Digital BW, The Print

On 03/01/2012 12:29 PM, Seth Rossman wrote:

> First, PVA's are generally considered a very stable adhesive in the
> conservation and museum community. If they are now in question it opens
> a whole new area--beyond photography.
>
> Second, there are plastics and there are plastics. Any that give off
> "plasticizers" will be an issue.

In relation with OBA the PVA is just one of the possible causes, I did 
not mention water next to the glycol and glycerol, there are also 
wetting agents etc in ink medium. All of the speculative as I do not 
have a clue. PVAs are quite inert as I understand it like gelatines are. 
OBAs will be the first problem in conservation anywhere, what other 
chemicals bring to that problem is the next question.

Polyethylene is usually the plastic associated with Photo - RC papers. 
Its flexiblilty depends mainly on the polymer structure, high density 
quality is the flexible one, low density is used for large blow molded 
tanks etc. Plasticizers are more used for PVC/Vinyl/Cellulose Acetate 
plastics if I recall it correctly. Degradation of polyethylene outdoors 
is caused mainly by UV rays. Problems with RC papers in the past like 
cracking, loss of the bond to the paper base, were caused by certain 
types of TiO2 whitening agents mixed in the polyethylene front barrier, 
the back layer was usually transparent and remained unaffected. Today's 
RC papers are much different but should be tested on those aspects in 
relation to the colorants longevity. There is not much sense in testing 
beyond the colorants lifetime like there is no sense in testing the 
colorants beyond the paper's structural lifetime.

-- 
Met vriendelijke groeten,   Ernst

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