Natural Rubber Latex Thread - Resistance to Dyeing

Manufacturer: We are manufacturer of natural rubber thread using latex extrusion process. We have received complaints from our customers that their garments lost the elasticity property after the dying process. What could have caused this problems and how can we eliminate or minimize this problem?

John Woon (Senior Latex Consultant): I believe this could be due to the following reasons:

1) The nature and type of the dye itself. Some inorganic dyes contain transition metals such as copper, manganese and iron which act as "pro-oxidants" that catalyses the oxidation of the rubber. If this is what your customers are using, I suggest they switch to organic type of dyes.

2) The condition of the dyeing process which entails pH, temperature and time. Often the dyeing process is done at alkaline pH of 9 - 12 which would tend to extract the accelerators and antioxidant from the thread leading to poor resistance to oxidation.

Of course, the higher the temperature and the longer the time, the worst would be the situation. I therefore recommend that the dyeing process be carried out at a pH approaching neutral, at lowest possible temperature and shortest possible time.

Also, make sure that water used for washing does not contain trace amount of copper.