What happened here?

First - apologies in advance if I put this in the wrong place! Still learning this forum besides the gallery and classifieds (thank you all for the inspiration and gear)

This is a J. Lane speed plate ASA 25. Box is a few years old but I just shot and developed this one.

The non emulsion side of the glass plate has a strange leaflike looking substance stuck on it. Emulsion side looks good.

Any idea what caused this or how can I clear it off, if at all? Is it the antihalation layer? (Do these have one?)

I noticed this as soon as it was out of the fix. I thought maybe the hypoclearing would clear but nope.

I’m still new to these and 4x5 so forgive any rookie errors, such as not getting the plate holder all the way down and losing a centimeter of the image

I would contact pictoriographica and ask them directly, with pics.

I’ve not used Lane dry plates and have no idea what the material on the back side might be.

Since this is on the non-emulsion side, you might find a suitable solvent that would remove the unwanted material. Try a sparing amount of various solvents, being meticulous to not get any of it on the emulsion side. Acetone or lacquer thinner are possible candidates.

Careful and gentle use of a single-edge razor blade might separate the material from the glass.

I expect this is due to the manual coating/pouring process that I believe is used to make these plates. In that process, a droplet of emulsion/gelatin can 'drop off' the plate and pull itself along the backside due to capillary action if the plate was held/contacted by something (e.g. a gloved hand) during pouring. Apparently this was not cleaned off, leaving developable silver halide on the backside of the plate.

Ian C said:

you might find a suitable solvent that would remove the unwanted material.

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I'd use a little chlorox bleach on a pad of some kind and wipe it off. No razor; it might scratch the glass. Chlorox will soften the gelatin, making it effectively disintegrate. Don't get it on the front side of the plate as the damage will be irreversible.

I vaguely recall the issue of emulsion making its way to the backside of the plate being discussed/acknowledge a few years ago by Jason Lane, perhaps even here on Photrio.

I recently purchased some Lane plates, and the instructions say to do what @koraks said above....
The plates are hand coated, sometimes emulsion makes its way to the base side.

Thank you kindly everyone! @koraks that worked perfectly. I used a bit of 70% isopropyl alcohol, a Q-Tip and patience. Et voilà it is gone with the emulsion side still intact.

I just received a fresh couple of boxes of the new batch so I’m excited to keep playing with these.

Ah, great job! (And also on correctly spelling 'voilà; , haha!)
Good to hear everything's OK now, have fun with the plates!

koraks said:

Ah, great job! (And also on correctly spelling 'voilà; , haha!)
Good to hear everything's OK now, have fun with the plates!

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Ha! It irks me to not get the accent when it is right there on the keyboard.

The next mystery is I seem to have accidentally made an ambrotype! I thought these happened with slight underdevelopment? But I overdeveloped and overexposed. (I had been having trouble getting anything on the plates the last few tries, so with a dull but snowy scene and slightly outdated plates, I went with over over.)

Any sense what happened this time?

I think these are so, so cool I’m happy to have accidentally made one… but would prefer to make them on purpose.

Thin silver images generally make good ambrotypes, which would indeed suggest underdevelopment, but transmission density on that second photo looks fine. If it scans & prints as desired, don't worry about it.

koraks said:

Thin silver images generally make good ambrotypes, which would indeed suggest underdevelopment, but transmission density on that second photo looks fine. If it scans & prints as desired, don't worry about it.

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Thanks! I’m not too worried. I actually rather like it! All this stuff is still just magic to me. I’ll be printing it this week. I’ll share results.

Love these!

koraks said:

Ah, great job! (And also on correctly spelling 'voilà; , haha!)

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I cringe every time I see someone online spell it “wah-la!” Ugh.