Help with old dry plates (speed, processing)

Hello all,

I was given some old dry plates and I can't seem to find any information about their ASA speed characteristics (or equivalents), nor about how I should develop them.

Here is a list of the packs, typed from the boxes:

Gevaert Process Extra Ortho O5 Antihalo 6x9
Gevaert Replica Antihalo 23 6x9
Gevaert Gevaplan 30 Panchromatic 6x9
Agfa Diapositiv Platten 8,5x8,5
Agfa Isochrom Orthocromatic 9x12

And here is a picture:

http://www.aistiharha.fi/glassplatten.jpg

Is there someone here who has knowledge about these films, and their processing? I am fluent with large format film development, but have not developed glass negatives before.

Especially the diapositiv (colour slide) plates are interesting, I guess they use the Agfacolor process? I have an old book describing the process for 35mm film, does anyone know whether the process was same with plates?

I'm trying to find plate holders and shoot these with my Toyo 45A.

Best regards,

Timo Harjunen
Helsinki, Finland

Gevapan is panchromatic - IIRC they named the films by Scheiner grades, so 30 may have been around ISO 64-80. Isochrom can be considered the direct ancestor of Agfaortho 25 - made for something like seventy years its speed increased over time from ISO 6 to 25.

O5 and Replica probably are process plates. "Diapositiv Platten" are not colour, but black and white slide duplicating plates, presumably the slowest of the bunch with a sensitivity in the same range and spectrum as paper.

YMMV 50 years later - the plates probably have grown fog and lost sensitivity.

As far as development goes, dilute Rodinal might squeeze something useful out of the line plates, at very low sensitity. The others might fare best in HC-110 or D-76/ID-11 with some extra benzotriazole anti-fogging added.

Thank you for these guidelines! It's good to have a starting point from where to start bracketing.

I was thinking about using HC-110 as the developer, I've had good results with it in the past, I recently developed a roll film expired in 1966 with fairly good results.

I'll start experimenting with the plates as soon as we get rid of a metre or so of snow first.

BR,

Timo

http://newlightfarmer.blogspot.com/2...1_archive.html
Scroll down to see a 8x10 glass plate wedge strip test shot on old plate film and processed in Pyro.

Quote:

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Originally Posted by Michael Carter

http://newlightfarmer.blogspot.com/2...1_archive.html
Scroll down to see a 8x10 glass plate wedge strip test shot on old plate film and processed in Pyro.

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Hi Michael,

I had a look at your blog and it seems to be a great font of information about dry plates. I couldn't find a "comments" option there so I'm writting here in hope you (or others) can help me.

I recently got a box of Ilford dry plates to use on my Voigtlander but I can't figure it out what's the ISO. I'm posting the picture in hope someone know...

It also have the P.P.10. on the side of the box.

I'm thinking of using Rodinal for processing, any advice regarding time ?

Many thanks !

Don't know what Ilford Speed Group 5 was, but 28° will be (European) Scheiner - i.e. ISO 18/50. You'll have to test how much is left of it. Rodinal is far from being the best ready made developer for old film, and moreover a film that will need prolonged testing. - HC-110 is more well behaved, and has very similar development times for most films in one sensitivity range, so you might get away with one test plate or two.

Thanks Sevo for your advice.
What's the best developer for this kind of film you'd say ?

I did process a 1964 Ilford 35mm with Rodinal and it was a success... I remember I compensate a few stops on the camera and developing time, but I guess dry plates are older and is a totally different emulsion...

As I said, HC-110 is widely considered the best ready-made developer for massively expired film, as it already has anti-fogging integrated and will develop many films to a reasonable result with one standard time. Other developers (with added anti-fogging agent) may deliver a better result if you have plenty of material for trial and error, but if you only have one or two attempts, HC-110 is most likely to deliver a usable result.

The problem with HC-110 is that it's unclear which dilution to use, and what time to use since directions are unavailable. I would suggest instead to use Diafine. Regardless of what film (or plate) you have you develop everything the same, 3 minutes in each of the two baths (A and B). I have used Diafine on many different types of Kodak glass plates (Metalographic plates, Type 33 plates, Tri-X plates, Ilford HP-3 plates), as well as on such things as Kodak Electron Image film, various X-ray films, Kodalith, etc. I have done landscape photography with all of these with good results. The problem is usually to find an ASA speed by trial and error.

Quote:

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Originally Posted by rjmeyer314

The problem with HC-110 is that it's unclear which dilution to use, and what time to use since directions are unavailable.

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The standard 5 min in Dil.B (1+31) at 20°C are pretty close to the best value for just about every slow film. Two bath developers are even easier, but their strongly compensating properties tend to amplify fogging, and leave no option to push the film for a higher contrast and speed if it should have gone soft and slow (massively expired film more often drifts that way than the opposite).