Method of finishing a slide fastener chain

In the manufacture of a slide fastener chain having a pair of stringer tapes coupled together and a row of filamentary coupling elements having a succession of loops and secured by a binding thread system to a longitudinal edge of each of said tapes, said binding thread system partly covering at least one of upper and lower surfaces of said loops of the coupling element row, the method which comprises the steps of:

• (a) transporting said fastener chain unidirectionally at a constant rate of speed;
• (b) passing said chain through a first treatment zone where said chain is thermally preset at a temperature to permit the fibers of said stringer tapes and said binding thread system to become thermally contracted;
• (c) subsequently introducing said chain into a second treatment zone where said binding thread system of said chain is thermally compressed at a temperature similar to that in said first treatment zone, whereby said binding thread is plastically deformed to assume a transverse cross section substantially identical with that of a slider guide channel;
• and
• (d) cooling said chain to set it, said rows of coupling elements being coupled together prior to, and remaining coupled together during, the passing of said chain through said first and second treatment zones.