silicon to make a mould

[tartarine]

Hi

I was wondering if someone could recommend a good compoud to make a silicon mould.

Obtainable in Europe if possible

I need to make a mould, then a plaster cast of a scroll.

My idea is make a silicon muld

open it up

take of course the original out and fill with plaster

any suggestion ?

thank you in advance

[La Folia]

Silicone

This is silicone:  https://en.wikipedia.org/wiki/Silicone

This is silicon:  https://en.wikipedia.org/wiki/Silicon

[Davide Sora]

47 minutes ago, La Folia said:

Silicone

This is silicone:  https://en.wikipedia.org/wiki/Silicone

This is silicon:  https://en.wikipedia.org/wiki/Silicon

Yep. 

I assume the OP is referring to silicone rubber for making casts.

[tartarine]

of course 

any suggestion ?

 

 

[FiddleDoug]

Make sure you put some kind of mold release on the scroll when you do it.

[Don Noon]

No specific suggestions from me, but googling "silicone for mold making" will get a lot of results.

[LCF]

7 hours ago, FiddleDoug said:

Make sure you put some kind of mold release on the scroll when you do it.

Yup.

 

Also test the mold release first to make sure it doen't either soak in or cause finish problems. Best ones are volatile sprays. 

[LCF]

Pinkysil is useful because it sets quickly. Make sure also that your cask is watertight ie the mold case. Seal it with beeswax.  Uncured silicone casting rubber leaks through very small gaps. 

[tartarine]

On 5/13/2026 at 10:12 PM, Don Noon said:

No specific suggestions from me, but googling "silicone for mold making" will get a lot of results.

yes but none of the results will tell me which does not shrink when dry

[Don Noon]

53 minutes ago, tartarine said:

yes but none of the results will tell me which does not shrink when dry

With the wonders of asking AI, you get a lot of info (I do not personally vouch for any of this):

For zero shrinkage in mold making, platinum-cure liquid silicone is the industry standard. These high-performance, two-part silicones offer negligible (often \(0\%\)) linear shrinkage, ensuring your casts maintain exact dimensions over multiple uses. [1, 2, 3, 4]

Top-rated non-shrinking silicone options for mold making include:

• LET'S RESIN 10A / 0A: An extra-soft, highly elastic liquid silicone known for extremely low shrinkage and a bubble-free pour. It has a 1:1 mix ratio by weight and is ideal for intricate crafts, resins, and wax. Check the Let's Resin 10A Liquid Silicone Rubber for detailed specs.
• Smooth-On Mold Star Series: A popular platinum silicone that cures to a strong, tear-resistant rubber with excellent long-term library life and practically zero shrinkage. You can explore options on the Smooth-On Mold Star Series page.
• R PRO 10: A toxic-free, addition-cure silicone boasting a \(0\%\) linear shrinkage rate. It's highly stable, mixes easily 1:1 by volume or weight, and is available on Amazon.
• TAP Platinum Silicone: An ultra-low viscosity silicone that self-degasses and provides professional-grade dimensional stability. Learn more via TAP Plastics. [1, 2, 3, 4, 5]

To ensure your mold doesn't shrink and cures perfectly, keep these tips in mind:

• Platinum vs. Tin Cure: Always opt for platinum-cure silicones over tin-cure formulas. While tin-cure is cheaper, it is prone to slight shrinking as it ages.
• Avoid Cure Inhibition: Platinum silicones can fail to cure (remain sticky) if they come into contact with sulfur-based clays, UV resins, or 3D-printed photopolymer resins. Use sealants like clear acrylic spray on suspicious master models before pouring.
• Proportions: Always measure Part A and Part B exactly as directed (usually by weight, using a digital scale), as altering the ratio can affect the integrity and shrinkage rate of the rubber. [1, 2, 3, 4, 5]

To help me recommend the perfect silicone for your specific project, tell me:

• What are you casting in the mold? (e.g., epoxy resin, wax, soap, concrete?)
• Does your master model have deep undercuts or require a brush-on versus pourable block mold?

[LCF]

I have not found much shrinkage in pinkysil or smooth-on two part silicones. They have two equal A and B parts -  I think these are plat cure? I don't like the types with bulk silicone but small amounts of liquid hardener because the hardener is very toxic and stinks. 

 

There are processes to follow, things to know. The best information I have come across online is this man, Robert Tolone.

 

 

 

i suggest you watch as many of his videos as you can.

 

 

[LCF]

Smooth on is that blue one. All of the silucones are available in different durometers.

 

I've used these 2 mostly:

Pinkysil Fast Setting Silicone Rubber - Skin Safe & Easy to Use
https://www.barnes.com.au/product/pinkysil-fast-set-silicone/?srsltid=AfmBOopMjeBCxNhk3lzuLp579M6CP61HaSvEUjFjfXbA2uc1l1rUkksd

Pinkysil is 'certified suitable for skin contact'

 

SiliCreate Liquid Silicone Rubber Mould Making Kit - 1:1 Mix - 1Kg/2Kg/4Kg/10Kg | eBay Australia https://www.ebay.com.au/itm/353033007580

 

 

[tartarine]

thank you for your answers

I will have a go :-))

[tartarine]

On 5/28/2026 at 11:28 PM, Don Noon said:

With the wonders of asking AI, you get a lot of info (I do not personally vouch for any of this):

For zero shrinkage in mold making, platinum-cure liquid silicone is the industry standard. These high-performance, two-part silicones offer negligible (often \(0\%\)) linear shrinkage, ensuring your casts maintain exact dimensions over multiple uses. [1, 2, 3, 4]

Top-rated non-shrinking silicone options for mold making include:

• LET'S RESIN 10A / 0A: An extra-soft, highly elastic liquid silicone known for extremely low shrinkage and a bubble-free pour. It has a 1:1 mix ratio by weight and is ideal for intricate crafts, resins, and wax. Check the Let's Resin 10A Liquid Silicone Rubber for detailed specs.
• Smooth-On Mold Star Series: A popular platinum silicone that cures to a strong, tear-resistant rubber with excellent long-term library life and practically zero shrinkage. You can explore options on the Smooth-On Mold Star Series page.
• R PRO 10: A toxic-free, addition-cure silicone boasting a \(0\%\) linear shrinkage rate. It's highly stable, mixes easily 1:1 by volume or weight, and is available on Amazon.
• TAP Platinum Silicone: An ultra-low viscosity silicone that self-degasses and provides professional-grade dimensional stability. Learn more via TAP Plastics. [1, 2, 3, 4, 5]

To ensure your mold doesn't shrink and cures perfectly, keep these tips in mind:

• Platinum vs. Tin Cure: Always opt for platinum-cure silicones over tin-cure formulas. While tin-cure is cheaper, it is prone to slight shrinking as it ages.
• Avoid Cure Inhibition: Platinum silicones can fail to cure (remain sticky) if they come into contact with sulfur-based clays, UV resins, or 3D-printed photopolymer resins. Use sealants like clear acrylic spray on suspicious master models before pouring.
• Proportions: Always measure Part A and Part B exactly as directed (usually by weight, using a digital scale), as altering the ratio can affect the integrity and shrinkage rate of the rubber. [1, 2, 3, 4, 5]

 

To help me recommend the perfect silicone for your specific project, tell me:

• What are you casting in the mold? (e.g., epoxy resin, wax, soap, concrete?)
• Does your master model have deep undercuts or require a brush-on versus pourable block mold?

I will make a plaster cast with dental plaster moldano