Manufacturer: We are a small manufacturer of insulation gloves. We are encountering a lot of coagulum problems even after filtering the latex. Our latex specification has been sent to you. Please help us.

John Woon (Senior Latex Consultant): The MST should be a range, not a minimum number, such as 650 seconds. If it is set at a "minimum", the latex concentrate producers are free to deliver to you batches of latex with too high an MST, which is also no good (e.g., 2000 seconds)

Your latex concentrate is almost four months old. The MST today will be very much lower than the 650 seconds tested by the producer, because the stability of latex drops with storage time. 

The lower the MST, the lower the stability of the latex against shearing, such as during stirring and compounding. The end result could be what you are experiencing now, i.e., high coagulum level (evident in the photographs of your gloves)

I suggest you set a range of between 900 and 1500 seconds as your new MST specification.

For the interim, please add 0.05 phr (parts per hundred of dry rubber) of ammonium laurate soap to the latex, followed by stirring for two hours at low rpm.

Then filter the latex through 100 mesh sieves before use. If you still encounter the formation of coagulum, you can add another 0.05 phr of the soap.