David Hamilton's review of 'Salt Glazing' (CR198) by Phil Rogers seems to conclude that there are no environmental issues caused by salt glazing. Unfortunately, research carried out and reported by those not involved in making saltglazed pots does not bear this out. 'Where did all the health and safety issues come from?' asks Hamilton. Well, they come from the inescapable chemical conclusion of the pottery salt glaze process: sodium chloride (common salt) reacts with water vapour to give hydrochloric acid plus sodium oxide, the sodium oxide then goes on to react with silica to form the glaze. Therefore you can't salt glaze without some water vapour present and the formation of hydrochloric acid (HCl) is essential to the process. Water vapour is always present when you burn a carbon based fuel in a kiln. Chlorine will not be detected as it is hydrochloric acid which is given off. These 'noxious vapours' are evolved as white, heavy fumes from kiln chimneys.
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