strange white deposit in fixer tray

[Terence Falk]

i tray process my 4x5 and have been using photographers formulary T-5 fixer. i left the fixer in the tray for a few days and now theres this whitish rough deposit on the tray, very very difficult to remove. in all the decades of being in the darkroom i have never seen this. I can deal with the usual white fixer residue, but this is like sandpaper!

What gives? heres a shot of my tray and scratches into the film with my fingernail.

thanks

[Ulophot]

I am no chemist. Acid fixers can do significant damage, but TF-5 is near neutral. Decades ago, I went to prep a school darkroom that had been sitting vacant for several months since graduation. Someone had failed to clean up a large puddle of fixer from the shallow 316 stainless steel sink counter. The white deposit came off but the steel surface had been permanently eroded.

[koraks]

It's probably precipitated sulphur. If you allow a lot more to accumulate it'll look slightly yellow. Sulphur precipitated this way is indeed difficult to remove. Just scrub well.

[LabRat]

Smell it... Does it smell like rotten eggs??? Then it's sulfur...

And your fixer is bad...

Steve K

[jnantz]

is your tray metal or plastic ?

[xkaes]

That's normal. You can get precipitate in any tray that's been sitting for a while. Even the stock bottle of fixer will have some precipitate on the bottom. If you shake the bottle some flakes will come out and appear in the mixed fixer solution. It won't hurt the film or prints -- but you need to made sure it's washed off -- and it's one more reason to run a simple test every so often to make sure your fixer is still potent. You may need to increase you fixing time, reduce dilution, or buy/make new fixer.

[Terence Falk]

It doesn't smell at all- its like salt glued to the bottom. Someone from the Formulary got back to me and said it was most likely Calcium Carbonate. I did manage to get rid of it with a combination of a bathroom spray cleaner, very hot water and a lot of scrubbing. I have seen large crystals in fixer left out for a long time, but nothing like this.

[xkaes]

I have no idea how calcium carbonate would precipitate out of a fixer, but perhaps one of our resident chemists can jump in here.

Are you mixing your fixer with "heavy" tap water?

[jnantz]

It doesn't smell at all- its like salt glued to the bottom. Someone from the Formulary got back to me and said it was most likely Calcium Carbonate. I did manage to get rid of it with a combination of a bathroom spray cleaner, very hot water and a lot of scrubbing. I have seen large crystals in fixer left out for a long time, but nothing like this.

I was asking if it was a metal tray because some chemicals corrode metal and give that appearance, I know when I used SS D/D tanks there was sometimes corrosion.
Maybe your mystery chemical is carried over from your developer and when the liquid evaporated it was left.