Digital BW, The Print

After reading some of the recommendations about Mr. Livick's assessments of Wilhelm labs I 
was amazed...at the amount of disinformation.  To start, Livick talks lumens as if lumens 
defined light; They do not.
The light spectrum is composed of any frequencies ranging from the UV to the infrared. 
The UV portion of the spectrum is highly chemically active and its destructive powers 
cause the chemical changes that bring about the fading of prints.  Other factors modify 
the end results such as humidity.

A large industry has developed out of the need to know in a reasonable time the effects of 
light and most of it revolves around increasing the dosage of destructive  frequencies. 
Machines ranging from quite expensive Xenon arc and other exotic light sources to UV 
machines are found in paint and textile labs. More recently, (the last 15 years or so) the 
so called Quick UV machine has become the darling of many interested in studying fade 
resistance.  UV fluorescents power the QUV machine.  These emit a considerable amount of 
destructive UV so much so that one minute exposure of some of these tubes would give you a 
sunburn.  The problem in trying to match sunlight is problematic.  Which sunlight? The one 
on a tropical island at the equator?  The one at a mountain at the equator? The one at a 
northern latitude where the sun's rays strike the earth at a glancing angle during 1/2 the 
year?  The one in cloudy or misty Vancouver BC?
To my knowledge no quick machine delivers results that are exactly the same as those from 
the sun because among other things sunlight is not a constant quantitatively or 
quantitatively at least on the earth's surface.

You can rest assured that the makers of these machines know their physics and the 
intensity of the actinic rays their machines can deliver and how that compares to hours of 
sunlight at a given latitude at a given time of the year.  Mr. Wilhelm most likely does 
too, he has been in this business for many years.  It must be grating to these people that 
someone gets in the web and posts such stuff and that many people believe it.

That said, based on my own experience in doing accelerated tests via machines and actual 
exposures, no machine matches every natural exposure.  Mr. Wilhelm has a product to sell. 
That does not make him wrong.  Mr. Livick has none to sell (in the fade testing area), 
that does not make him right. Perhaps if he did he would have to learn the basics.  OK so 
can you trust Epson's /Wilhelm's numbers on longevity?  A very qualified yes.  When 
Wilhelm's asserts that ultrachrome inks last longer than dye based inks I give him an 
unqualified yes.  Is it 70 years? 60 years?  50 years, 40 years?  hum.....
Julio Fernandez


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