Storing Fimo

I emailed STAEDTLER who manufactuer Fimo about storing it. Here is their response

Please store unpacked material wrapped in aluminium foil, in tins or plastic bags (PE / PP). Please avoid unhardened FIMO coming into contact with polystyrene (PS), PVC or Styrofoam, since the surface may undergo a chemical change - as described in your mail.

So now you know ;)