The Oxide of Zinc as Paint.

Scientific American 8, 10.11.1849

A correspondent of the United States Gazette, in commenting upon the value of zincwhite as a substitute for white lead, and combatting some objections that have been urged against its use, says that the principal obstacle to its employment has been the difficulty of working the material which arises from the fact, that workmen who are acustomed to a certain routines of practice, are at fault when a new article is set before them, and after attempting to use it according to the method with which they are acquainted, and not finding it to succeed, condemn it as useless. Although persuaded of the beneficial results which would follow from the use of zinc white, the masters will not take the trouble to look into the matter themselves, but rely upon their workmen, and thus the public is persuaded that the application is impracticable.

The first thing is to procure oil as nearly white as possible; this is essential, if a bright color be required, for as the zinc white possesses less body than white lead, colored oil imparts a color to it which tarnishes its brightness; if, however, a yellow color be required, there is no occasion to be so particular about the whiteness of the oil. The most suitable oil - which is generally white enough - is the oil of the black poppy, which may be procured from Flanders and Alsace, where it is in common use. In default of this, any other siccative oil may be used, provided it be white.

The zinc white may be ground, while dry, into a powder, with the mullet; it must then be scraped with a painter's knife into a heap in the middle of which a hollow is to be made to receive a small quantity of oil; the whole is then to be mixed with a knife, so as to bring it to the consistence of thick mortar, or paste, and rather dry than otherwise. This paste is then spread upon a separate pallet, from which a small quantity is taken and put under the mullet and ground. It is scraped up tith the knife, and placed in heaps on the stone, where it is again ground, the bullet being carefully placed upon the centre of the heaps. When, by this means, the color is spread over the whole surface of the stone, three or four times, from one end of the stone to the other, the whole must then be scraped off with a knife. This operation soon becomes easy of perdormance, as zinc white has a fine and easily separated grain. If it be too liquid, it will be necessary to add a sufficient quantity of powder to give it the required consistency, and again grind it. It is then to be put into a clean vessel, containing clean water.

When large surfaces are to be painted, the brushes used must be very soft and not too close in order that the color may be laid equally.

As a substitute for white lead, zinc was first used in France, and the above is a too highly colored picture of its merits taken from a French journal. It will never come into use in this country, for common white, if we have to go to Flanders for poppy oil, nor can it (the zinc) be profitably applied, except mixed with the only oil that should be used, viz., good linseed.

The following is Mons. Rochaz's method of using the white of zinc, as recently patented in England, viz.:

The patentee makes a durable white paint or pigment by taking twenty parts of the oxide of zinc, four parts of resin, two parts turpentine, and one part drying oil.

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