Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Diana York" <diana@h...> 
wrote:
> A lot of that will depend on both the amount of OBA's (i.e. how much OBA's are 
being used to whiten the coating/paper)
> and the whiteness of the base sheet. If the coating without OBA's is still very white, 
and the base sheet is very white,
> any breakdown of the OBA's should not cause appreciable yellowing. We are 
developing coatings which are OBA free and
> still very close in whiteness to the OBA containing coatings we have used in the 
past. IMO yellowing is caused more
> often by a chemical reaction - the paper touching something acidic or otherwise 
chemically reacting with the coating.

Isn't it possible that the degraded form of the OBA is itself yellowish? This could be a 
cause of eventual yellowing--even if the paper itself is reasonably white (before 
addition of an OBA).

Phil