Digital BW, The Print

>>So of the two Hahnemuhle papers, the one with OBAs outlasts the  
>>"purer" paper.
>>Am I misunderstanding something?

>I don't think the OBAs is the significant difference between the
>papers.  I've had Harman FB Al in a south facing window since last
>summer and the paper base has moved from cool to neutral but doesn't
>seem to have other negative effects.

In addition, there are different types of OBAs.  We use the term
broadly, but when I did some research on the subject for an article
(#5 at the link below) it was pointed out to me that OBA technology is
improving along with everything else and newer ones are much better. 
There is no way for us to know what or how many types are used in any
given paper, in what combination, whether they are in the paper, the
coating, or both, and in what quantities - paper makers keep their
formulas secret.  Just saying a paper has or doesn't have OBAs doesn't
give us enough information.

Not only that, but we can't always believe what the paper makers say.
During my research it turned up that a popular paper by a major maker,
advertised as having no OBAs, actually had "small" amounts in the
paper "to ensure uniformity of color" across production batches, but
"not enough to affect print longevity".  As a result of this discovery
a major vendor who was selling a repackaged version of the paper
changed the wording on their web site (they later discontinued the
paper, although I don't know if the OBA issue had anything to do with
that).

I know this probably muddies the waters for us, but there it is.  We
should beware of over-simplifying the subject.  If we accept W's tests
as valid then perhaps they should be the basis of choosing our papers.

For example, I use VFA a lot with K3/ABW.  According to W, VFA has
"some" OBAs (I suppose that means a small amount, other papers are
listed as "yes" or "no").  Here are his results for this combination:

Unprotected > 112
Glass > 115
UV Glass > 125
Dark > 200

...and with the new K3-Vivid Magenta/ABW
UV Glass > 400

That's good enough for me.  I've been doing a direct sunlight torture
test on a VFA print for several months and hope to report some results
soon.  Might be interesting...

Regards,
Clayton


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