Digital BW, The Print

john dean wrote:


> Wilhelm's figures could very well be off by 50%, they have 
> been in the past.

I'm just taking an atopical diversion here, but since archival 
properties get discussed here fairly obsessively, I might propose that 
Wilhelm's numbers are perhaps best understood as unitless. I know that 
the unit "years" gets attached to the results, but I'd rather interpret 
this to mean "on order of unit years."

I think what Wilhelm provides are (a) testing with a consistent 
methodology resulting in comparable results from test to test, and (b) 
testing in which inconsistent methodology is documented. The value of 
this (at least to those who seek a genuine understanding of the value of 
the tests) is hard to emphasize strongly enough. I'm definitely showing 
my geek genes here, but I'd much rather have a paper in which everything 
is described in tedious detail, with measurements, and with math; than I 
would read hand-waving about how things 'looked' by eye on an 
artificially aged print, to a tester who also can't describe the 
emission spectrum of the lights used to age it. The former is of far 
more value than the unit-bound results (the longevity or permanence 
ratings given in years) alone would suggest.

Now, back to your regularly-scheduled varnish debate....

--
Jeff Medkeff
Eagle River, Alaska