Prosthetics - How to run silicone prosthetics!

Creating the prosthetics is arguably one of the more exciting steps in this entire process. After spending so long designing, sculpting and moulding, the actual piece can now be made ready to use.

As with any mould, it is important to make sure it has been released. This could be using products like Eject-It spray, or even petroleum jelly. There needs to be a decent layer applied, to ensure the appliance doesn't get stuck and have a higher chance of tearing, but it doesn't need to be swimming in release agent. If too much is applied, it could mix with other products and affect how well the piece comes out.

Once released, an encapsulator can be applied. If this is a two-part mould (snap mould), this encapsulator needs to be applied to both parts, as does the releasing agent. The encapsulator used is a thin, plastic/vinyl material, also known as Cap-plastic. This had been more commonly used to create bald caps, but in recent years, had become part of the prosthetic creating process. (Bray, S. 2020). The purpose of the encapsulator is to give the prosthetic a surface that makeup can stick to. Prosthetic silicones are rather sticky after they have set, which makes it very difficult to apply makeup to or even apply adhesives. (Bray, S. 2020). Applying this to both parts of the mould ensures the front and back of the piece will have this layer.

There are two main versions of this cap-plastic, alcohol based and acetone based. Alcohol and acetone are both solvents used to thin the cap-plastic, and also to blend it away during the prosthetic application process. 

Figure 1 - Acetone Cap-plastic (Neillsmaterials, no date)

Figure 2 - Alcohol Cap-plastic (Neillsmaterials, no date)

Using these appears to be personal preference. As the alcohol based requires 99% isopropyl alcohol, this could cause an issue down the line if alcohol palettes would be used for detailing. These palettes, such as Skin Illustrator, also require 99% alcohol to work. This could result in the encapsulator blending away while applying the makeup. This risk is reduced if acetone based is used, however this can be very harsh and drying on the skin.

The mixing ratio for both of these encapsulators is 1:3. That is 1 part cap-plastic, to 3 parts solvent. This can then be brushed into the mould in 3 thin layers, making sure each layer has set before starting the next. Once complete, a pin can be used to gently pick up an edge to check the thickness. According to Stuart Bray, you will know the layers are thick enough as there won't be any obvious holes. (Bray, S. 2014). An alternative method to applying cap-plastic is to use an airbrush. This requires a higher ratio of solvent, to ensure the encapsulator is thin enough to be atomised. As is it much thinner, more layers are required, around 5 or 6. The pin test can be performed multiple times to check, with more layers being applied if needed.

Figure 3 - Pin test on cap-plastic (Bray, S. 2014)

In Stuart Bray's video, he states that his mixing ratio is 1:4 for airbrushing. This could depend on the brand of product or the airbrush he had used, however when the student had attempted this method, the ideal ratio was 1:7, which was upped to 1:8 as that was still too thick to pass through the airbrush.

Next is to fill the mould with prosthetic silicone. Like the cap-plastic, there are different options to choose from. A common silicone is PlatSil gel 10. This is a "1:1 mix, fast curing silicone that can be used for making moulds and props, masks and, with the addition of deadener, create silicone gel prosthetics" (Neillsmaterials, no date). This silicone has a shore scale of A10, making it the hardness of a rubber band. A deadener is added to this mixture to soften the silicone even further. For platsil gel 10, Smiths Deadener is ideal. According to Mouldlife, this silicone can require a lot of deadener. "On average if using Smiths Deadener, 150% - 200% may be required". (Mouldlife, no date). This percentage is worked out by knowing the total weight of part A and B together. For example, part A and B will be 10g each, making an overall 20g batch of silicone. 20g = 100%. If 150% of deadener is required, this would be 30g of deadener added to the mixture. 20g(100%) / 2 = 10g(50%). 20g(100%) + 10g(50%) = 30g(150%). 20g(100% silicone) + 30g(150% deadener) = 50g This results in a 50g batch overall.

Figure 4 - Polytek Platsil gel 10 (Polytek, no date)

Figure 5 - Polytek Smith's Deadener (Mouldlife, no date)

An alternative silicone is Platsil gel 25. This has a shore scale of A25, a hardness roughly between a rubber band and a pencil rubber. This can be used for mould making as well as prosthetics. This product seems to be a lot more versatile, allowing the product to start at A25, and be softened all the way to 00035 (similar to a gel shoe insert). LV Deadener is used for this mixture. When used in prosthetics, a minimum of 100% deadener should be used so that it has a higher chance of adhering to the cap-plastic.

