What is the necessity using Chemical Stop Baths?

[Xia_Ke]

I was doing all my own chemistry.
Made up to formula from the raw chemicals (cheap).
The Ilford manual didn't mention acid stop bath, and since the fixer I as using was acidic too, I saw no need for extra expense.
First a fill and immediate drain to wash off developer.
Then a 30-60 second soak to get some more developer out of the emulsion before moving on to fixing.

Now 35 years later some of the negatives show signs of incomplete fixing.
I think I carried on using fixer after it was exhausted, rather than mixing up fresh each time.
Several films haven't survived well.

Thanks Paul! I've thought a few times about mixing my own stuff. Chemistry was always one of my favorite subjects...LOL

Your post leads me to another question now What happens to film over time when it hasn't been fixed properly? Does it just fade?

[mtbbrian]

What happens to film over time when it hasn't been fixed properly? Does it just fade?

I don't know if fade is the correct term, I think it will show signs of discoloration, assuming it survives being exposed to light that long.
But you MIGHT, be able to fix and wash it again and it SHOULD be OK.
It's been a while since I have developed any film so I don't completely remember.
Brian

[photophorous]

I don't know if fade is the correct term, I think it will show signs of discoloration, assuming it survives being exposed to light that long.
But you MIGHT, be able to fix and wash it again and it SHOULD be OK.
It's been a while since I have developed any film so I don't completely remember.
Brian

If it's not fixed properly, it will be cloudy. In this case, you can refix it later. I don't know how much later you can go, but I've heard of people refixing after weeks or a month. Assuming it was in the fixer for at least a minute or two, exposure to light shouldn't be a problem...unless you try to develop it again.

The problem The Wombat was describing sounds more like incomplete washing. Fixer is acidic and if it's not properly washed out it will slowly cause the plastic film base to deteriorate and become discolored, which can not be reversed.

[SmartWombat]

I'll start a new thread on this.
Because I want to try to recover them.