Paper mount archivality

[P3D John Bercovitz <bercov@xxxxxxxxxxx>]

Everyone knows there are certain plastics which are incompatible 
with negatives so you best not store your negs in sleeves made of 
those plastics.  (BTW, does anyone know what the specific failure 
mode is?)  And then there are vendors like Light Impressions that 
sell archival paper.  I think I've heard that non-archival paper 
has lignin (wood fibers) in it and that lignin breaks down into an
acid which attacks the paper.  And that's why a 400 year old book 
printed on rag looks better than a five year old paperback printed
on wood pulp.  

I understand that the paper disintegrates but does the acid also 
attack the transparencies?  If so, what is the failure mode?  What 
does the transparency look like after acid attack?

Can paper be tested to see if it's archival or not?  Or do you 
just have to wait five or twenty years to find out?  I guess you 
can't test for acid until the lignin breaks down.  Can you 
accelerate the breakdown of the lignin into acid?  How would you 
test for acid?  Grind up a specific weight of the paper and put it 
in a specific volume of water and stick litmus paper in it?

Thanks,
John B


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