Figure 6 - Polytek Platsil gel 25 (Polytek, no date)

Figure 7 - Polytek LV Deadener (Polytek, no date)

These silicones are typically clear, however they can be coloured prior to running the prosthetic. This requires specific silicone pigments. These can come in flesh tones, as well as many other colours. Pre-colouring can help later on with makeup as it can give you a desired base colour to work on top of, or the colours can be applied in a way to reduce the amount of makeup needed.

Figure 8 - Example of a pre-coloured prosthetic (Hellman, J. no date)

Figure 9 - Flesh coloured wound prosthetic (Hellman, J. no date)

For example, in figure 9, different coloured silicone could have been sponged into the mould to add details or give a base colour. A yellow colour could have been placed in the areas of the adipose tissue, then deepened up with makeup later on, whereas makeup would currently have be applied over the entire surface. 

Another way to detail or colour prosthetic silicone is to add flocking. Flocking is made of short, monofilament fibres, typically used to add fur or hair details in character makeup looks. 

Figure 10 - Flocking being applied with a flocking gun (Minke-props, no date)

Flocking is added into silicone prosthetics as skin isn't just one colour. It often has hints of yellow, red and even blue. Flocking is very effective in adding this detail.

Figure 11 - Silicone piece with flocking (Titanicfx, no date)

After planning out the piece, deciding the colouring and flocking, and preparing the mould with cap-plastic, an appliance can be created. Pigments and flocking should be added to the silicone prior to mixing, as most have around 5 minutes of working time before they begin to set. After mixing throughly, the batch can be sponged or poured into the mould from height and in a small stream to release any air bubbles. If using a snap mould, the silicone should only be poured where the piece is, as to avoid it getting stuck in the cutting edge. The positive cast can be squashed tightly into the negative with the use of clamps. For flat moulds, once the silicone has been poured, a straight-edged utensil, such as a wooden craft stick, can be used scrape off the excess silicone, ensuring no silicone is on the cutting edge of the piece. 

Figure 12 - Example of scraping off excess silicone on a flat mould (Bray, S. 2014)

After allowing the silicone to cure, flat moulds require more layers on the back to encapsulate fully. This should be done the exact same way as the first set of layers (i.e. if 3 layers were brushed on initially, another 3 layers should be brushed onto the back). Talcum powder can be generously applied after the final layer of cap-plastic has set, and the piece can be de-moulded. This should be done very slowly as not to tear it, with talc being applied during the process. The talc is applied as the cap-plastic may stick to itself and could potentially ruin the piece, so the powder takes away this stickiness. 

Figure 13 - Applying talc before de-moulding (Bray, S. 2021)

Figure 14 - De-moulding the flat mould (Bray, S. 2021)

When de-moulding a snap mould, talc can be brushed into any gaps around the edges. Chisels and a rubber mallet can be used to separate the positive from the negative. This should be done carefully as not to damage the mould or the piece. One chisel can be propped into one end of the mould, with a second opposite. This can help to get better leverage and release the suction that is keeping the pieces together.

Figure 15 - Releasing the suction with two chisels (Brown, J. 2021)

These moulds were marked to indicate where the cutting edge of the piece was, as some areas were very close to the edge of the mould. This was to make sure it wasn't accidentally damaged.

Figure 16 - Marking where the cutting edge is close to the edge of the mould (Brown, J. 2021)

Figure 17 - Markings seen when mould is squashed (Brown, J. 2021)

As the two parts separate, the positive should be gently lifted out, with plenty of talc being applied as the encapsulator releases from it. An edge can be lifted from inside the negative mould and slowly released, with the same method as the flat mould and a lot of talc powder. 

Figure 18 - Positive removed, prosthetic piece still inside negative mould (Brown, J. 2021)

A silicone prosthetic piece should now have been created. The snap moulds do have a bit of a learning curve, figuring out the correct amount amount of silicone to use and getting the squash tight enough so that the silicone is pushed out of the cutting edge. The more attempts and practice, the better the results will be. 

Snap mould trial and errors can be found here.

Flat mould trial and errors can be found here.

