I have not tried sculpy or Fimo clay. Does that burn out?
I do not know if they burn out, but I do know they can be toxic -
especially when heated above their normal baking temperature.
From "The Artist's Complete Health and Safety Guide"
third edition, by Monona Rossol, 2001, page 285, published in USA.
'Exposure to DEHP is worrisome, because it causes liver cancer and
birth defects in test animals. DEHP has been listed as a carcinogen
by the International Agency for Research in Cancer (IARC) since 1982,
Three U.S. agencies also consider it a carcinogen . . . Around 1990,
Polyform Products replaced the DEHP in Sculpey with a chemical called
di(2-ethylhexyl)terephthalate, or DEHTP. Eberhard Faber replaced the
DEHP in Fimo with a mixture of three phthalate plasticizers. All of
these chemicals are very similar to DEHP, but have never been studied
for cancer effects. Unfortunately, the Labeling of Hazardous Art
Materials Act allows products containing these untested chemicals to
be labeled "nontoxic." '
"Overheating by mistake in case of hardening in a oven can release
hydrochloric acid as vapor." This is claimed to be from an Eberhard
Faber safety data sheet. No date is given, so it is not clear if the
data is for the current formulation.
(apparently the owner of or distributor for Eberhard Faber) "FIMO is
Non Toxic and carries the CE mark. However, care should be taken when
baking as overheating (burning) can produce a gas." (Note that they
do not say which gas.)
Information problems found and fixed.