Let me start this post by stating the obvious; I am by no means an expert at mould making or silicone in general. However, i have found it easy to work with and fairly affordable, all you need is a little patience and care when preparing for the pour to guarantee great results. I use a pourable “skin safe” silicone which is easily available online. If you are intending to use your mould to make personalised icecubes, chocolates or even as a baking mould you will need to buy food safe silicone. I buy all my supplies from either Aldax or directly from Barnes
What you will need.
- A protected workspace (there will be spills)
- Pourable silicone of your choice. I regularly use Barnes Pinkysil.
- 3 small measuring cups*
- At least 1 large plastic cup*
- A container big enough to hold your mould
- a craft knife
- oil based clay
- mixing stick
- the original object you want to mould.
*You may need larger or smaller cups depending on your method.
In this instance I am creating a mould to replicate a bangle that i have sculpted from oil based clay. This clay is easy to use, does NOT air dry and does not crumble. Preparation is key here. You must make sure that the item is as close to perfect as possible, any marks, dents and fingerprints will be replicated by the silicone. The picture of the bangle above was actually taken after i had removed it from the mould (guess who got so caught up in making the mould she forgot to take some pictures) and so it has a few marks on it from being pulled out of the silicone. I cant stress enough how important this step is. If your original isnt perfect neither will your cast be.
Step 1 - Preparation
Make a clay base to rest the item you want to mould on to. This clay base will form the top of the mould (we are working upside down here) and should be made as flat as possible. Once you have flattened it with your fingers (see picture) use a rolling pin covered in cling wrap to make it smoother. If there are small indentations in the clay you will need to remove them as it may let out some of the unset silicone.
Next place the item to mould on your base. If you want only a very thin opening in the top of your mold then place the item lightly on the clay. If your mould is for a flat backed object then you might like to press the item into the clay slightly, this will give you a cleaner edge and prevent the need to trim much later. When moulding for bangles i often put a small measuring cup in the middle to create a void. this will make my mould donut shaped but will save you money as you are not wasting silicone in the middle.
Place a container around the item to be moulded. Make sure the container leaves at least a centimetre in between the edge and the item to be moulded (if not the silicone will be too thin and will be more likely to split) Once you have measured that it is correct you will need use your craft knife to cut a hole in the container to allow the silicone to be poured into it.
Place the container back onto the item and push it into the clay slightly to seal the edges then wrap the excess clay over the the lip of the container to make it watertight. This step is very important, if you miss this you will find that the silicone will seep through and be wasted.
For larger items takeaway containers are great, for tiny items tealight candle foil containers work well.
Step 2 – Mixing
The silicone will most likely come in two parts, in two different colours. You can guess why this one is called Pinkysil. Measure equal parts of the silicone in your small measuring cups (these are disposable shot glasses)
At this point i will mention that you shouldnt worry about how much silicone you will need for your project too much. I always start with this amount. It will create at least two ring moulds and is usually enough for a small to medium bangle. The reason for this is that you can always mix up another batch of silicone after you have poured and found that you need more. Dont worry, unset silicone will stick to other silicone. It is better to do it this way than to waste excess product.
Pour both parts into a third (larger) cup and mix well. If you can see parts that are darker than others keep mixing, you want it to be a uniform colour to allow it to set properly. You will need to mix quickly, this stuff starts to set after a few minutes.
Step 3 – Pouring
Pour your silicone in an even thin stream into the mould making sure to get into as many spaces as possible. You may need to turn and tilt to get into all those spaces. Make sure that the silicone completely covers the item by at least a centimetre. If there are parts of your item peeking through mix up some additional silicone.
Once your container is filled with enough silicone you will need to wait patiently for a few minutes. You may see some bubbles come to the surface. You can blow on these gently and they will pop and form an even surface. You may need to use a drinking straw to get rid of bubbles in tight spaces.
Most silicones will not take long to set. I removed this mould from the container only half an hour after i poured it.
Step 4 – demoulding
After some time ( see the directions on your silicone) you will be able to remove the mould from the container. Start by removing the clay at the bottom. If you embedded the item into the clay it may pop out at this time, if you did not embed the object you have a couple more steps.
Use your craft knife to gently cut away at the little bits of silicone that have set around the lip of the container. Also gently cut the thin membrane of silicone that has formed over the surface of the object inside.
and out she comes.
Next you will need to remove the original item from inside the mould. Hard objects should pop right out. Clay objects need a little more care so that you dont leave half of it behind in there.
Tadah! here is your original one of a kind mould! It needs to be washed with warm soapy water to get out any clay residue and then trimmed of any excess silicone. .
Now its ready to be used over and over again to create replicas in different colours and patterns.