Kentona pepper fogging in fresh lith developer..?

[Jersey Vic]

Yesterday I could not make a single Kentona lith print without some ugly pepper fogging in the midtones. Big ugly grain blotches..some with tentacles.

After 3 prints and 1.5 Hour I switched to Varycon which is very nice, even better for some images and no fogging.

What gives? Kentona is certainly a beautiful paper for this process but at 20 minutes + a print and $1.25 a sheet I don't have the time or money to spare.

Thanks

Victor

 

[juan]

As the temperature went up this summer, I found Kentona fogging. After emailing Kentmere, I began to experiment with adding KBr and benzotriazole to my developer. This is for traditional prints in amidol. Maybe you need more restrainer in your developer, too.
juan

 

[Jersey Vic]

Hi Juan. Come to think of it yesterday was my 1st 'hot' weather lith session with Kentona.
I referred to THE lith printing book and it does go over KBr solution for old-er developer but the warmth factor is news to me.
Thanks
Victor

 

[Lowell Huff]

"pepper fogging" with lith chemistry is do to over development or low levels of sulfite in the developer.

 

[juan]

Kbr produces warmer prints - benzotirazole colder. I experimented until I found a balance I like. I made up 10% KBr solution and 1% benzotriazole. I don't believe there's a right and wrong here - just get enough to stop the fogging and get a balance that produces the tone you like.
juan

 

[psvensson]

I thought additional sulfite was the standard cure for pepper fogging?

 

[Jersey Vic]

I thought additional sulfite was the standard cure for pepper fogging?

I agree but I thought pepper fogging was due to exhausting developer..?

By the way-today it worked perfectly with all conditions the same as yesterday...

 

[tim rudman]

Peter and Vic, you are both right.
Exhausted developer = lower sulphite levels = pepper fogging in susceptible papers.
As you put more prints through, the sulphite levels fall and the bromide levels rise. (& HQ falls, pH shifts etc - as in the book)
Extra sulphite therefore is a first measure for PF, with care as too much will inhibit your infectious development.

PF was mostly a major problem with the later batches of Sterling Lith paper, but is really not usually too much of a problem with most current papers - unless provoked by very high dilutions, very used dev, high temp etc. (I know you occasionally see it, but it is exceedingly minor compared to the Sterling PF phenomenum).

KBr is a useful tool for anti fogging in general developing. But old highly dilute lith dev has lots of KBr already from the previous papers passed through it, so better not to add more at that point - cautiously address falling sulphite levels first.
KBr is more useful in lith printing when added to fresh dev as a restrainer, and there it tends to cool off the image ( or at least the lower values ) rather than warm up, as you get the fine grain (warm tone) silver restrained and the larger grain silver eventually breaks through via infectious development, and is cold toned. The warmer tones come in later - or even via another developer. That is the rationale in 2-bath strong/weak lith dev processes or lith glycine as in Moersch's Polychrome kit.
Tim