Aerial oxidation

[Dario]

Hi

Recently I had a sheet of 4x5 FP4+ come out under developed and apparently slightly fogged.

I tray develop and use semi-stand agitation.

If the film had not been fully immersed during development, that would explain the under development.

Could the fogging be aerial oxidation?

How long would film have to be exposed to the air before aerial oxidation becomes evident?

Thanks.

[Pere Casals]

Developer in bad shape (expired, spent, etc ) can cause fogging, this is named chemical fogging, if cause was light leaks then we have light fogging.

[Dario]

Thanks, Pere, but the developer is good. I've used the same stuff with no problems since getting the fogged neg.

[Pere Casals]

With some developers fog increase with rotary processing, if excessive speed, because of air mixed in...

You can check if this was a factor in your case, take an unexposed sheet, wet with your developer, and place half of it in a container with preserving gas (Tetenal Protectan, or gass with equivalent effect). After development time check densities and compare.