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Food-grade, skin-friendly and medical silicone
Food-safe, skin-friendly and medical silicones
What do USP Class VI, ISO 10993, FDA and food contact actually mean? And which silicone do you choose for a mould or product that touches food, skin or the body? A practical guide to making the right choice, plus an honest picture of who is responsible for what.
Why silicones are used so widely
In many applications silicones are considered relatively safe. They are often biocompatible, oxygen-permeable and, once cured, generally contain no large amounts of harmful substances. That is why you find silicones in products that touch food, in contact lenses, implants, prostheses and even in dressings for scar tissue.
One thing to know up front: not every silicone is suitable for every purpose. Whether an end product truly meets the requirements for food or skin contact depends both on the material and on the way you process it. This page explains both sides.
The two main types of silicone
Chemically, we divide silicone rubbers into two groups. That distinction largely determines whether a silicone is suitable for food, skin or medical use.
1. Condensation-cure silicones
These silicones cure with a catalyst based on tin (or tin compounds). They come as:
- a ready-to-use 1-component sealant (the familiar silicone sealant), or
- a 2-component system (RTV-2).
Condensation silicones are mainly used for moulds in art and industry that do not come into contact with food. Most are not suitable for food contact. The reason: the curing reaction continues slowly, so the material keeps releasing residual products. In addition, the raw materials used are generally less pure than those in addition silicones. There are a few exceptions, such as Wacker E41 and E43.
2. Addition-cure silicones
These cure with a platinum or peroxide catalyst. They come in three forms:
- RTV-2 (platinum): a 2-component set that cures at room temperature. Widely used by craftspeople, hobbyists and smaller businesses for which the high investment of an LSR injection machine is not viable.
- LSR (platinum, injection): a 2-component set processed under pressure by injection machines. Less fluid than RTV-2, but considerably stronger. Often used for food-grade, baby-safe and sanitary products.
- HTV (peroxide or platinum): 1-component high-temperature vulcanising silicones. Used for food-grade moulds and other strong end products.
Important: only some addition silicones qualify as food-safe, skin- and medically compatible. Virtually no condensation silicone (category 1) does. Addition silicones with a peroxide catalyst must always be post-cured, and sometimes a scavenger must be added to remove residues of peroxide or acid, before it is meaningful to have the product tested.
The standards explained: USP Class VI, ISO 10993, FDA and food contact
Customers often ask about these abbreviations. Below is a short, concrete summary of what they mean, so you know which standard is relevant for your application. Note: food contact and biocompatibility are two separate tracks. A silicone that is skin-friendly or USP Class VI is not automatically suitable for food contact, and vice versa.
USP Class VI
A US biocompatibility standard (United States Pharmacopeia, chapter <88>). The strictest of the USP classes. The tests are carried out on material samples: systemic toxicity, an intracutaneous (under-the-skin) reaction and an implantation test. Frequently requested for medical and pharmaceutical applications, but it is a material test, not an approval of your end product.
ISO 10993
The international standard for the biological evaluation of medical devices and the relevant standard for the European market. ISO 10993 does not assess the bare material but the end product in its final form, including processing and sterilisation method. More extensive and more differentiated than USP Class VI.
FDA (United States)
For silicones in food contact, 21 CFR 177.2600 is the relevant section ("Rubber articles intended for repeated use"). The FDA does not approve silicones; a manufacturer declares that the material meets the conditions set out there. So "FDA approved" does not exist in this context, whereas "complies with 21 CFR 177.2600" does.
Food contact (Europe)
The framework is Regulation (EC) 1935/2004, article 3. Silicones are exempt from Regulation (EU) 10/2011 (which covers plastics), and as a starting material they fall outside 2023/2006. In practice manufacturers assess against the German BfR Recommendation XV (Silicones), with a typical limit of max. 0.5% volatiles in the cured elastomer. France (Arrêté of 25-11-1992) and Spain additionally set a migration limit of 10 mg/dm² or 60 mg/kg.
The most common misunderstanding
USP Class VI and ISO 10993 do not say the same thing. USP Class VI is tested on the material, ISO 10993 assesses the end product in its actual use form. So "our material is USP Class VI" is a statement about the raw material and not a certificate for what you make with it. The same silicone tube can be biocompatible in one product and not in another, depending on sterilisation method, contact duration and the other components. A material that passes USP Class VI usually also meets many of the requirements of ISO 10993, but the reverse does not apply automatically.
The same goes for food contact: a manufacturer's declaration concerns the raw material. Whether your mould complies in practice depends on processing, post-curing, additives and cleaning.
