Chemical Blooming and Copper Staining

Manufacturer:We have been having chemical blooming and copper staining problems on our dipped latex films. We believe this is due to ZDEC (Zinc Diethyldithiocarbamate) we are using.
How could we minimize these problems? For some reasons we cannot reveal, we have only a choice among ZDMC, ZDEC and ZDBC.

JohnWoon:Among the 3 common dithiocarbamates you mentioned, ZDBC has the least tendency to bloom due to it being the most soluble in rubber. For the same reason, ZDBC would be expected to have relatively lower tendency to cause staining in the presence of trace copper. The usual yellowish to brownish stain is due to the formation of a complex of copper dithiocarbamates.

Please take note that the activity and solubility of these dithiocarbamates in rubber increase as the chain length of the alkyl group increases.

Having said this, you have to be careful in your reformulation as ZDBC has a faster curing rate at room temperature compared to ZDEC. Please refer to my more detailed report despatched to you separately.

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