View Full Version : I need help figuring out fogging problems with wet plate

17-Feb-2018, 19:46
I started doing wet plates on my own today with all new stuff, so that means none of the system is known to be safe/working properly. I had HUGE fog at the start of the day, almost Dmax over the whole image. I chased it around and the majority of it seemed to be safelight fogging. By working in near-total darkness with only a small keychain red LED flashlight, the fogging was massively reduced with only a bit of fogging left, but I can't work out where that fogging is coming from. I've included a sadly blurred iphone pic of an unexposed plate. Here's all I can think of that might be useful to know:

1) UVP-X collodion, new bottle, just arrived
2) Freshly made silver nitrate solution
3) Developer is from Bostick and Sullivan, tried it both at the recommended 1:3 for 45 seconds and straight at 15 seconds
4) Fixed in TF-5 straight

a) Poured via waiter-tray method
b) left in silver bath for 3 minutes
c) back side blotted dry
d) developed in B&S developer for either 45 seconds at 1:3 or 15 seconds
e) rinsed in tap water
f) fixed in TF-5 for about 15 seconds (about 3x the clearing time)

So, with no exposure, I'm still getting this:

Due to the motion blur, it's hard to see but the whole plate is covered in light, whispy straw/tan colored haze in addition to the significant fogging that is visible on one edge.

Any ideas what it might be at this point?

Gary Beasley
17-Feb-2018, 19:56
That haze sounds like dichroic fog. Is something at the wrong ph? New fix or old? Contamination?

17-Feb-2018, 20:41
Did you prime your silver bath with a "sacrificial plate" overnight?
Don't hold yourself to those B&S development times. I have never developed a well exposed plate in the B&S developer (1:3) for more than 20-25 seconds. Development is done by inspection so if the image isn't coming up after 20 sec or so then your exposure is too short. If you have been holding out for 45 seconds, it is possible you are blowing out the plate. If the plate looks sandy or grainy then it is overdeveloped. How long are your exposures? natural light?

17-Feb-2018, 20:52
I have no way to check pH.

The fix is about 3 years old but the bottle of concentrate was just unsealed today and (obviously) is unused.

Yes, I iodized the silver bath by leaving the plate in it overnight.

I shot a single image outdoors in natural light and that was how I realized I had a fogging issue. Since then, testing has been in the darkroom only without any exposure to light at all. I did that to be able to eliminate all sources of fog related to both the plate holder and the camera but it means I couldn't see how/when the image was coming up in the developer (since there was no image).

With the level of fog in the final test, I think it'd be worth shooting a real image now to see when the image comes up in the developer to determine if development times should be reduced.

18-Feb-2018, 18:48
I continued to fight this today and didn't have any more luck through a couple dozen experiments.

Then I said the hell with it and tried a trophy plate sheet instead of glass. Absolutely perfect plate, no fog at all.

So something about the glass fogs the collodion.

18-Feb-2018, 20:25
What is the thickness of the glass you are using?

18-Feb-2018, 20:26
4 plates were 3.3mm thickness, the rest were all 2.2mm thickness.

18-Feb-2018, 21:18
How are you preparing/cleaning the glass?

18-Feb-2018, 21:19
cutting them from the sheet, grinding a flat on the edges with a waterstone, washing with blue dawn, then whiting.

18-Feb-2018, 21:40
cutting them from the sheet, grinding a flat on the edges with a waterstone, washing with blue dawn, then whiting.

And how are you cleaning off the whiting? Unless you are very thorough in removing all traces of it, you will get contamination of the plate and - eventually - your silver bath. Its best to do a hot water wash at the end to remove all traces of calcium carbonate, then cold water and rinse until the water doesn’t bead up on the glass. Dry with clean paper towel, then “breath test” to confirm there are no wiping marks left. I do a final polishing with a clean piece of cotton bed flannel.