Sio-2 PLUS Terracotta Clay

Sio-2 PLUS Terracotta Clay is a high-plasticity natural clay that air-dries without the need for a kiln or firing, reaching a hardness comparable to fired ceramics. Its natural terracotta colour, the presence of cellulose fibres that prevent cracking during drying, and its easy water-based cleanup make it a reliable choice for professional workshops and schools as well as creative use at home from age 3.

Technical specifications

What it's used for

It is a versatile clay covering a wide range of uses, from art education to decorative piece production and manual prototyping. Its terracotta colour provides a visually warm finish even before painting, making it especially interesting for decorative and sculptural pieces.

• Hand modelling of figures, sculptures and scale models
• Throwing on a potter's wheel
• Creating fine details and reliefs on decorative pieces
• Plastic arts workshops in schools and art centres
• Making pieces to be painted, varnished or decorated afterwards
• Prototyping and modelling shapes for later reproduction in silicone moulds
• Supervised creative activities for children (from age 3)
• Volume production for workshops thanks to the large 5 and 10 kg formats

How to use it

1. Open the packaging and take out the amount of clay you need. Close the rest tightly to preserve moisture.
2. If the clay is slightly dry on the surface, briefly knead it with slightly damp hands until it regains uniform plasticity.
3. Model with your hands or with modelling tools and loop tools to achieve fine details or hollow forms.
4. To join pieces or add volume, use a little water or very wet clay (slip) as an adhesive at the joints.
5. Leave the piece to air-dry at room temperature on a non-porous surface or rack, turning it periodically for even drying. Large pieces may take several days.
6. Once completely dry and hard, you can sand the surface with fine-grit sandpaper, drill it or carve it as needed.
7. Apply acrylic paint, tempera, oil paint or any varnish over the dry piece to colour or protect the finish.

Usage tips

Storing and reviving the clay

The key to keeping Sio-2 PLUS Terracotta in perfect condition is to prevent it from drying out before use. Always store the unused block in its original tightly closed packaging, or wrap it in cling film. If the clay has lost some moisture and become brittle, you can revive it by wrapping it in a damp cloth for several hours, or by placing small fragments in a sealed bag with a few drops of water and leaving it to rest until it rehydrates.

Crack-free drying for large pieces

The cellulose fibres in the Sio-2 PLUS formula minimise the appearance of cracks, but with large or thick-walled pieces it is advisable to take additional precautions. Model with uniform wall thickness — ideally hollow on the inside — to facilitate moisture evaporation. Cover the piece with a slightly damp cloth during the first 24 hours to slow initial drying and reduce internal stress. Drying too quickly in very warm or draughty environments can generate cracks even with this clay.

Finishes and painting

The terracotta colour of the clay already provides a very pleasing final look without any need for painting. If you want to colour the piece, wait until it is completely dry and hard throughout — not just on the surface — before applying any paint or varnish. Acrylic paints are the most common choice for their ease of use and quick drying. If you plan to apply several coats or want a very smooth finish, a light sanding with fine-grit paper beforehand noticeably improves adhesion. For outdoor decorative pieces, apply a waterproofing varnish: air-dried clay is not inherently waterproof.

Frequently asked questions