Digital BW, The Print

Hello All,

A big problem with these kinds of discussions is that there are so
many broad assumptions underlying the questions and statements.  For
example, there is the assumption that "OBAs make paper whiter", and
from that we get "all papers with OBAs will yellow with time".  In
fact, neither of these is necessarily true.  There are different kinds
of OBAs and they can have different effects and different longevity. 
HPR has OBAs in the coating but it is not a white paper.  It's bright,
but not white.  "White" and "bright" are not the same thing.

Diana York of Hawk Mtn Paper has stated (at least once in this forum
and several times during phone conversations with me when I was
researching my "Great Paper Chase" article) that for their white
papers they use a paper base that is already white to begin with and
doesn't need additional whitening.  Indeed, from my own experience
with Condor BW (very bright and white), when I compared a fresh sheet
with a print that had been hanging here unprotected for over a year, I
could tell that it had lost a bit of brightness, but had not yellowed.  

In addition, there are different kinds of coatings.  Some are clear
and the color we see is the paper color, and some are opaque and what
we see is the coating color.  All of these things affect what kinds of
OBAs are used, if any.

So there are issues of how much OBA is used, what type, and whether
it's in the paper, the coating, or both.  Hahnemuhle has stated that
the amount of OBAs in HPR (in the coating only) is very small.  I've
compared fresh HPR sheets with prints that are several years old, and
like Condor, are slightly less bright but not more yellow.  

When I was researching the article I had a number of phone
conversations and email correspondence with several paper vendors
about various subjects, including OBAs.  It's too much to repeat here,
but a summary of it (including a complete statement from Diana York) 
can be read in more detail in the Paper Chase article (#5 at the link
below - go to the Contents and look for the link to the OBA section).

Further, (this seems to need repeating now and then), I've got
darkroom prints from 20 years ago on papers such as Oriental Seagull
that are alpha cellulose OBA papers that are still very bright and
very white.

The point of all this is that it's a mistake to assume that OBAs are
always a kiss of doom and that all OBA containing papers will yellow,
even ones that are truly white papers. I know this makes everything
less convenient, but each paper needs to be evaluated individually.


Regards,
Clayton


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