A quick way to find out if the recording tape is BASF or AMPEX?

This is just a preliminary observation.


It may prove helpful if all other clues are missing.


The black back coating reflets light in a very different way.


The BASF seems to reflect as if the black back coating is more polished. The AMPEX back coating does not.


...Tapes with mixed misplaced boxes are being tried to be paired correctly. 1/4in tapes of 600ft compared were BASF SM911 and  possibly AMPEX 406.


If stronger light, not needed really,  is used make sure you use eye protection.