of accidentally substituting one for the other, that to disregard this advice was simply to invoke dire disaster. No valid reason was ever given for this precaution ; but it was imperative, and any deviation was equivalent to some dreadful accident, explosion, spontaneous combustion, or something equally harrowing. Today all the colors of the mineral palette are mixed with as much freedom as are those of oil or water.
Still another erroneous impression that has been exploited with equal persist ency was that a steel palette knife was not to be used with certain colors,----that they would be ruined in consequence of contact ; and, above all, the importance of rigorously excluding a steel knife from gold was strictly enforced.
If precautionary measures be adopted to prevent the steel knife from rusting, and to keep it clean,---immaculately so,---there is no reason it should not e used for every purpose. It is the oxidation of the steel that does the damage to gold and the gold colors, as well as blue, if the rust is allowed to accumulate, and become incorporated with the pure metal or color.
The preventive is cleanliness. Decorators who work in factories run no risks ; for work means something serious to them, and they use invariably the regulation steel knife.
