Kodak Super-Panchro P.1200 plates

[Stan160]

I've just bought two boxes of 12 of these plates, one box is stamped with a date in 1965 - presumably the expiry date.

There's a thread (there was a url link here which no longer exists) that gives the speed as 200, and recommended developers and times of Press DK60a, 5min; Commercial DK60a, 4 min and DK50 5 1/2 min.
I'm no stranger to mixing developer from raw chemicals, and sure the formula for these developers is around here somewhere, but these are presumably figures for fresh plates, not ones nearly 45 years past expiry.

Has anyone got experience or advice to offer about modifying the given speed and developement to account for aging. Obviously a lot depends on storage conditions, but with only 24 plates I would like to minimise wastage in coming up with the right exposure and development times.

Thanks,
Ian

 

[Michael W]

You should be able to get it pretty close after 2 or 3 plates.
Based on my experience I'd make the first exposure at 12 ISO, based on the assumption it's lost 3 or 4 stops of speed.
I get good results in Rodinal & would dev the first plate at 1:100 for about 15 minutes. If you get high fog levels you can look into mixing some benzotriazole fog reducer for the next plate.
From the first plate you can assess the shadow detail for EI & the highlights for development & adjust from there for the next plate. Hopefully the first plate is close enough to being right that you only need to make minor adjustments.

Some people suggest HC-110 for old emulsions as it supposedly has some anti-fog agent incorporated, however in my testing I got much more fog with HC-110 than I did with Rodinal & benzotriazole.

Pay attention when unwrapping the plates & loading into your plate holders. Glass plates are not marked like film is as to which is the emulsion side. Generally they are packed in pairs, emulsion to emulsion, so it's a good idea to load the holders in multiples of two. I'd hate to have a single plate & try to determine which is the emulsion side.

 

[Stan160]

Thanks Goldie, some very useful info to get me in the ballpark. I've got a bottle of Rodinal, and some Benzotriazole, so I'm all set once the plates arrive.
Ian