Digital BW, The Print

I am carrying out a home-brew test of Nanochrome ink. I have taped two 
prints on a window in full sun, both printed on my Epson 2200, both on 
Pictorico Gallery Glossy paper, one using OEM ink and the other using 
Nanochrome ink. I know this isn't very scientific, but it should 
answer the question, "Is Nanochrome dye/resin ink more, less or equal 
in light fading to Epson OEM pigment ink?"

The prints have been in the window for a week and neither are showing 
any discernable fading along the edge of black cover cards. Has anyone 
tried this sort of test? How long can I expect to leave the prints in 
the window before I see some fading in one or both prints?

Les