DYEING AND DYESTUFFS 



1892 



DYNAMICS 



DYE 'ING AND DYE 'STUFFS. Dyeing is 

 the art of permanently coloring textile fabrics 

 and other materials. The term dyestuffs is 

 applied to all chemicals and other products 

 used to obtain the desired colors. Dyeing is 

 one of the most ancient of arts. It was prac- 

 ticed in prehistoric times and reached a state 

 of perfection centuries before the Christian 

 Era. The ancient Egyptians employed mate- 

 rials ;md processes for dyeing similar to those 

 now in operation. As early as 1000 B. c. the 

 city of Tyre was noted for its purple dye, 

 which has not been improved upon by the 

 most modern scientific processes. Cloth dyed 

 with the purple of Tyre was so valuable that 

 the Emperor Diocletian issued an edict in A. D. 

 301 fixing the price of wool so dyed at $350 

 per pound. The Greeks and Romans were far 

 behind the ancient Egyptians in knowledge of 

 dyeing, but during the early wars with the bar- 

 barians of the north they appear to have alto- 

 gether lost the art. Julius Caesar found the 

 Britons well skilled in dyeing, using chiefly 

 products of bark and wood. 



Dyestuffs. Modern discoveries have to a 

 great extent superseded natural dyestuffs, with 

 the exception of indigo, and most of the com- 

 mercial dyes are products of coal tar. Animal 

 fabrics, such as wool and silk, are more readily 

 dyed than vegetable products like cotton and 

 flax. The coloring matter quickly adheres to 

 wool and silk, after being prepared by cleaning 

 for the application of the dye. Cotton will 

 not take dye direct, and the coloring matter 

 must be supplemented by some other sub- 

 stance, the action of which tends to make the 

 cotton and the coloring matter combine. There 

 are many substances, called mordants, which 

 are used for this purpose. Those most com- 

 monly employed are alum, aluminum salts, 

 salts of iron, tannin, albumen and gluten. 

 Stuffs needing mordants are first plunged into 

 a solution of mordant salts and then treated 

 with ammonia, lime, sodium phosphate or 

 sodium arsenate to render the salts insoluble. 

 Then the stuffs are brought into contact with 

 the dye, the resulting color being formed by 

 the combination of the insoluble salts of the 

 mordant with the coloring matter of the dye. 



The apparatus used in dyeing is simple in 

 construction, consisting of vats, kettles and 

 cisterns of iron, wood or stone. The water 

 used in washing the fabrics must be pure; any 

 contamination tends to destroy the color effect. 

 Wool, cotton and silk may be dyed before 

 being woven, or may be dyed in the piece 



after weaving. Mixtures of cotton and wool 

 usually require two dyeing processes. The 

 cotton is first treated, and the finished weave 

 is brought to the required color by a dye that 

 affects only the wool. 



German Supremacy. The War of the Na- 

 tions, which began in 1914, had a serious effect 

 on the manufacture of fabrics in the United 

 States and Canada, owing to the fact that the 

 importation of dyestuffs from Germany, where 

 their manufacture had reached the highest per- 

 fection, entirely ceased. Both North and South 

 America had for years relied on Germany and 

 Austria for many of the materials used in 

 dyeing. The German chemists have long been 

 recognized as supreme in this field, and Ameri- 

 can manufacturers had so far acknowledged 

 this supremacy that home production had been 

 almost entirely neglected. Thus out of dye- 

 stuffs valued at $7,118,528 produced in the 

 United States in 1914, over $4,653,000 worth 

 were coal-tar dyes, nearly one-half of which 

 were merely mixtures made in the United 

 States of artificial colors manufactured abroad. 

 These figures include only the stuffs intended 

 for sale; a number of establishments using 

 dyes produced their own stuffs and were per- 

 haps even more dependent upon foreign aid. 



When the supply from Europe was cut off 

 manufacturers were confronted by serious diffi- 

 culties. Certain colors could not be produced 

 without German dyestuffs. In one case it was 

 necessary for one of Iowa's colleges to change 

 its college colors, as they could not be pro- 

 duced in America. American chemists quickly 

 discovered the secrets of many of the German 

 processes, and produced dyes of good quality, 

 showing conclusively that if the matter had 

 been given earlier attention such utter depend- 

 ence on the European supply would have been 

 unnecessary. S.L.A. 



Related Subjects. The following articles in 

 these volumes contain informaton which will be 

 of interest in connection with the general article 

 on dyeing : 



Alizarin Indigo 



Aniline Mordants 



Carmine Sloe 



Coal Tar Turmeric 



Cochineal Woad 



DYNAMICS , di nam ' iks, from a Greek wor 

 meaning power, is that branch of physics whic 

 treats of the laws of force, or laws of motion 

 By force we mean that agency by which th 

 rate of motion of a body is increased or de 

 creased or its direction changed. All fore 

 are subject to the same laws. Force is me 