-Jess

References:

• Bray, S. (2014) How To Use Flat Moulds by Stuart Bray. Available from https://www.youtube.com/watch?v=O1U7XFSiCh8&ab_channel=stuartbraystuartbray [Accessed 13/05/2021].
• Bray, S. (2020) Cap Plastic & Airbrushing. Available from https://www.youtube.com/watch?v=A71eYQF-Ot4&t=227s&ab_channel=stuartbraystuartbray [Accessed 13/05/2021].
• Platsil Gel 00 & 10 Guide. (no date) Available from https://www.mouldlife.net/platsil-gel-00--10-guide-300-c.asp [Accessed 13/05/2021].
• Platsil Gel 10. (no date) Available from https://www.neillsmaterials.co.uk/product/platsil-gel-10/ [Accessed 13/05/2021]. 

Bibliography:

• Debreceni, T. (2019) Special makeup effects for stage and screen: Making and applying prosthetics. 3rd ed. Abingdon, Routledge.
• Encapsulator. (no date) Available from https://www.mouldlife.net/encapsulator-118-c.asp [Accessed 13/05/2021].
• Flock and the flocking process. (no date) Available from https://www.swicofil.com/consult/industrial-applications/para-textil-and-carpets/flock [Accessed 13/05/2021].
• Flocking 100ml pot (7gm). (no date) Available from https://www.neillsmaterials.co.uk/product/flocking-100ml-pot-7gm/ [Accessed 13/05/2021].
• PlatSil Gel 0025. (no date) Available from https://www.neillsmaterials.co.uk/product/platsil-gel-0020/ [Accessed 13/05/2021].
• PlatSil Gel 25. (no date) Available from https://www.neillsmaterials.co.uk/product/platsil-gel-25/ [Accessed 15/05/2021].
• PlatSil Gel 25 Deadener LV. (no date) Available from https://www.mouldlife.net/platsil-gel-25-deadener-lv-3678-p.asp [Accessed 15/05/2021].
• Silicone Prosthetics: Casting A Silicone Prosthetic. (2014) Available from https://www.youtube.com/watch?v=JDVktVIxHl0&ab_channel=BrickInTheYardMoldSupply [Accessed 13/05/2021].

Figures:

• Figure 1 - Key-Cap Plastic. (no date) Available from https://www.neillsmaterials.co.uk/product/key-cap-plastic/ [Accessed 13/05/2021].
• Figure 2 - Super Cap Plastic. (no date) Available from https://www.neillsmaterials.co.uk/product/super-cap-plastic/ [Accessed 13/05/2021].
• Figure 3 - Bray, S. (2014) Available from https://www.youtube.com/watch?v=O1U7XFSiCh8&ab_channel=stuartbraystuartbray [Accessed 13/05/2021].
• Figure 4 - PlatSil Gel-10. (no date) Available from https://polytek.com/products/platsil-gel-10 [Accessed 13/05/2021].
• Figure 5 - Smiths Prosthetic Deadener. (no date) Available from https://www.mouldlife.net/smiths-prosthetic-deadener-2324-p.asp [Accessed 13/05/2021].
• Figure 6 - PlatSil Gel-25. (no date) Available from https://polytek.com/products/platsil-gel-25 [Accessed 15/05/2021].
• Figure 7 - PlatSil Deadener LV. (no date) Available from https://polytek.com/products/platsil-deadener-lv [Accessed 15/05/2021].
• Figure 8 - Hellman, J. (no date) Mutant Facial Markings / Silicone Prosthetic / X-Men / Mystique / Cosplay / LARP / Latex Free / Marvel / Halloween / Comic Con / SFX makeup. Available from https://www.etsy.com/uk/listing/673725845/mutant-facial-markings-silicone?ref=shop_home_recs_48&frs=1 [Accessed 15/05/2021].
• Figure 9 - Hellman, J. (no date) Large Wound / Silicone Prosthetic / Halloween / Latex Free / Special effects makeup / LARP / Zombie / Gore / Blood / SFX. Available from https://www.etsy.com/uk/listing/578849251/large-wound-silicone-prosthetic?ref=shop_home_recs_54&frs=1 [Accessed 15/05/2021].
• Figure 10 - SKINNER flocking gun. (no date) Available from http://minke-props.com/en/product_info.php?info=p388_skinner-flocking-gun.html [Accessed 15/05/2021].
• Figure 11 - Titanic FX Flocking- Green. (no date) Available from https://titanicfx.com/products/titanic-fx-flocking-green [Accessed 15/05/2021].
• Figure 12, 13, 14 - Bray, S. (2014) How To Use A Flat Mould by Stuart Bray. Available from https://www.youtube.com/watch?v=O1U7XFSiCh8&ab_channel=stuartbraystuartbray [Accessed 15/05/2021].
• Figure 15, 16, 17, 18 - Brown, J. (2021) Leeds.