Professional skin-friendly and biocompatible silicones In this category you will find platinum silicones that the manufacturer developed for skin contact, and silicones for which documentation on biocompatibility is available. They are used for prosthetics, podiatry, special effects, body casting, medical simulation and skin replication. ⚠️ Read what is actually claimed,...
Skin-friendly & Biocompatible Silicones (23)
Professional skin-friendly and biocompatible silicones
In this category you will find platinum silicones that the manufacturer developed for skin contact, and silicones for which documentation on biocompatibility is available. They are used for prosthetics, podiatry, special effects, body casting, medical simulation and skin replication.
⚠️ Read what is actually claimed, product by product
Skin-friendly and biocompatible are two different things, and not every product in this category meets both.
- ✓ Skin-friendly means the manufacturer considers the material suitable for contact with intact skin. Sometimes backed by its own testing, sometimes by a reasoned statement based on comparable materials.
- ✓ Biocompatible means testing has been carried out to a series such as ISO 10993. Note which part: 10993-5 is cytotoxicity, 10993-10 is sensitisation, 10993-23 is skin irritation. Those are not the same questions.
- ✓ Look above all at the contact category the testing was done for. A report is always drawn up for a specific tissue and a specific contact duration, for example intact skin for more than 30 days, or mucosa up to 24 hours. Outside that scope the report says nothing.
- ✓ A test report on the raw material does not automatically make your finished product safe. Pigment, softener, release agent, mix ratio, degree of cure and post-curing all shape the result.
- ✓ Read the specifications and claims on each product page, rather than relying on the name of this category. If you are unsure, or you need a specific document, contact us. CHT test reports and safety data sheets are supplied on request.
Background: USP Class VI, ISO 10993 and food contact, what those terms do and do not mean.
What is available per brand
Zhermack SFX 0020 and ZA SFX 10 WT 10, the only ones also assessed for mucosal contact
Zhermack has had two products evaluated to ISO 10993-1, and we stock both. The difference is in hardness and speed, not in the documentation.
- ✓ ZA SFX 0020, Shore 00-20, translucent, 1:1 by weight, 25 minutes working time, 1 hour 10 minutes cure, elongation at break 770 %. The softer of the two, for gel like appliances and skin replication.
- ✓ ZA SFX 10 WT 10, Shore A 10, translucent, 1:1 by weight, 12 minutes working time, 40 minutes cure, elongation at break 650 %, tear strength 14 N/mm. Firmer, holds its shape better and is ready much sooner. Can still be softened with Deadner.
The ISO 10993-1 evaluation covers two contact categories for both products:
- ✓ surface medical device, contact with intact skin, long-term contact of more than 30 days
- ✓ surface medical device, contact with mucosa, contact duration up to 24 hours
Endpoints tested: cytotoxicity to ISO 10993-5, sensitisation to ISO 10993-10 and skin irritation to ISO 10993-23. Result: no relevant biological effects. Study completed August 2023. Zhermack also states that no organic plasticisers are involved.
Note the scope. SFX 00-30 is not covered and has no biocompatibility report of its own. Neither does Zhermack SkinForm, a spreadable skin silicone for body casting and SFX moulds.
CHT True Skin, tested to ISO 10993-5 and 10993-10
True Skin 20 and True Skin 30, 1:1 mix ratio, developed for SFX and prosthetics.
- ✓ ISO 10993-5:2009 (cytotoxicity): tested at Pacific BioLabs. The materials were not considered to have a cytotoxic effect.
- ✓ ISO 10993-10:2010 (irritation and sensitisation): intracutaneous reactivity and the maximisation test for delayed-type hypersensitivity, both at Pacific BioLabs. No biologically significant irritation and no sensitisation reactions, in saline as well as in cottonseed oil.
- ✓ FDA 21 CFR 177.2600 compliance.
- ✓ For True Skin 30 a REACH SVHC statement and a RoHS 3 statement are also available.
The underlying CHT reports are supplied on request. This evaluation is aimed at skin contact and says nothing about mucosal contact.
CHT KÖRAFORM A 18, available soon
Coming to our range shortly. KÖRAFORM A 18 is an addition-curing casting silicone from CHT with a low hardness and high tear resistance. It is of interest in this category because in the properties list of its technical data sheet CHT writes, in as many words: “Certified for contact with skin and mucous membranes”.
