What Causes the Odour of Natural Rubber?

Manufacturer: We are rubber products manufacturers using both synthetic dry rubber and latex. Recently, in response to customers' request, we started using natural dry rubber, especially the brown crepe. Compared with synthetic rubbers, natural rubber has a comparatively more objectionable odour. What causes this odour and what can we do to minimise it?

John Woon (Senior Latex Consultant): Actually, the rubber constituent i.e. polyisoprene of natural rubber itself is odourless. The smell comes from the "non-rubber" constituents, especially the protein. The degree of such odour depends on the production processes involved from the tapping of the tree to the final conversion into the dry rubber in the form of bales. The lower quality rubber made from cup lumps, field coagulum and scrap rubber resulted from the original latex coagulating naturally instead of the deliberate coagulation done in the factory, generally give stronger smell. The higher the extent of washing in the factory, the lower is the extent of odour due to the removal of the non-rubbers by the water.

Skim block usually has more objectionable odour because it contains greater amount of non-rubbers. You should insist on good quality Standard Malaysia Rubber with low volatile matter.

Having said that, the smell is lesser for the finale finished vulcanised products. If your customers still find your products unacceptable due to the residual odour, you can mask it with deodorants.