Digital BW, The Print

Guess this thread is coming to a close... it's been very helpful, thanks to you all.

Paul

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Mark" <mark@...> wrote:
>
> 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Seth Rossman <seth@> wrote:
> 
> > However, I question the LOC's statement.  RCs (in a silver-based 
> > spectrum) are much easier to vacate hypo and acids than from paper-based 
> > prints, though both are doable.
> 
> Early RC (1970s) paper, color and B&W even more so, got a bad reputation because the manufacturers missed a new form of deterioration caused by their switch to TiO2 whitening agents in place of Baryta. The TIO2 was actually light sensitive, generating free-radicals that then caused peroxide formation which then caused premature brittleness and cracking in the RC (polyethylene) layer plus serious silver tarnishing in the B&W RC prints. The products were greatly improved as manufacturers learned to add anti-oxidants and use other structural forms of TiO2.  Nevertheless, the bad reputation had been earned early on, and that's why you see restrictions on it's use for "archival" documentation.  Incidentally, this light-heat-humidity induced RC B&W tarnishing reaction is very difficult to replicate in the laboratory, so the ISO committee working on archival recommendations for RC Paper failed over a 20+ year effort to ever come up with a standard.  Another reason for archivists not accepting this type of material (when they can get away with it).  And of course, by now RC silver halide papers are a vanishing breed, so the need for an ISO processing standard has become a moot point.
> 
> 
> best,
> Mark
> http://www.aardenburg-imaging.com
>