Is it possible that in the UK there is a different material sold as
Jet Dry? I went to several MSDS databases and all of them list Jet
Dry as non hazardous
James, I found that the manufacturer's MSDS sheets were indeed
generally as you stated, but a wider search found that the active
ingredients were 60% citric acid and 40% sulphamic acid (sulfamic in
the States) approximately.
Sulphamic acid is an interesting compound (Wilkipedia does a good
article on it) but for metal-smithing purposes can be regarded as a
strong acid - stronger than citric or phosphoric acid, but not as
strong as the three main mineral acids (hydrochloric, nitric,
sulphuric). The toxicity appears to put it somewhere in the same
class as these latter three acids.
I use it as a tarnish remover for metals, 5% in water with 5%
thiourea added. This is a similar formulation to various 'Silver