Nickel in powdered mineral form is a known carcinogen, causing lung and nasal tumours on inhalation, however, different forms of it have different toxicity levels. Nickel Oxide, the type most frequently used by potters, is luckily one of the least toxic of the Nickels, although still should be handled with due care and respect. It is believed that nickel inhalation can increase the likelihood of lung cancer by 3 to 7 times, so be sure to wear adequate protection if you’re using it.
Aside from the significant carcinogenic danger, inhalation of Nickel Oxide can result in lung irritation and asthma, pulmonary edema, pneumoconiosis and pulmonary fibrosis. These are alongside the more immediate symptoms, many linked to ‘metal fume fever’, which presents like the flu.
As with most metallic compounds, direct contact can cause sensitivity including a burning or itching sensation and possible dermal rash with pustules.
At high temperatures Nickel Oxide becomes volatile and can generate fumes, this may result in the glaze blistering or pin-holing. It serves to tone down the vibrancy of other glaze colourants.
Barium = Pink Cobalt – Grey/Blue Titanium = Crystallisation of glaze (a ratio of 1:10 Nickel to Titanium) Zinc = Range from Yellow to Blue, depending on proportion of Zinc to Nickel and percentage of both within the glaze (as more Zinc is added it will move through Brown to Reddish Purple and Dark Blue)