To my knowing, elementary / metallic silver isn't photosensitive in any way? And again, to my knowing, the permanence issue with any of the processes which results with a nanoparticle silver image is related to the vulnerability of silver nanoparticles to (1.) chemical impurities left in the support (due the nature of the process and/or bad processing - e.g. iron ions left in paper, ... etc.) and/or (2.) atmospheric pollutants (e.g. sulfur dioxide, peroxides, ozone, ... ect.) and/or (3.) other factors, but not to the effect of light, because, elementary / metallic silver image simply doesn't fade in light! Does it?
P.S. Nice first print Matt!!! Vandyke is beautiful and (if toned) very very permanent.
Well said Loris and I have many prints dating back many years that are still the same (thanks to the use of Borax).