Modelling clay

Clay has been used for modelling from the beginning of civilization. Colors vary from bright red, yellow, terracotta and a creamy color to black. Classically, terracotta was the preferred material; it is still very popular. Modellers also prefer grey which dries light grey and then can readily be painted. In technical terms it is made up of very finely grained hydrous silicate particles, which is more precisely described in clay.

Nylon-reinforced clay

A relatively new product variation of earthen clay is clay reinforced with filaments of Nylon. It is used by modellers who do not intend to fire their works. This is designed to bond the clay more tightly and therefore reduce the incidence of cracking.

Modelling large models with earthen clays is made difficult because clay shrinks unevenly when it dries. It is therefore essential that the model is dried very slowly otherwise fatal cracking occurs.

Cracking can also be minimised by using an internal supporting frame (armature) of wood, wire mesh, polystyrene or similar materials made to the rough shape of the intended object and then finishing the model with a layer of clay no more than 15 mm thick.

Firing earthen modelling clay

Modeling clays both natural and Nylon reinforced can be fired at a kiln temperature in the range of 1000 °C to 1250 °C. When firing a model, modellers should take care to ensure that their armature (frame) can withstand these temperatures without breaking down or releasing explosive or noxious fumes. Models can then be glazed in the same way as pottery clay. The Nylon does not affect the glazing process.


Plasticine was invented in 1897 by William Harbutt of Bathampton, near Bath, Somerset, England, an art teacher who wanted a non-drying clay for use by his sculpture students. Since then, Plasticine has since become a generic term, especially in the Commonwealth, for modelling clay.

As well as being very slow drying, Plasticine has other properties of advantage to artists. Being oil-based, it is not soluble in water. When warmed to body temperature of around 35°C, it is easily worked but when cooled to room temperature of around 20°C, it stiffens and becomes very stable. It can be re-used and so is an ideal material for animation artists who need to rework their models. It is available in a multitude of colours, is non-toxic and is therefore suitable for use by children.

Being readily worked in fine detail, Plasticine is also suitable for the creation of an original work from which a mould (molding) can be made. Castings and reproductions in a much more durable material can then be produced.

There is now a variety of similar products on the market, including (in the UK) Newplast and Colour Clay.

Polymer clay

Polymer clay is a type of clay that will harden permanently when baked at a low temperature. Polymer clay hardens by curing at temperatures created in a typical home oven generally at 265 to 275 °F (129 to 135 °C) for 15 minutes per 1/4" (6 mm) of thickness and does not shrink or change texture during the process. When properly cured, most items won't break if dropped or normally stressed. Polymer clay also comes in liquid form and in permanently flexible solid form. Polymer clay is sold in craft, hobby, and art stores, and is used by artists, hobbyists and children. Leading brands of polymer clay include Premo, FimoClassic and FimoSoft, Kato Polyclay, Sculpey Cernit, Formello and Modello and Das.

Wax-based clay

A modelling clay based on a mix in various proportions of wax, oil and filler materials (such as sulfur). Commonly used in clay modeling while developing car designs. Also known as clay (industrial plasticine).

Paper clay

There are two major groups of paper clay/paperclay users.

There are those using paperclay as an unfired body and those using paperclay in the studio ceramic studio to make sculptural and functional ceramics.

  • Studio ceramics and paperclay
  • Airdrying modeling clay

Commercial air drying clay does not shrink noticeably when drying. This paper clay can be painted, varnished, drilled, sawn, cut and glued. There is brand of paper clay called Fun Fair Paper Clay which is aimed at children. Model Magic by Crayola is a similar product.

See also

  • Papier-mâché (paper-maché), construction material made of paper and a wet paste


Sources consulted Endnotes

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