...4x5, to be exact. Is there any way to tell how they should be processed? I would love to see what has been captured on them, if anything. I accidentally exposed one plate and it is backed with a layer of yellow material of some kind.

Thanks in advance

I rate old plates really slow. Old Ilford plates rated @ 200 originally I rate at 20 - other older plates i rate @ 6 and develop accordingly. Usually use R09 or else Aculux2. BosseB is the expert in this area.

Most common plates use speed rating systems that predate current ASA/ISO/DIN-compatible scale. If you see H&D speed, Scheiner speed, and other speed units proposed by manufacturers (such as Weston), watch out.

For units that are based on very similar measurement but differ in terms of numerical representation, the speed conversion tables may be used, but for other units like H&D, the speed is calculated from different measurements so the conversion is very approximate at best.

Perhaps I should soup it in Diafine, then, rather than muck about with times and speeds.

Are you sure they are exposed? Seems unlikely they would be exposed and undeveloped. You probably need to find a plate camera.

I got three exposed plates with a 6.5x9cm plate camera - all three holders were loaded, exposed and undeveloped. Unfortunately I didn't manage so salvage the pictures...

I also have plate cameras, plate holders, and plate adapters for international backs for just about every size except 4x5"...

No wait - I think I have one Linhof Universal film&plate holder ("mit Auswerfer") for 4x5" too!

My first plate camera (half plate) arrives today or tomorrow - very exciting, may have lots of questions...

I suspect that they are not exposed, but I would rather sacrifice the plates than risk double-exposing some piece of photo history, no matter how trivial or mundane it may be.

I am assuming the size is 4x5, since it is almost exactly the same size as my 4x5 film holders, but it could be some other size no longer in use, like 15 barleycorns x 1 hand or some such.

Now that I have these holders, I am somehow encouraged to use them. What are good resources for learning what I need to know for starting out in glass plate photograhpy?

If you want to make plates, I'll show you how in Downtown Boston when it gets cooler in the fall. But be prepared it'll take a couple of hours in the darkroom!

Besides the emulsion, you'll need a bunch of 4x5 glass.

If you have spare plate holders for 6.5 x 8.5, or a spare plate camera for 5x7, consider trading them for some plate emulsions :-)

Ryuji

I'm currently learning how to coat plates using the traditional method, with the help of a friend here. I am also designing a plate coating blade which basically uses the method that is used in commercial plants. It works fairly well, and an upgraded design model is being fabricated at the shop this week.

My friend here in Rochester achieves an average ISO of about 6 - 12 with an unfinished emulsion that he makes, and I have achived and ISO of between 25 and 50 with a similar emulsion, but with a sulfur finish and ortho sensitization.

I demonstrated this at my workshop in Montana, and hope to do the same in Sept in NYC. Since I am such a klutz so far in coating plates by the traditional method, I usually have emulsion running off my elbow. The current coating blade design is rather messy too, but that is why it is being redesigned.

I also have adhesion problems, but we are working on this.

BTW, I have a table relating several of the old film sensitivity ratings with each other. I'll try to post it when my computer is back up and running.

PE