Digital BW, The Print

>The acid in the old prints probably means that they weren't washed enough.

I don't think so.  It was more than one print, they are my prints, and I was
rather careful about thorough washing -- Perma-Wash, archival washer, etc.  

I think the problem is air-borne acids from other sources.  This is
consistent with what RIT has found.  It apparently doesn't take much to
start an acidic cascade in un-buffered fiber prints.

There is also a visible yellowing that goes from the edges to the center of
the back of the 8x10 that was in the file cabinet.  At the center the paper
is actually 0.01 units blue (c = 0.05, m = 0.05, y = 0.04).  At the very
edge the paper is 0.03 units yellow (c = 0.05, m = 0.06, y = 0.08).  At 1"
in from the edge the paper is 0.02 units yellow; at 2" in its 0.01 units
yellow; at 4" in it's finally neutral (c = y).  The pattern is the same from
all edges.  

The print was in a stack with other prints at its face and back.  The print
was made in 1986 and has been stored this way since then.  

I think the pattern is consistent with acids diffusing in from the
surrounding air in the metal cabinet, which also has some un-buffered paper
in it.  

I might add that the face of the print still looks good, although the
highlights that are near the edges are measurably more yellow than those
closer to the center.

Paul
www.PaulRoark.com
_____________________________________

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark"
<paul.roark@v...> 
wrote:
> 
> I previously noted, "The Abbey acid test pen makes just as yellow (acidic)
> marks on the back of the old fiber prints as it does on Epson Enhanced
> Matte."
> 
> I have done some further experiments that lead me to believe the fiber
paper
> in silver prints is much better than EEM.
> 
> I took the old fiber print that tested as acid as well as the EEM test
strip
> and de-acidified them with ammonia gas.  After this they both tested
> alkaline.
> 
> Starting with no acids, the question was how soon lignin in the paper
would
> produce acids that would show up as yellow with the test pen.  The test
> prints were left hanging in the air to avoid any contact with acidic
> materials.
> 
> The EEM started to show yellow (acid) in just a few hours.
> 
> It has now been a few days, and the fiber print is not showing any yellow.
> It quickly lost the purple alkaline results, but the color has stayed what
> I'd call neutral.  The test results look just like the highly-respected,
> pure cotton Arches paper test results.
> 
> So, I conclude that the paper used in the Kodak fiber-based silver print I
> tested is very good with very little if any lignin in it.  The acids I
found
> probably came from surrounding materials.  While not in contact with
acidic
> papers, the fiber prints were in a metal file drawer that also did have
some
> acidic papers in it.  The lesson may be to store prints in buffered boxes
--
> which is the standard recommendations for B&W prints, I believe.  I
suspect
> buffered interleaving would also be a good move for B&W (not color, as I
> understand it).  Even acidic papers in the same file drawer may be a
source
> of danger to silver prints.
> 
> Paul
> www.PaulRoark.com 
> ___________________________________
> 
> 
> 
> -----Original Message-----
> From: Paul Roark [mailto:paul.roark@v...] 
> Sent: Friday, March 05, 2004 8:32 PM
> To: DigitalB&WPrint
> Subject: [Digital BW] Acidic Silver Prints?
> 
> I just read that the paper used in making traditional photo fiber-based
> prints is actually purified wood pulp.  Lignin in wood is the main reason
it
> has a tendency to become acidic even if no acids were used in processing.
> Cotton has no lignin, which is the hard substance that allows trees to be
> tall.  Thus cotton - almost pure cellulose - is considered a much better
> (but more expensive) base for paper.
> 
>  
> 
> I've heard that while lignin can be reduced substantially in wood-based
> papers, it can never be 100% removed.  So, for archival wood-based paper,
> the trick is to reduce the lignin to less than 1% and then have 2% buffer
> (usually calcium carbonate) in the paper to offset the residual lignin as
it
> breaks down and forms acids.   The buffers absorb the acids before they
can
> do any damage to the cellulose.
> 
>  
> 
> Unfortunately, wet prints that go through an acid stop bath can't have
> buffers, it appears.
> 
>  
> 
> (I've heard that a small amount of residual fix left in the print actually
> helps preserve the print.  Is this because it can act as a buffer?)
> 
>  
> 
> I've also heard that the air &/or airborne gases or pollutants can cause
an
> acidic cascade in even pure cellulose, cotton paper unless it is buffered.
> 
>  
> 
> So, it occurred to me to test some of my old fiber-based silver prints
that
> had never been mounted.
> 
>  
> 
> I hate to say it, but the Abbey acid test pen makes just as yellow
(acidic)
> marks on the back of the old fiber prints as it does on Epson Enhanced
> Matte.
> 
>  
> 
> (Most of my silver prints are mounted on buffered mat board.  Hopefully
the
> buffered mount board is helping to absorb some of the acids.  I'm going to
> be looking for buffered interleaving sheets for the rest.)
> 
>  
> 
> I wonder if an EEM print with a buffer sprayed on the back or mounted on
> buffered board would last as long as an Ansel Adams print?  It now seems
> like a much closer question than I would have guessed.
> 
>  
> 
> Paul
> 
> www.PaulRoark.com <http://www.paulroark.com/>  
> 
> 
> 
> [Non-text portions of this message have been removed]
> 
> 
> 
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