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beware using salt for effects,

updated mon 31 mar 97


Gil Stengel on wed 12 mar 97

Ralph Loewenthal wrote:

>Please be very careful with salt, at higher temps it starts giving off
>= Chlorine gas - very poisonous. Not the sort of gas to have floating
>around school grounds. Please Clayarters when giving advice such as
>that above include the health hazard warnings. Do not assume anything.
>I thought I knew about the health risks, but I realise now that if I
>know 10=25 I am lucky. Just trying to err=
>the side of safety Ralph


I'm not aware of any data or chemical reasons to suggest that salt
under temperature gives off chlorine gas. Hydrochloric acid gas is a
more likely possibility. There is some recent research out of
England, published in the latest issue of Ceramic Review magazine,
indicating that no trace of Chlorine could be found in the gas
from a couple of salt firings. H20, NaCl and HCl are the much more
probable components.

Combining salt and colorants and applying them to ware is a worthwile
area of exploration. The small quantities of NaCl involved should
pose no health risk, to school yards or anyone. If anything,
airborne release of metal oxides from such a technique would be a
minor concern but probably not any more of a concern than in the
firing of many glazes.

Everyone certainly should err on the side of safety. In addition,
assumptions should not be made.

Gil Stengel