Digital BW, The Print

Ernst,

Ammonia is very alkaline, with a pH of close to 12.  It is used in a number
of de-acidification procedures.  See, for example, 

http://www.kb.nl/kb/resources/frameset_kb.html?/kb/cons/leather/chapter5.htm
l

The problem they note there is that some dyes and pigments might be
discolored.  Whether the images we deal with would be so affected needs to
be tested.   

The reactions in the URL you cited seem to require UV light and pollutants
in the air that causes a reaction that forms acidic NOx.

Again, however, I'm not a chemist.  In my experiments what I see is that
acidic paper put in a bag with a cap half full of ammonia becomes alkaline
very quickly, according to my acid test pen.

As to the fade testing of Ultima, the first sample was the wrong paper.
I've just received the correct paper and will try to get a comparative fade
test going early next week.  Then it'll be another month before it runs long
enough to start seeing any significant results.

Paul
www.PaulRoark.com 

____________________________

-----Original Message-----
From: Ernst Dinkla [mailto:E.Dinkla@...] 
Sent: Thursday, March 11, 2004 11:16 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] Acidic Silver Prints? -- Update

Paul Roark wrote:


> With inkjet prints there have been stories from Florida of very rapid
> deterioration of Epson Enhanced Matte prints.  Presumably the heat and
> humidity in Florida accelerates the acidic attack on the paper. 

> I think if I had an important print that was dry mounted on acidic board
I'd
> first de-acidify it in a bag with ammonia for about 20 minutes.  Then I'd
> use the Wei To product on the back and hope that the dry-mount tissue
> stopped the product from reaching the print. 

Remembering some ecological disputes about cow dung creating 
ammoniac gases in the air and the resultant acids when ammoniac 
gases are exposed to light I wonder whether that treatment will 
no worsen the archival qualities. Could be just a local Dutch 
problem of course :-) Similar thoughts are expressed here:

http://www.usask.ca/lists/alt-photo-process/1996/alt96b/0757.html

I think ammonia only reacts with UV light but I could be wrong.

I think buffering in the paper itself is the most important thing.

BTW, Paul any sign of fading on the Kodak Ultima paper yet ?

Ernst



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