One producer of rubber goods in the US is WH Salisbury Co. A catalog section on gloves is
www.whsalisbury.com/gloves/images/gloves.pdf [~3MB PDF] The section contains some information on ratings, inspection, use and storage.
Probably the most important aspect of glove use is that they should always be worn under leather protectors that are intended for the application.
In the US, rubber goods like gloves and insulating mats require periodic retesting to assure that their electrical and mechanical properties are not reduced.
Other information about ASTM D120 insulating gloves is in the linked catalog section. The “class” label color coding is
www.whsalisbury.com/gloves/images/astm_chart.pdf Salisbury’s home page is
www.whsalisbury.com
