Wet Collodion Failure

[Marc Leest]

Could it be the developer ? It seems that we used Ferric Sulphate (Fe2(SO4) 3) instead of Ferrous Sulphate FeSO4. The stuff we used was pale yellow instead of light green crystals.

tx, Marc

[scootermm]

marc... again... 15mins is a LONG time. Its called wet plate collodion, because the plate needs to stay "wet" (as in it needs to remain damp and moist).
I've done 8mins exposures where 3/4 of the plate is blank because it dried out.
Wet plate shooters use those HUGE brass lenses for more than just the swirly bokeh they give, they provide wide open apertures to make the exposure times manageable.
Before messing with everything else, this seems like the most obvious culprit. I'd try a wider aperture, more sunlight, etc to get some shorter exposure times.

[Marc Leest]

marc... again... 15mins is a LONG time. Its called wet plate collodion, because the plate needs to stay "wet" (as in it needs to remain damp and moist).
I've done 8mins exposures where 3/4 of the plate is blank because it dried out.
Wet plate shooters use those HUGE brass lenses for more than just the swirly bokeh they give, they provide wide open apertures to make the exposure times manageable.
Before messing with everything else, this seems like the most obvious culprit. I'd try a wider aperture, more sunlight, etc to get some shorter exposure times.

We will try of course shorter exposure times 1-2-3 secs as advised, we will do this when our class gathers next time. Just checking whether everything else might influence the process.
We use a Rodenstock 210 Gerogon on an vintage wooden process camera.
I 'll keep you informed.
thx, Marc

[smieglitz]

Here's an ambrotype showing evidence of drying out opposite the pour-off corner.



The plate was exposed roughly 2 minutes after it came out of the silver tank. Exposure was about 8 seconds in the camera in open shade IIRC. Developed in ferrous sulfate roughly 45 seconds after the camera exposure was made. So, from pouring through sensitizing, exposure and developing, the elapsed time was about 7 minutes total and the plate was still partially dried out. This one was made with sodium salts which tend to dry quicker than other salts such as potassium bromide and potassium iodide.

Joe

[smieglitz]

Could it be the developer ? It seems that we used Ferric Sulphate (Fe2(SO4) 3) instead of Ferrous Sulphate FeSO4. The stuff we used was pale yellow instead of light green crystals.

tx, Marc

Ferrous sulfate is the developer. It is light green in color in powdered form and tends to age to an orange sherry color when mixed with the water, acetic acid, and alcohol.

Joe

[Marc Leest]

So, we did a new test, and the results were much better, albeit not great. We got an faint image (exposure was 10 sec), but we had / have some problems with the sensitized collodion, while being in the silvernitrate bath, the collodion came loose from the plate, and it was not possible to continue (got an headache from the ether/alcohol vapours )

[billschwab]

..the collodion came loose from the plate, and it was not possible to continue

Are you cleaning your glass thouroughly? Roughing the edges of the glass? Subbing the edges with albumen? Using alcohol as a replacement for ether? There are many things that can contribute to lifting.