This air-drying clay was formerly known as Efaplast Light. Being water-based, it has quite a different feel from normal Fimo polymer clay, and very different properties, so don't be misled by the branding. The bit about it being light is very accurate, though - in fact it's really slightly disconcerting at first, just how light it is. It's like working with marshmallow or something. It is also, incidentally, always light-coloured - it comes in white, pale blue, pale red, pale yellow or a kind of ashy grey that I think they officially call 'black'. The paleness comes from the texture, and a coat of PVA or varnish should bring out richer tones.

Considering its near-weightlessness, it is impressively strong - perhaps slightly stronger than standard Fimo, and certainly much better at supporting its weight, since there is so much less to support. That makes it much easier to give a sculpture raised arms or wings than it is in Fimo, in which some poses really demand the use of an armature. Of course, despite its amazing strength-to-weight ratio, it is hardly substantial, and in particular any cracks or sub-standard joins can make a piece very fragile. It is worth looking out for cracks, and keeping some water on hand to smooth things over. It is also useful to use water to make a stronger join between two pieces, much as you would use slip with ceramic clay. This stuff is strong enough to use for things like masks, for which its lightness is a major asset, but you need to be pretty careful with it - it is flimsy enough that a lick of varnish will significantly improve its structural integrity.

I have often found air-drying modelling clay unsatisfying in the past - too many brands form skins while you are working, crack far too much, or just smell really weird. Only the cracking is ever a problem here, and I find it manageable. The clay stays workable for at least an hour, taking about a day to dry out completely. If you keep it carefully enclosed in something air-tight, it should keep for at least a few weeks - though it's best not to push it, since it will eventually go mouldy if you're not careful. Note that one side-effect of the lightness is that since it's sold by weight, it's easy to make the mistake of thinking it's much worse value than it really is.

Staedtler, who now own the Fimo brand, make a range of related clays - basic Fimo Air, Fimo Air Natural, Fimo Air Papier-Mâché and so on - but this is the only one that I have tried from that collection so far.

Here are some photos of sculptures I've made out of this clay.