Digital BW, The Print

I am impressed with the breadth of interest here in light values, 
cumulative lux and effects on fading.
Back in the old silver days there was that little bit at the bottom of a 
Density/Exposure curve where the toe didn't quite meet up with the 
Density axis. Silver halides had to get a kick of photons before 
additional exposure became evenly translated into density of solid silver.

Here's the thing. Do pigments and dyes act in the same way on exposure 
to light? Does anyone know if there is a linear relationship between 
accumulated lux and fading, or is there a toe on the curve whereby light 
energy has to achieve a threshold level before fading begins?. Just 
curious....

Whilst we want to nail down all the variables in our longevity quests, 
because we live in different climates, different airborne pollutants 
etc., there is now way that any lab controlled test can have meaning 
apart from providing poor relative guidelines. How can Wilhelm data 
generated in Europe have any meaning to me in New Zealand?. I sit in a 
humid, ozone depleted atmosphere with little pollution. 100 miles away, 
photographers live in a sulpher dioxide laden atmosphere in our 
geothermal zones. Common sense tells me that Wilhem tests only have 
meaning in their lab and it is false assumption to extrapolate that data 
into our individual environments and conditions. Data might be king, but 
only in the room that its sitting in when it comes to this discussion.

I managed to see some of Livicks work methodology before he removed it. 
That guy worked really hard to make sense of his own environmental 
conditions and make materials judgements based on his findings. More 
power to HIS elbow and less to those who threatened him for sharing 
those results with the rest of the community. Similarly its up to each 
of us to draw conclusions from our experience. The windowsill test is a 
good start - what's more its free to everyone! The problem with much 
discussion on this list is that at least someone always wants to be 
absolutely right, absolutely sure.

John Malcolm
Love the Light