Experiments with Paints.

Scientific American 24, 20.2.1858

Artikkeliin lisätty rivivaihtoja lukemisen helpottamiseksi.We have received from John Ewen, Jr., of Williamsburg, L. I., an interesting account and proofs of experiments conducted by him to test the comparative durability of certain pigments, and the vehicles employed with them as applied in house painting. During the last twenty-three years, he has been practically engaged in house and sign painting, and in that period many questions had been asked of him regarding the best paints to use. "To these," he says, "I gave the best answers that a general and superficial observation would warrant; but not being reliably answered, they increased fourfold as the zinc paint came to be generally used. It was at this time (September, 1831) that a method of demonstration suggested itself. I forthwith procured two strips of board, and marked them into compartments, and after numbering them 1, 2, up to 11, I coated them in the following manner:
—No. 1 received too coats of white lead mixed with raw linseed oil, and no dryer; the paint was laid off or finished with the brush, stroked up and down.
No. 2 received the same coating of material as No. 1, but was finished with the brush passed right and left, crosswise.
No. 3 was given two coats of white lead, raw linseed oil, and considerable spirits of turpentine in the first, but only a little in the last coat.
No. 4 received two coats of white zinc and raw linseed oil—all mixed with what is called "patent dryer."
No. 5 the same as No. 4, but with no patent dryer.
No. 6 received a first coat of white lead and Paris white, equal parts, and clear white lead for the last coat, with raw linseed oil as the vehicle.
No. 7 was given two coats of white lead, with boiled linseed oil.
No. 8 three very thin coats of white lead, with raw linseed oil.
No. 9 got a very heavy prime coat of white lead, and a very thin second and last coat, with raw linseed oil.
No. 10 the reverse of No. 9, namely, a thin prime coat and a heavy finishing one.
No. 11 received two coats of Paris white and white lead, equal parts, with raw linseed oil.
After this was accomplished, mid the paints well dried, the two pieces of board were placed in a position where they were exposed to the weather—its sunshine and its storms—for years."

The following are the results obtained:
— "The white lead paints exhibited a decided superiority for durability over the zinc, and the squares finished with the brush up and down in vertical lines are decidedly superior to the one laid with the brush right and left. [This is undoubtedly due to the moisture being allowed to flow down more freely than in the square finished with the brush run transversely, which left small cross ridges of the paint.] No. 9, which received a very heavy prime coat, is white and chalky; No. 10 is darker in color, but not so chalky; No. 11 is superior to the two preceding numbers. Of all the squares, however, No. 7, consisting of two coats of white lead, with boiled linseed oil, is by far the best—the smoothest and closest."

Mr. Ewen has left the boards with us, and the apparent results are such as have been stated. The experiments are valuable, because they afford positive data regarding paints, and the manner of applying them to the outside of buildings, so as to obtain the best effects. The coating of white lead, with raw linseed oil and a little spirits of turpentine, looks well, and strikes us favorably. Raw linseed oil, in white lead, without turpentine, imparts a greasy appearance to white paint when first put on; a little turpentine, therefore, improves its appearance, but care must be exercised not to add too much, because when in excess, it imparts a saponaceous character to the paint, which makes it become chalky, and scales off rapidly by exposure to rains and winds.