What is not stated alongside it. The data sheet (edition March 2018) names no standard, no test institute and no report number with that sentence. It does not say by which method, by whom, for what contact duration or with what result the testing was carried out. We have requested the underlying documentation from CHT and will add it here as soon as we have it. Until then, treat the sentence as a manufacturer statement, not as a test report you can put in a safety file of your own.
- ✓ 1:1 mix ratio by weight, both components translucent
- ✓ Hardness Shore A 18-20 (DIN 53 505), tear propagation resistance 15 N/mm (ASTM D 624 form B)
- ✓ Mixed viscosity 9,000 mPa·s, density 1.08 g/cm³ (DIN 53 479)
- ✓ Pot life 4-6 minutes, demouldable after 20 minutes. A fast system, so have everything ready before you mix
- ✓ Tensile strength 3.5 N/mm² and elongation at break 400 % (DIN 53 504 S3A)
- ✓ Cures almost without shrinkage, and curing can be accelerated with heat
- ✓ Can be made thixotropic with KÖRAFORM TM, up to a maximum of 0.2 % by weight
Cured values measured after 14 days at standard climate DIN 50 014-23/50-2. Source: CHT technical data sheet KÖRAFORM A 18, edition March 2018. If you would like to be notified as soon as this product is available, please contact us.
CHT ALPA-SIL 40201, available soon
Coming to our range shortly. ALPA-SIL 40201 is a pourable, addition-curing two component silicone from CHT, 1:1 by weight. It is of interest in this category because in the properties list of its technical data sheet CHT states “Dermatologically tested”, alongside BfR Recommendation XV.
What is not stated alongside it. The data sheet (revision 1, 29 April 2021) names no standard, no test institute and no report number with that entry. We have requested the underlying documentation from CHT and will add it here as soon as we have it. Until then, treat the entry as a manufacturer statement.
Note the type of product as well. At Shore A 38-42 this is a mould making rubber, not an appliance material. Think of moulds and positives in prosthetics and SFX work, rather than casting the appliance itself. For work directly on the skin, True Skin, PlatSil Gel and the Zhermack SFX range remain the appropriate choice.
- ✓ 1:1 mix ratio by weight, both components translucent, transparent once cured
- ✓ Hardness Shore A 38-42 (DIN 53 505), elongation at break 400 % (ISO 37)
- ✓ Tensile strength 9 N/mm² and tear resistance 25 N/mm (BS ISO 34-1)
- ✓ Mixed viscosity 35,000 cP, cured density 1.0 g/cm³
- ✓ Pot life 13-18 minutes at 23 °C, demouldable after 45 minutes
- ✓ Linear shrinkage less than 0.1 %, and curing can be accelerated with heat
Source: CHT technical data sheet ALPA-SIL 40201, revision 1 of 29 April 2021. If you would like to be notified as soon as this product is available, please contact us.
Polytek PlatSil Gel
PlatSil Gel-10, Gel-25, Gel-OO, Gel-0020 and Gel-0030. This is the range most widely used in the prosthetics and lifecasting world for work directly on the skin.
Polytek has had these products independently assessed as skin safe under FHSA, ASTM D4236 and FDA requirements, and supplies the document Certified Skin Safe PlatSil Silicones with its technical bulletin. Both are available with the product.
What it does not say: this is a toxicological assessment for skin contact, not an ISO 10993 test series and not a statement about prolonged or permanent contact, about mucous membranes or about implantation.
Wacker Elastosil FX
Elastosil FX 10, FX 20, FX 28 and FX Gel 30, with the additives FX Fast, FX Slow, FX Thixo and FX Softener. Developed for special effects and skin applications. FX Gel 30 is the softest pourable grade in the range: Shore 00-30, elongation at break over 900 %, viscosity 4,000 mPa·s and demouldable after 45 minutes.
Wacker issues a Statement on Compatibility to Skin for FX 10, FX 20, FX 28 and FX Gel 30. It matters how that statement is built: no toxicological tests have been carried out on these products themselves. Wacker relies on ISO 10993 testing of comparable two-component addition-curing silicones and on the toxicological properties of the ingredients, and concludes that irritation or sensitisation is not expected on contact with intact skin. FX Softener has its own statement: it has not been tested either, but its addition is not expected to affect biocompatibility results.
