Excellent post, Martin!
the only thing i would add is that the "amount" of buffering agents
tend to affect the archivalness of a paper. Libary of Congress
standards indicate that they consider an archival paper to have not
more than 3-5% of fillers (fillers include buffering agents like
CaCO3, pigments like titanium dioxide or silica) by weight. (my
memory may be off here, but i think i posted the LoC website in an
earlier post and Martin bookmarked it in the Files section of this
list.
Fillers are measured by the amount of ash resulting by burning the
paper.
Museo contains 2.8-3.3% filler or buffering agent (Calcium carbonate
in Museo's case; this is the most common alkaline buffering agent--
arches, etc have used this for centuries.) We have tested some
papers--internally--with an ash content as high as 10%.
hope this helps,
robert rex
crane & co
--- In DigitalBlackandWhiteThePrint@y..., "Martin Wesley"
<mwesley250@e...> wrote:
> --- In DigitalBlackandWhiteThePrint@y..., SKID Photography
> <skid@b...> wrote:
>
> (snip)
> >
> > But I must take issue with the 'acid pen' and the 'buffered'
pspers
> statement.
> >
> > I still maintain that buffering has, so far, shown itself to be
> detrimental to inkjet inks and also, that if
> > the paper has an acid component (using wood pulp instead of
cotton,
> or 'rag' fibers') the buffering agents
> > will be overwhelmed in the long run and self destruct.
>
> Harvey,
>
> There are many qualities that determine a good paper. One is the pH
> of the paper as a measure of acid content which is easy to check
with
> the pH test pens. Another is that the paper be lignin free, which
is
> not so easy to measure. Lignin is the component in wood pulp papers
> that breakdown into acid compounds and cause yellowing. Quality
wood
> pulp papers are made that are lignin-free and are the equal to rag
or
> cotton paper in permanence. The lignin free wood pulp papers are
> preferred in many applications as there are stronger than rag
papers.
>
> Buffering is added to lignin free, acid free papers to form an
> alkaline reserve to protect them from environmental conditions that
> would cause the papers to become acidic.
>
> Quality papers are made with out buffering that will last as long
as
> the buffered papers if not subjected to outside sources of acid.
>
> Non-buffered papers are required for use with dye based materials
as
> color dyes will react badly with the buffering agents. Dyed
textiles,
> dye transfer prints and I imagine dye-based inkjet prints should
not
> be used on buffered paper to ensure image permanence. I believe
that
> the "Archival" in EAM has to do with image permanence and that the
> paper was designed to work with the Epson 2000P.
>
> A high quality lignin-free, acid-free paper without buffering will
> have a pH of about 5.5 to 6.0 and will test acid with a pH test
pen.
> This is the situation with silver fiber paper, which will test
right
> on the threshold of the pen. EAM tests on the acid side of the
> threshold but is probably an acid-free paper in its manufacture.
From
> its stiffness I would be very surprised if EAM was not a wood pulp
> paper.
>
> While I agree with your point about non-buffered papers and image
> permanence for dye based ink sets, I think that buffered papers are
a
> better way to go with the carbon pigment quads. A lot of fade
testing
> has been done with the carbon pigment inks on a number of papers
and
> there does not appear to be any relationship between the buffering
> and image permanence from the information we have. So unless you
know
> that the buffering will effect image permanence, you are better off
> going with the buffered papers that offer protection from
> environmental contamination.
>
> Also keep in mind that the vast majority of art papers being used
for
> inkjet printing is buffered. Hahnemule, Crane, Legion, Brightcube,
> Hawk Mountain, etc. are all buffered papers. If you want non-
buffered
> papers the choices are pretty limited.
>
> The other quality of a good paper to consider is the presence of
> optical brightening agents of OBA's. These add to the image range
but
> will yellow with time. The yellowing of EAM in Paul's fade tests is
> probably due entirely to the decay of the OBA. Crane's Museo, which
> has no OBA's, did not yellow. Other papers use varying amounts and
> yellow to different degrees. The decay of the OBA's will be in
direct
> proportion to the amount of UV they are exposed to.
>
> There is a huge amount of information on paper permanence. If you
> check the Files and Bookmarks sections there are some links.
> >
> > Those old photos were, in general, made on rag papers that were
> acid free to start with, and then, over time
> > they have encountered acids in the atmosphere, causing the
> degradations.
>
> You could see marked differences from different time periods. The
> 1840's paper was still white but the papers from the late 1800's
and
> into the early 1900's were in bad shape. If it was strictly
> environmental, then some should have been ok and others not, but
they
> all showed decay. It was not so much that they were yellowed but
that
> they had turned dark chipboard gray, which I suspect was caused by
> the use of wood pulp in the paper. Whatever the reason it was very
> sad to see.
>
> >
> > It is my feeling that if one wants long term stability (like on
the
> old photos) one should use rag papers,
> > which have slight amounts of buffering agents in them...hopefully
> enough to neutralize acid atmosphere over
> > time, but not enough to degrade the inks...Unlike wood pulp
papers
Show quoted textHide quoted text
> that achieve ph neutrality only because of
> > large amounts of buffering agents.
>
> Rag is a good choice but like I said you can make a high quality,
> lignin-free, pH neutral wood pulp paper that is the equal to rag.
>
> Martin Wesley
>
> (snip)