So you’ve chosen to go with an oil based-clay for your sculpture but you’re not sure which consistency to choose. Soft, medium, firm, hard—besides the obvious, what’s the difference?
The answer largely depends on you.
What are you sculpting? A large, monumental piece? Something relatively small; say, tabletop size? Or are you sculpting miniatures with exceptionally fine detail?
Soft clays like Chavant’s NSP Soft or J-Mac’s 2-AB250 Classic Clay are ideal for larger sculptures, as they allow the artist to manipulate large areas of the sculpture with relative ease. With a larger surface area to work on, details in large figurative sculpture are generally easy to model, so a soft clay works just fine.
For something tabletop size, however, artists typically choose a medium clay, as medium clays offer the best of both worlds: they hold detail pretty well and also model pretty easily. For this reason, medium clays tend to be the most popular.
Hard clays, or clays that are sometimes referred to as firm, are best used for smaller sculpture requiring fine detail. Owing to their consistency, hard clays are easier to tool, which allows for more precise modeling of the clay.
Ultimately the consistency of the clay you choose should be a personal choice informed primarily by the level of detail you wish to achieve in your work. The harder the clay, the better it will hold detail. The softer the clay, the more easily it can be manipulated.