Please help identify this mystery Cobb card, what the heck is it?

[Leon]

It really shouldn't flouresce at all if it is period to Cobbs playing days. This is taken from a David Rudd Cycleback (hi David) site...

"Starting in the late 1940s, manufacturers of many products began adding optical brighteners and other new chemicals to their products. Optical brighteners are invisible dyes that fluoresce brightly under ultraviolet light. They were used to make products appear brighter in normal daylight, which contains some ultraviolet light. Optical brighteners were added to laundry detergent and clothes to help drown out stains and to give the often advertised `whiter than white whites.’ Optical brighteners were added to plastic toys to makes them brighter and more colorful. Paper manufacturers joined the act as well, adding optical brighteners to many, though not all of their white papers stocks."


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