A series of dry suit face, neck and wrist seals displaying extensive evidence of degradation in terms of soft, black material and cracking have been analyzed. The soft and sticky material located primarily around the trimmed edges in the degraded seals was identified as oxidized natural rubber. The chlorinated rubber surface showed signs of cracking and chlorine level decreased as a function of the degree of degradation. The later stages of oxidation of natural rubber include hardening and rubber cracking.
The oxidation of the rubber likely is caused by the presence of transition metal elements such as iron (up to 550 ppm) and copper (up to 100 ppm), which were identified in high concentrations in the degraded samples. Metal contamination is taking place primarily from the outside of the suit. The direct detection of iron oxide particles on the sample surface suggests that the contamination is likely coming from the soil being stirred up with the water during diving expeditions.