About FX Softener: this is not an inert silicone oil. It is a reactive component, a monomer or very low crosslinking constituent, and it is incorporated into the network. There is an upper limit, however. Overdose it and the crosslink density drops so far that the material no longer cures properly and you are left with a larger extractable fraction. Stay within the dosage Wacker specifies and make test pieces. If you need softer than the softener allows, blend with a softer grade of the same chemistry rather than increasing the dosage.
⚠️ Wacker Silicones Health Care Policy, read this before choosing Wacker
Wacker's skin statements apply only if the end application falls within the WACKER SILICONES HEALTH CARE POLICY. That policy excludes a number of applications or handles them case by case:
- ✓ Contact with the genital mucosa is generally not permitted. Because silicone elastomers may contain significant amounts of silicone fluid, you must verify the conformity of the chosen Wacker product for that application with Wacker.
- ✓ Long-term applications of more than 30 days, single or repeated use, are generally excluded, with a case-by-case decision.
- ✓ Contraceptive and reproductive devices are assessed case by case.
- ✓ Breast implants and direct injection of silicone fluid into tissue or blood are not permitted.
- ✓ The customer must inform Wacker of any such intended use before purchasing.
If you are working on a product involving mucosal contact or prolonged body contact, contact us. We will put the application to Wacker, or recommend a brand to which this restriction does not apply. For mucosal contact up to 24 hours, Zhermack ZA SFX 0020 or ZA SFX 10 WT 10 is often the better documented alternative.
Products in this category that are for the mould, not for the skin
Elastosil Vario 15 and Vario 40 with Cat. Vario appear here because they are used in the same projects, usually for the mould into which a skin appliance is cast. Wacker states compliance with BfR XV and FDA 21 CFR 177.2600 for food contact for these products, plus declarations that phthalates, bisphenols, PVC, PFAS, SCCP, heavy metals, latex and fragrances, among others, are not intentionally introduced, that the product is not of animal or human origin, is not derived from GMOs and does not undergo irradiation. Compliance with the toy standards EN 71-3 and EN 71-9 and with CPSIA is also stated. Wacker's regulatory product information is available with the products.
That is explicitly not a skin safety or biocompatibility declaration. Cat. Vario additionally carries a platinum limit you must observe for food contact: 50 ppm under BfR XV, 150 ppm under FDA 21 CFR 175.300. The same applies to LSR Topcoat HE, which is a surface coating.
Do not confuse the ranges: the Wacker Elastosil M range is a mould-making range, not a medical range. Wacker's medical and pharmaceutical line is called Silpuran.
Typical applications
- ✓ Prostheses and orthoses
- ✓ Podiatry appliances and foot orthoses
- ✓ Special effects make-up and film prosthetics
- ✓ Body casting, skin replication and medical simulation models
- ✓ Animatronics, robotics and dolls
Correct processing counts as much as material choice
- ✓ Mix exactly by weight and stir slowly, right into the corners of the cup. A wrong ratio or a poorly stirred mix will not cure fully in places.
- ✓ Let it cure completely as stated in the TDS before you use or assess the product. Wacker places responsibility for suitable curing and post-curing conditions explicitly with the processor.
- ✓ Prevent cure inhibition. Sulphur bearing clay, latex gloves, PVC, uncured polyurethane and epoxy, cyanoacrylate and many SLA 3D prints can inhibit the cure of platinum silicone. See Poisoning of silicone (cure inhibition) and SLA 3D prints and platinum silicones.
- ✓ Consider post-curing for longer skin contact. It drives out residual volatiles and unreacted low molecular weight siloxanes and completes the network further.
- ✓ Everything you add belongs in your assessment: pigment, softener, release agent and any residue of it left on the surface.
For choosing the right softness: Shore hardness explained.
⚠️ Responsibility for the finished product
We, and virtually all suppliers, never certify that a product you make with silicones, pigments and additives is skin-friendly, food-safe or medical grade. Certifications apply to end products in their definitive form. Only then can the whole be tested and assessed. Every manufacturer statement in this category says so in as many words.
If you are making a medical device or a product with prolonged body contact, have the cured finished product tested by an accredited laboratory, as a rule to ISO 10993-5 and ISO 10993-10, together with a chemical screening. The information on this page is technical advice and not a conformity assessment.
Not sure which product fits your application?
Tell us what kind of contact it involves, for how long, and which documentation you need. We will then find out what exists and what does not. Email us at info@siliconesandmore.com.