While perusing the weekly period articles at the USNLP website I ran across this clipping from the Lowell Daily Citizen and News (MA).
Cow-Cotton.”—A friend in Tennessee has sent us a specimen of “cow-cotton,” a novelty among manufacturers, uniting in its fabric both the animal and the vegetable kingdoms, being a mixture, half and half, of cotton and cow hair. It makes a cheaper and stronger fabric than all cotton for common clothing. Its gray color, its coarse grain, its tough fiber, give it a little of the old-time homespun look, when men wore linsey-woolsey. The mode of manufacture is by hand-carding, as practiced by our mothers and grandmothers. If the pure southern stuff that is fed to the Manchester mills should utterly fail, the English aristocracy may be glad to hear that their backs need not go bare, but can be clothed with cow-cotton.—Independent
Austin State Gazette, April 26, 1862, p. 4, c. 1
Cow Hair vs. Wool.—The manufacture of cow hair mixed with cotton has recently been introduced with perfect success. It is said to be quite as warm and durable for coarse fabrics as wool and cotton. It is being manufactured in considerable quantities in Tennessee. One whole company has been uniformed with it.—Ex.
There is another mention of cow-cotton in the Charleston Mercury in 1861.
Thought maybe you civilians would also find in interesting and could explain the hand-carding technique for this gunboat sailor.