The Secret of the Old Masters - Softcover

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ... CHAPTER III THE THREE OILS While on the subject of oil it may be useful to note some of the constituents and character of the oils used generally by artists, as ascertained by the noted German chemist, Pettenkofer. Without entering into the chemical details, in a general way it may be stated that of the three oils--linseed, poppy, and nut oil--linseed contains a higher percentage of the "linolein" or real working and durable part of the oil. The proportion of ' linolein' in linseed is eighty per cent, in poppy seventyfive, in nut sixty-seven, according to Pettenkofer. The other twenty, twenty-five, and thirty-three per cent respectively of the oil constituent is a mucilaginous substance, and in proportion to its presence in quantity is deleterious and injurious. It produces opacity and hinders a quick drying. In my judgment the manner in which the oil is expressed from the seed is the important part. If the seed is pressed too hard, as seems to be the rule nowadays with hydraulic presses of great power, the ground linseed meal being constantly in direct contact with steam, it is not surprising that the undesirable substances are expressed with the oil. It seems to me that the old, slow Italian process is the best, where each artist made his own oil from the seed by a slow water process with the aid of the sun, without steam or pressure, and without the mixture of injurious chemicals. This is the safest kind of oil to employ. But if pressure must be resorted to, it should not be so excessive. The oil itself varies in the same seed, supposing all the time you have the best, full-grown, ripe seed. The first pressings are the best. The difference in color is the only thing to make some artists favor poppy oil in preference to linseed, the...