Digital BW, The Print

Hello Michel,

> <<..... For me, this is an acceptable amount of "burn off"
> and it's a really nice Paper.....>>
> 
>Clayton, by "burn off" do you mean a loss evenly spread all over the
sheet surface ? 

Yes, there was an overall uniform slight loss of brightness and slight
warming of paper color (by slight I mean _very_ slight).

I want to add some more comments about OBAs, to add to my previous
post (BTW, in that, I mentioned "P1" and "P2" - I should have said
"W1" and "W2", referring to the whiteness scale used in the article. 
I was thinking "paper" color...

I have not yet found a precise definition of what "burn off" actually
means.  Lots of people use the term without really knowing what it
means, including myself (I think we all have the right idea, but I
mean a precise scientific measureable definition).  Even Diana York,
when I asked her directly, couldn't tell me exactly what kinds were in
their coatings, how long they would last, or to what degree the
effects of burnoff would be.  Those web links were the most scientific
discussions of OBA I've yet found.  According to the second one, even
the term OBA is not scientifically precise:

"Optical brightening agent is used colloquially, but is not precise,
because brightness is defined for a small band of wavelengths only."

Neither of these links uses the term "burn off" either.  The closest
one comes to that subject was in the paragraph about "lightfastness".
 This brief mention is the most scientific treatment of the subject
I've seen so far.

From what I gather so far, there are many different kinds of OBAs,
they can have many different effects, and the newer ones are more
stable and long lasting.  As Diana pointed out, "Whiteness" and
"Brightness" are not necessarily the same thing.  Apparently, some
OBAs enhance one or the other or both.  This shows up in the papers. 
For example, Photo Rag is brighter, but not whiter, than Aurora Art
(in the article, PR is rated at W4 and Aurora is W2).  Premier Fine
Art (W6) supposedly has no OBAs but it's actually quite bright (bright
cream, not bright white).  So there's more going on here than we
understand.

The point of all this is that to merely state that a paper has OBAs
doesn't tell us enough to really know how the paper will perform.  We
don't know whether whiteness or brightness will be affected, to what
degree, or over what time period.  So I guess we need to collect
anecdotal evidence over time before we can begin to know what to
expect.  However, I've been in this forum over three years now and
can't recall ever seeing a "for sure" report of burn off.  Only
warnings that prints on OBA paper "might" eventually turn as yellow as
the non OBA paper is to begin with.  But that hasn't been my
experience so far.  My recent observation of the Condor prints was my
first real world experience that I'm confident is attributible to OBA
burn off.  I've got some prints on PR 188 unprotected on a bulletin
board under almost constant light for nearly three years.  The old MIS
FS ink has warmed and faded but the paper is still bright.  So how
long before burn off occurs on PR?



>Generally speaking I never noticed any lost in brightness per say 
>all over the print but get a yellowish hue unevenly spread along 
>the edges.

I haven't experienced that.  There have been lots of reports of
yellowing in reaction to certain chemical agents in packaging and
tape, etc, and often edge yellowing is reportedly due to prints being
stacked in a drawer or box, so only the edges are exposed
to...whatever.



>BTW, thanks for your article and the great work you have done there, 
>waiting to see the update.

You're welcome.  I'm happy to contribute something in return for all
I've received in this forum.


Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm