2. Various Processes
Use of Cellulose
All the processes that have met with any success are based on the use of cellulose in some form, as a foundation. The two sources that have proved most successful are wood-pulp and cotton and it may be said that the bulk of the artificial silk on the market comes from one or the other of these two raw materials.
Chardonnet Process
The Chardonnet process uses cotton as its base. It is first bleached, then by chemical treatment is changed to nitro-cellulose, which is dissolved in alcohol and ether and thus made ready for “spinning.”
Viscose Process
The Viscose process, which has made great strides in recent years, makes use of a pure grade of sulphite wood-pulp. This pulp is in sheet form and is first treated with a solution of caustic soda, then shredded very fine and put through several more chemical treatments, finally being dissolved in water preparatory to the “spinning.”
“Spinning”
In both of the above methods the production of the thread is the same. The solution, whether it be based on cotton or wood-pulp, is forced through minute holes and comes out in a thread-like stream, which solidifies when subjected to a setting bath. It is then washed, dried, and put through processes, such as twisting, reeling, etc., very similar to those which natural silks undergo.