Scientific American 20, 16.11.1861
Considerable feeling was lately manifested by woolen manufacturers in Boston on account of some large orders which had been given by the Adjutant General U. S. A. for English army blankets. They protested against sending abroad for such goods, and it was asserted the mills in New England were capable of supplying all the demands of the War Department. This may be true with regard to the capacity of our blanket woolen mills, but unless our military regulations be changed we shall yet have to send to England for large supplies of army cloth. It is well known that dark blue is the chief color required for the coats of the officers and privates of the army and navy, and we do not overstate the number when we say there are not far from six hundred thousand men now wearing military uniforms. The amount of dark blue cloth for equipping this great host will be about four and a half million yards per annum, allowing three coats to each man. This is now putting the allowance too high for men engaged in hard warfare, especially when it is also taken into consideration that a large portion of the army must also be furnished with dark blue overcoats. Can our manufacturers supply this large quantity of cloth? We believe they cannot; and we think they have never manufactured the finer qualities of army cloth. In conversation a few days since with a customer clothier who frequently furnishes suits for many of the highest officers in the regular army, he informed us they always wanted the best cloth, such as maintained a fresh appearance from the day it was put on until it was worn threadbare. The West of England blue broadcloth was usually selected as possessing this quality. Beside the blue coats required for our army and navy, the officers wear dark blue trowsers, and so do the entire cavalry. The color of the trowsers, and so do the entire cavalry. The color of the trowsers and overcoats of the infantry soldiers, who are clothed in the United States' uniform, is also blue, but its tone is quite light. For the entire annual equipment of our army and navy in uniform, we may safely allow one-half the quantity of cloth for trowsers that is necessary for coats, thus making the total six and three-quarter million yards of indigo-blue cloth.
Our manufacturers, we are told, cannot obtain a sufficient supply of indigo to dye the amount of wool required for one-half this amount of cloth. Never before have we required so much of this coloring material, and never before was the supply so limited, the stock of the finer qualities being nearly exhausted. A dealer in indigo told us a few days since that he could sell fifty cases of it for every one he has on hand or can get. The East India crops of Bengal and Manilla indigo were greatly reduced last year by disturbances among the cultivators, and the crops in South America were unusually light. These facts and circumstances lead us to conclude that we shall yet have to send to England, which commands such a large share of the world's indigo crop, for very large stores of indigo unless our military regulations are greatly relaxed so far as they relate to permanent colors. We have no hesitation in asserting that durable dark blue colors can be dyed with logwood. They will withstand exposure until the uniforms are worn out, and this should be satisfactory. Such colors are dyed by several "boiling dips" alternately in a weak mordant of sulphate of iron and a bath of logwood until the proper tone is received, then finished with a very weak liquor of blue galls. The color thus obtained will be as permanent as that of common black felt hats, which is well known to withstand sunlight and rain for a long period.
A blue color can be dyed, with logwood, upon wool with a variety of what are called "mordants." By preparing the wool with a sulphate of copper solution, then fyeing it in a logwood liquor, a blue color is obtained which, when new, is not unlike that of indigo, but it is photogenic, and soon fades when exposed to the action of sunlight. A very beautiful dark blue can also be dyedon wool with the prussiate of potash, the muriate of tin and a minute quantity of the nitrate of iron; after which logwood is applied to render the tone deep and rich. However pleasing this color may appear when new, it fades when exposed to sunshine and moisture. A mordant composed of the bichromate of potash and crude tartar makes a very good blue with logwood, but the sulphate of iron and logwood blue is the most tenable color. A logwood blue is neither so beautiful nor so permanent as the color obtained from alkaline indigo, still it will answer every purpose for common army clothing, and effect a saving of at least a million of dollars to the country.