Which silicone do you choose for what?
| Application | Recommended type | Note |
|---|---|---|
| Mould for art or industry (no food or skin contact) | Condensation RTV-2 or addition RTV-2 (platinum) | Most affordable route; no food/skin requirements needed |
| Mould for food (chocolate, sugar, ice) | Food-safe addition silicones & HTV | Post-cure as prescribed; processing determines the result |
| Skin contact / body casting / prosthetic work | Skin-friendly & biocompatible silicones or lifecasting silicones | Platinum, not condensation; mind skin sensitivity |
| Medical or series end product | LSR and HTV silicones | The end product itself must be tested and certified |
Who is responsible for what?
We, and most suppliers, never certify that a product you make with silicones, colourants and other additives is food-safe, skin-friendly or of medical quality. This is not unwillingness but a logical consequence of how these certifications work.
However clean and safe the raw materials are, certifications apply only to end products. A product is only assessed and certified once it has been formulated clean and non-toxic, processed with suitable equipment in an appropriate environment (often a cleanroom), fully cured and post-cured, packaged correctly and reliably sterilised. Only then can the whole be tested and approved.
On the basis of the above, Silicones and More accepts no liability for the outcome of tests, nor for the success or failure of a project. We supply the materials with the best available information; the processing and certification of the end product are your responsibility.
How to approach a food-grade or medical product
Products in our webshop that carry the added note "food-safe" or "skin-friendly" generally meet, on their own, the relevant FDA and BfR requirements that apply to that product. Provided they are processed correctly, they are therefore unlikely to be the cause of any rejection of your end product. The route looks like this:
- Choose a silicone labelled FDA, food grade or skin-friendly.
- Ask us for the manufacturer's Regulatory Product Information (PCS), so you have the exact declaration and its limitations in writing.
- Process it exactly as prescribed, and do the same with all your other ingredients.
- Ensure quality control, suitable packaging and, where needed, sterilisation.
- Have the end product tested by an expert, independent third party.
- Does it fail? Find the bottleneck, adjust the process or ingredients and test again.
This route costs time and money, but the result is entirely yours and cannot simply be copied. It gives you an edge with customers who prefer certified products.
A recurring effort
A tested and certified product line requires maintenance. Assess quality regularly, keep your process accurate and repeatable (which often requires ISO standards) and have external tests carried out periodically. If you change your material, processing or sterilisation, biocompatibility must be reassessed.
Frequently asked questions
Is a food-grade silicone automatically suitable for medical use?
No. Food grade and medical are different requirements with different tests. Medical use generally requires biocompatibility testing such as USP Class VI or ISO 10993 on the end product.
Is a skin-friendly or biocompatible silicone automatically food-safe?
No, and this is a common mistake. Biocompatibility (USP Class VI, ISO 10993) and food contact (1935/2004, BfR XV, 21 CFR 177.2600) are separate assessments with their own tests and their own limits. Some silicones meet both, many meet only one of the two. Always check the manufacturer's declaration for the specific product.
Which documents can I request from you?
For most brands we can supply the manufacturer's Regulatory Product Information (also called PCS or Product Compliance Statement). It states, per product, what applies for food contact (1935/2004, BfR XV, 21 CFR), allergens, heavy metals, RoHS and BSE/TSE, including the associated limitations. We also supply the TDS and the safety data sheet (SDS).
Why is condensation silicone usually not food-safe?
The curing reaction continues slowly, so the material keeps releasing residual products. The raw materials are also generally less pure than those in addition silicones.
What is the difference between USP Class VI and ISO 10993?
USP Class VI assesses the material with three strict in-vivo tests and is mainly used in the US. ISO 10993 is the European standard and assesses the end product in its actual use form, including processing and sterilisation. ISO 10993 is more extensive and more differentiated.
Do I need to post-cure addition silicones?
For many food-grade and medical applications post-curing is required, and for peroxide-catalysed silicones almost always. Post-curing removes volatile residues, which matters directly for the BfR limit of max. 0.5% volatiles. Follow the time and temperature stated in the TDS of the product concerned. With peroxide systems a scavenger may be needed to remove peroxide or acid residues.
Not sure about the right choice?
Need help choosing the right silicone for a food, skin or medical application? We are happy to think along with you about material choice and processing.
Get in touchThis information is intended as general guidance and does not constitute a guarantee or certification. The suitability of an end product for food contact, skin contact or medical use must always be established on the final product, tested by a qualified independent company. Always check the current TDS, SDS and product specifications.