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How to Upcycle and Reuse Silicone to Create More Silicone Moulds

As a mould maker, it's fair to say that I use a reasonable amount of silicone. Whether it's building new designs, improving existing designs or scaling up the number of moulds I have for each cast; silicone is an essential part of my workflow.


With that in mind, occasionally I'll make a mould that doesn't quite work how I expected. While that's a shame, the main concern is - what are we supposed to do with all that wasted silicone?


Well, fear not! In my recent post, I discussed a method to upcycle unwanted silicone and reuse it to make another mould. So, how did it turn out?


Let me tell you. It worked exceptionally well.


The Process

To recap the process, following this tutorial video from Jonathan Shaller, it requires you to take your unwanted moulds, chop them up into smaller chunks and then process them through a meat grinder.

Bucket filled with large chunks of sliced pink silicone
It's recommended you clean your silicone and your utensils before starting this process - though I am a very messy artist, I found this thin layer of dust did not impede the final results

The larger chunks of silicone are then placed into a grinder to produce finely ground pieces. These finer chunks can then be combined into fresh silicone to bulk out the mixture and poured over your template. From here you continue as you would when making any other mould.

Bucket filled with ground pieces of pink silicone
I used a meat grinder to reduce the larger chunks to smaller pieces

If you've never made your own mould before, you can read up on the full process on my post How To Make A Silicone Mould In 8 Simple Steps.


The Findings

When combining my chunkies with my mixture, I was adamant this was never going to work.


I trailed a mixing ratio of 1:1. While this did indeed work, my second attempt of 60% fresh silicone to 40% chunkies was much more manageable to work with.

The 1:1 ratio was thick and stiff. It was difficult to mix and even harder to pour over my template. I casted a photo stand; this is a slender parallelogram shape with a thin slit in the centre used to insert your photo. You can see the final outcome further into the post.

A pot of purple silicone, freshly mixed and not yet cured
Pure freshly mixed silicone is silky smooth and runny
Pot of freshly mixed silicone with added chunks of reused silicone
Adding the chunkies to the silicone mix bulks out the mixture and makes it increasingly more difficult to stir
3D printed template of a photo stand next to a pile of upcycled silicone
The mould in question is for a Photo Stand, which features a thin slit down the centre where photographs can be inserted

Surely there was no way this thick, chunky silicone was going to nuzzle its way into that thin groove?


But, if you don't try, you don't learn. So I poured my 1:1 mixture into the mould and whipped up a second batch at 60% fresh : 40% chunkies. This was much more workable and far less labour intensive to mix.

Left: 1:1 ratio mix, Right 2:3

After pouring my silicone over my template, I usually spend 10-15 minutes tapping and vibrating the piece to remove any air bubbles. This process was not enjoyable with the 1:1 mix. The base of the piece is bumpy and uneven, which would cause some concerns when a project requires you to create completely level moulds.


The 2:3 mixture was far more viscous, the chunks did not settle on the top and that provided me with a flat, level base for my mould.


The Results

Initially, I was so certain this method wasn't going to work for me - surely my mixture was too thick and it would leave large gaps in my mould? How wrong I was!

While the bottom of the piece is bumpy and there are small flecks of dust and dirt throughout, I honestly don't think you could tell this mould is made with 50% recycled silicone chunks.


It's flawless. In fact, both moulds turned out flawlessly.


On closer inspection, you can see these long thin laminations on my mould - these imperfections are supposed to be there as they are impressions from the original 3d printed model.


Yes, my original mould template is not flawless but as I always sand back my material to reveal the terrazzo patterns beneath the surface, I don't need my mould templates to be smooth.


If anything, this amplifies how well the 1:1 chunkies ratio still managed to replicate the surface details of my mould. This is a process I will continue to do going forward - there will be no more wasted silicone on my watch!

Close up of a pink silicone mould demonstrating the laminations on the surface
The lines in my mould are intentional as they are present within the 3d printed template I originally moulded

These recycled moulds behave just as well as my other moulds made from 100% fresh silicone. You can see from the image of the final Photo Stand below that there are no obvious imperfections as a result of using a recycled mould.


If you'd like to see the other designs I have made with this mould, they are available on my Etsy.

Black and white photo stand with a tarot card in the centre

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