Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Mark Savoia <mark@...> wrote:
>
> Gee, I have some 30 year old RC prints and no brown. They might have  
> not been fixed and washed enough. Not that that should take more then  
> a few minutes. Might be the environment they were stored in?
> 
> Mark
> http://www.stillrivereditions.com
> 
> On Dec 21, 2009, at 1:52 PM, Jules wrote:
> 
> > The RC ones often turned brown after a couple of years.
>


Yes, I too, have some RC prints I made over 25 years ago, framed and always having been on display, and they are still crack free with only subtle yellowing in the media white point. This subtle yellowing has to do with the color coupler technology of that era. After "perfect" processing, these color coupling compounds that form the dyes in the first place still remain, and eventually yellow.  That's not an RC base issue as much as it it a chromogenic color print technology issue. Moreover, when you see very strong discoloration such as brown or grayish-brown media white, this is also not an RC base issue. It's exhausted bleach-fix whereby the processed silver (which creates oxidized developing compounds to trigger the color coupler-dye formation) is inadequately bleached back to silver halide and the silver halide inadequately removed by the fixer. Again, not really an RC base issue.  The RC base problem is largely cracking in the polyethylene layer due to the TiO2 whitening agent forming free radicals upon extended exposure to low light levels. The cracking is eventually going to be more severe than we see in traditional fiber prints, but traditional fiber prints are also prone to cracking in the gelatin layers if exposed to strong seasonal cycles of high to low Relative humidity, i.e., the kind of cycling that is largely unavoidable in buildings situated in cold winter climates combined with humid summer climates.

Mark
http://www/aardenburg-imaging.com