixing, colour, colour palettes etc. However, once you have found a nice groove, some of these elements that are trickier early on become second nature and you can start exploring more ways you can improve your craft.
A lot of the commercial moulds available are quite popular now and are used by a lot of other creatives. Wanting to break out from the mould (pun very much intended), I decided it was time to create my own designs that are unique and bespoke to me, designs that no one else has.
If you're feeling similar limitations and want to create your own moulds, this simple 8 step guide is here to help! Please note, this is the best practices I have found when working with silicone, I strongly advise you do your own experiments and research to discover improved ways of working.
What You'll Need
A mixing cup
A mixing stick
A template to mould
A housing for your template
A Stanley knife
A level surface
(Optional) A cocktail stick
1. Create your template
To begin, you'll firstly need something to mould. I strongly advise you create this yourself, whether it be constructed from wood, metal, polymer clay, or even 3D printed. The template you intend to mould needs to be firm and solid.
Silicone is incredible at replicating minute surface details (such as woodgrain or surface imperfections), so depending on your desired look, you can either keep the raw material or sand and fill it in to create a smooth, clean surface.
Here is an example of the incense dish template I designed and built. Like many of my designs, I start with two yoghurt pots, pour Jesmonite into the negative space and work it up from there.
I strongly advise that you do not use found objects as a template, as these may be subject to copywrite infringement. I do not object to using these objects as a tester while you learn how to use silicone, but they should not form part of your final craft if you plan to sell them.
2. Create a housing and stick down your template
You will need to find a house for your template that is larger than the shape you are moulding. Depending on the size and shape of your template, I recommend that the housing should create thick walls to support the shape, but also thin enough that you can still bend and manipulate the silicone when it comes to removing it from the mould.
You need to ensure that your template is really stuck onto your housing, otherwise, silicone can creep below and detach your template.
Try to use a reusable container for housing. Ice cream tubs, yoghurt pots and Tupperware boxes are great for this kind of job and can be used time and time again to create more moulds.
In this example I am using a medium sized ice cream tub. I have stuck my incense dish template onto the base. The thick gap between the incense dish and the walls of the tub means my silicone should be firm enough to support the final shape of the incense dish.
Remember, everything is upside down when it comes to making moulds, so double check your template is stuck the correct way up.
3. Mix your silicone
This is the fun part, mixing your silicone is straightforward. I like to use a pigmented silicone as it's easier to see when the mixture if fully combined.
You'll need to follow the mixing instructions from your silicone, it usually involves taking a thick gloopy agent and mixing it with a catalyst. The chemical reaction between these two ingredients is what will cause the gloopy silicone to set.
How much silicone to mix requires a bit of guess work. It is worth noting that silicone takes hours to set, so if you don't make enough to cover your template initially, simply mix more and continue to pour it on top.
4. Pour your silicone over your template
Pouring from a height will reduce the amount of air bubbles within your silicone. Lift your mixing pot up high and allow a slow trickle of silicone to pour out onto your template.
You'll want to make sure the entirety of your template is covered, going beyond the height of your template to make sure the base of your final mould will have enough thickness.
Leave your mixing cup to one side to cure. Once the excess silicone has cured on the cup, you can easily (and very satisfyingly!) remove it.
5. Place on a level surface and leave to cure
Place your silicone template onto a level surface to cure. It is important the surface is level to ensure any future pieces you cast with that mould are also level.
Gently tap the sides of your housing to bring any additional air bubbles to the surface. You may also notice some micro-bubbles which you can pop with your mixing stick or a cocktail stick.
Depending on the silicone you have used, it will need several hours to cure. The silicone I use is set within 5 hours, however, I usually leave it a full 24 hours to ensure it's solid.
6. Remove your silicone mould from the housing
When it comes to removing your mould, you will initially want to score along the edges to release any suction from the sides. I start by carefully scoring with a Stanley knife then sticking an old butter knife along and levering underneath. Depending on the size of the item you've moulded, this should provide you with enough room to put your fingers underneath and pull out the mould.
If your design is stuck and you're struggling to remove it, you can of course destroy the housing, it just means you won't be able to reuse it again later.
You now have a silicone mould which should accurately represent the template you just moulded!
7. Tidy up your mould
If your template was not stuck down correctly to the housing, you may find that you have stray silicone which has seeped underneath. You can cut away at any excess silicone with your Stanley knife.
8. Start using your mould!
Congratulations! You made a mould! Silicone is so fun to work with and can create so many more opportunities and designs.
All of my terrazzo pieces have been cast in silicone moulds which I have made. As I work exclusively with terrazzo designs, I need to sand Jesmonite in order to reveal the terrazzo beneath the surface. This allows me greater flexibility with the integrity of my moulds.
If you'd like to see some of my terrazzo designs which I've casted from my own moulds, they are available on my Etsy shop!