Chavant Hard is the high-hardness professional oil-based clay for precision modelling, presented in 906 g blocks in green. Its completely sulphur-free formulation makes it fully compatible with both platinum and tin silicones, eliminating any risk of inhibition when pouring directly onto the original. If you need a material that holds up to tools, CNC milling or moderate workshop heat without deforming or losing detail, this is the reference.
Technical specifications
| Property |
Value |
| Format |
906 g block |
| Colour |
Green |
| Hardness |
High |
| Sulphur-free |
Yes |
| Approx. melting temperature |
85 °C |
| Toxicity |
Non-toxic, dust-free |
| Reusable |
Yes |
| Compatible with platinum silicones |
Yes |
| Compatible with tin silicones |
Yes |
What it is used for
Chavant Hard is designed for work where detail retention and dimensional stability are the priority. Its high hardness makes it especially suitable for modelling with metal tools, CNC milling and 3D scanning, as it withstands tool contact without accidental marks or deformation. Being sulphur-free, you can pour platinum silicone directly onto the original without any additional precautions.
- Sculpting originals for moulding with platinum or tin silicone
- Industrial prototyping and product design
- Character, creature and FX piece modelling
- CNC milling and machining on oil-based clay
- 3D scanning of hand-sculpted originals
- Architectural models and high-precision technical pieces
- Creation of prosthetics and FX pieces to be moulded with platinum silicone
How to use it
- Soften the material: Chavant Hard is firm at room temperature. Warm it gradually with a heat gun, in a low-temperature oven (do not exceed 85 °C) or under an infrared lamp until workable. Do not heat it suddenly or in a microwave.
- Knead and condition: Once soft, work the clay with your hands or with modelling tools to even out the temperature and eliminate internal air pockets.
- Sculpt the original: Sculpt with metal tools, punches or spatulas. The high hardness allows clean edges and fine details without fingers or tools accidentally sinking into the material.
- Refine the surface: To smooth, apply localised heat with the heat gun or use a little isopropyl alcohol 99.9 % with a brush to smooth without altering the volume.
- Check for contaminants: Being sulphur-free, you can pour platinum silicone directly onto the original without a prior sealer. Make sure there are no other inhibiting materials on the same piece.
- Mould the original: Apply your chosen platinum silicone following the manufacturer's instructions. Chavant Hard does not adhere to silicone, which makes demoulding easy.
- Recover leftover material: The clay is 100 % reusable. Collect the offcuts, warm them up and reincorporate them into the main block.
Usage tips
Working temperature control
Chavant Hard is formulated for workshop environments that may reach moderate temperatures. If the workshop is very warm in summer, store the block somewhere cool so it maintains its characteristic hardness. Conversely, in winter or cold workshops, you will need more warm-up time beforehand. The ideal working temperature is around 30–40 °C at the material's surface.
Tools and surface finishing
To achieve very smooth surfaces without tool marks, use isopropyl alcohol 99.9 % applied with a flat brush or fingertips. The alcohol acts as a surface lubricant that seals micropores and smooths without dissolving the material. Avoid water: it is not compatible with mineral oil-based clays. The Tiranti BM series modelling tools are especially well suited for working Chavant Hard thanks to their polished stainless steel.
Compatibility with other materials
Although Chavant Hard is sulphur-free and does not inhibit platinum silicones, be careful if other materials are present in the same piece: cyanoacrylate adhesives, some freshly applied acrylic paints and uncured epoxy can create localised inhibition spots. If you are combining Chavant Hard with other materials to build the original, always carry out a cure test on a small offcut before pouring silicone over the full piece. For quickly adding structural volumes, the Masilla Epoxica 610 is a good rigid base to sculpt over with Chavant Hard, always making sure the epoxy is fully cured before contact with platinum silicone.
Frequently asked questions
What is the difference between high, medium and soft hardness in professional oil-based clays?
Hardness determines how much resistance the material offers to the tool. The Hard (high) variant like Chavant Hard requires more pre-warming but offers greater detail retention, cleaner surfaces and better behaviour in CNC milling or 3D scanning. Chavant Medium is more comfortable for long organic sculpting sessions. Chavant Soft is ideal for very fine details and cold work with little prior preparation.
Can I pour platinum silicone directly onto my original without doing any prior test?
If the original is made solely with Chavant Hard, yes: being sulphur-free it does not inhibit platinum silicones. However, if the piece combines several materials (adhesives, paints, other types of clay), always carry out a cure test on a small offcut before proceeding with the full piece. It is a step that saves both time and material.
How do you soften a high-hardness professional oil-based clay?
Warm it gradually with a heat gun, under an infrared lamp or in a low-temperature oven (maximum 85 °C). Avoid the microwave because heating is uneven and can burn localised areas. Once the surface is soft, knead the block to even out the temperature inside.
Is it possible to machine or CNC mill this clay?
Yes. Chavant Hard is specifically formulated to withstand CNC machining. Its high hardness prevents the cutting tool from deforming the material and allows clean edges and precise radii. Keep the piece at room temperature during milling to maximise rigidity.
Can leftover clay or offcuts be reused?
Yes, Chavant Hard is 100 % reusable. Collect the offcuts, warm them until soft and reincorporate them into the main block. It does not degrade through heating and cooling cycles within normal usage ranges.
What tools are most suitable for working with a high-hardness clay?
Polished stainless steel tools are the most recommended because they do not stick to the material and allow clean lines. The Tiranti BM series modelling tools are a standard reference among FX and prototyping professionals. For smoothing, a flat brush with isopropyl alcohol 99.9 % gives excellent results.
Can this clay be used to sculpt special effects prosthetics?
Yes. Chavant Hard is commonly used in FX to sculpt prosthetic originals that are then moulded with platinum silicone. Its compatibility with platinum silicones and the level of detail it allows make it an industry standard. For the mould, an FX-grade platinum silicone is recommended; check the Feroca catalogue to find the most suitable one for your application.
What is the difference between Chavant Hard and other vegetable-based industrial clays?
Vegetable-based industrial clays such as Feroca's Industrial Clay are formulated for general workshop use and may contain sulphur, making them incompatible with platinum silicones. Chavant Hard is specifically developed to be sulphur-free and to offer a superior surface finish, aimed at artistic modelling and high-precision prototyping.
