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Water-repellent fabrics
584
NATIONAL BUREAU OF STANDARDSNOTES.
[J. I;. I.
required for successful tanning. Without them the iron precipitates as the hydroxide, a form useless for this purpose. Considerably more iron (Fet03) than chrome (Cr203) is required to tan a piece of leather. All hides tanned with the iron contained at least IO per cent. of Fe203, whereas good leather can be prepared from chromium salts which contain only 5 per cent. of CrZ03. Experiments with hide powder showed that as much as 25 per cent. of Fez03 combined under optimum conditions. Iron tanning solutions appear to have properties similar to those of chrome tanning solutions. Results of accelerated aging tests on iron tanned goat and calf skins indicated that, on the average, the iron . tanned leather is slightly less resistant to aging than the chrome tanned leather. WATER-REPELLENTFABRICS. The development of fabrics that shed water readily and yet permit the wearer to “breathe” through them is’especially important to the armed forces. Such fabrics can give protection against all but very heavy rains, and since they only absorb water very slowly, they remain As a means of relatively light in weight even under adverse conditions. testing such water-repellent fabrics, an improved apparatus, referred to as a “drop-penetration apparatus,” to simulate the action of rainfall, has been devised. Drops of controlled size fall at a constant rate upon the fabric to be tested. The length of time required for water to penetrate through the fabric is taken as a measure of its water-repellency, this time being indicated by means of an electrical signalling device. Water-repellent fabrics have been exposed to severe natural rainfall, as well as the action of the drop-penetration apparatus and good correlation has been found between the results obtained under the two conditions. TESTS OF SYNTHETICRUBBER. The Bureau is cooperating with the Rubber Reserve Company in its efforts for the production of synthetic rubber of uniform, high quality. Careful control so as to secure uniformity is necessary, because the I I synthetic rubber plants now in production are in widely separated localities from Connecticut to California and are necessarily operated Furthermore there are by newly-trained and inexperienced personnel. differences both in the processes and in the raw materials used. It is the desire of the Rubber Reserve Company, that the rubber from all plants shall be of such uniformity that it can be used interchangeably in the manufacture of rubber goods. To this end the Bureau is assisting in the development of well-defined specifications and in the improvement
NATIONAL BUREAU OF STANDARDSNOTES.
[J. I;. I.
required for successful tanning. Without them the iron precipitates as the hydroxide, a form useless for this purpose. Considerably more iron (Fet03) than chrome (Cr203) is required to tan a piece of leather. All hides tanned with the iron contained at least IO per cent. of Fe203, whereas good leather can be prepared from chromium salts which contain only 5 per cent. of CrZ03. Experiments with hide powder showed that as much as 25 per cent. of Fez03 combined under optimum conditions. Iron tanning solutions appear to have properties similar to those of chrome tanning solutions. Results of accelerated aging tests on iron tanned goat and calf skins indicated that, on the average, the iron . tanned leather is slightly less resistant to aging than the chrome tanned leather. WATER-REPELLENTFABRICS. The development of fabrics that shed water readily and yet permit the wearer to “breathe” through them is’especially important to the armed forces. Such fabrics can give protection against all but very heavy rains, and since they only absorb water very slowly, they remain As a means of relatively light in weight even under adverse conditions. testing such water-repellent fabrics, an improved apparatus, referred to as a “drop-penetration apparatus,” to simulate the action of rainfall, has been devised. Drops of controlled size fall at a constant rate upon the fabric to be tested. The length of time required for water to penetrate through the fabric is taken as a measure of its water-repellency, this time being indicated by means of an electrical signalling device. Water-repellent fabrics have been exposed to severe natural rainfall, as well as the action of the drop-penetration apparatus and good correlation has been found between the results obtained under the two conditions. TESTS OF SYNTHETICRUBBER. The Bureau is cooperating with the Rubber Reserve Company in its efforts for the production of synthetic rubber of uniform, high quality. Careful control so as to secure uniformity is necessary, because the I I synthetic rubber plants now in production are in widely separated localities from Connecticut to California and are necessarily operated Furthermore there are by newly-trained and inexperienced personnel. differences both in the processes and in the raw materials used. It is the desire of the Rubber Reserve Company, that the rubber from all plants shall be of such uniformity that it can be used interchangeably in the manufacture of rubber goods. To this end the Bureau is assisting in the development of well-defined specifications and in the improvement