The following is an infallible and simple commercial test of the purity of white lead:
“Take a piece of firm, close-grained charcoal, and near one end of it scoop out a cavity about half an inch in diameter and a quarter of an inch in depth. Place in the cavity a sample of the lead to be tested, about the size of a small pea, and apply to it continuously the blue or hottest part of the flame of the blow-pipe; if the sample be strictly pure it will, in a very short time, say in two minutes, be reduced to metallic lead, leaving no residue; but if it be adulterated, even to the extent of ten per cent. only, with oxide of zinc, sulphate of baryta, whiting or any other carbonate of lime (which substances are the principal adulterations used) or if it be composed entirely of these materials, as is sometimes the case with cheap lead (so-called), it cannot be reduced, but will remain on the charcoal in an infusible mass.
“A blow-pipe can be obtained from any jeweler at small cost. An alcohol lamp, star candle, or a lard oil lamp furnishes the best flame for use of the blow-pipe. This test is very simple and any one can very soon learn to make it with ease and skill.”
JAPAN.
Always cut your japan in a little turps before you add it to the paint. An ounce of japan, cut with turps, will do better work than two ounces in oil paint, if put in clear. Don’t add dryer to any more paint than you can use up in a few hours, because it will soon commence to fatten your paint in the pot and lessen its covering and wearing properties. Many a job has been spoiled by using old color, doped with japan. Such paint is liable to mildew.
OBJECTIONS TO THE USE OF CHEAP DRY OCHRE AS A PRIMER.
1st. It is too dark for light colored work, because sooner or later it will show through in spots, or darken the entire work.
2d. It leaves a rough, coarse surface which the succeeding coats fail to completely level up.
3d. Succeeding coats are liable to scale from cheap coarse ochre priming.