tell me how to clean trays

[Saganich]

Thoughts? I don't understand why this level of chemical intervention would be necessary. I'm scratching my head here.

 

[Beevo]

Please find an alternative cleaner.

Your post says to me that you do not have even the minimum knowledge/experience to use this cleaner (which is called chromic acid in the chemical lab) safely. You need really good ventilation and very serious personal protective equipment.

The recipe cited above says clearly that you need concentrated sulfuric acid. Concentrated sulfuric acid is 18M and is very corrosive and nasty stuff to work with. I would be surprised is you can find a company that will sell this to an individual.

Furthermore, chromate salts are both toxic and carcinogenic. They are also very bad for the environment both in their manufacture and, in not treated correctly, in their disposal.

The mixture of these two compounds is downright nasty stuff. I am a retired chemistry professor and do not consider many chemicals 'nasty'.

When I started out in chemistry in the 70s, chromic acid was commonly used the the lab. We had big vats of it that we would soak glassware in to clean it. By the turn of the 21st century chromic acid for routine glassware cleaning was completely phased out. (It is still used in rare instances where there is not a good substitute.)

If professional chemists don't use the stuff, I think that it is prudent that photographers stay away from it as well.

fgorga, I appreciate your reply and information. I have worked with acids, mostly in brass etching projects in my machine shop. Nothing approaching how nasty the recipe's level of corrosive however.

Your information about HOW concentrated the required acid is, did in fact have me abandon the project...

My mom had a big container of chromic acid in her lab, I remember it well along with the "don't mess with that" admonishments.

The points above are why I was asking prior to taking on the project. Any suggestions about a cleaner for bottles that actually would work? The Tank & Tray cleaner I have must be a weak solution of the TC-1

 

[Beevo]

Thoughts? I don't understand why this level of chemical intervention would be necessary. I'm scratching my head here.

I am trying to find a replacement for the darkroom Tank & Tray cleaner I bought decades ago that is no longer available. The stuff in the recipe is obviously hugely more powerful than the commercial bottle I have been using.

 

[Pieter12]

Trays get cleaned?

 

[Beevo]

Trays get cleaned?

The post mostly concerns cleaning bottles. The trays are fine as they are

 

[DeletedAcct1]

my trays are flat bottom , Cesco -lite, that have staining from all types of chems. all types of developers have been put through them, Amidol, PQ, MQ, and Glycin, etc. . .

I have also used these trays for toners, like selenium, gold, platinum, etc. for ALT. process.

I need to clean the stains from the bottom.

can you use a belach the stains out? Use like potassium dichromate, or chrome alum, or potassium ferricyanide? or do ijust use a house cleaner like ammonium?

what are the chems? at what percentage? and in what order " TO BOMB" these stains!!!!!?


thanks, greg

Potassium permanganate + sulfuric acid diluited, hot solution.
Rinse with metabisulfite after.
Rinse with water.
You'll have like-new trays and bottles.

 

[BobUK]

After returning to darkroom work after a few years break, household bleach was recommended to me to clean the dishes.
For a container I cut the top off a four gallon plastic jerry can to use as a bath to hold the bleach and trays vertically.
Left to soak for two days then rinsed off with fresh water. Worked fine for me.

Of course rubber gloves and eye protection are a must when splashing bleach around. I did have a sore throat for two days , so some sort of mask would have been a wise precaution for me.

Take care, whatever chemicals you settle on.

 

[jk0592]

Why not buy new trays, if the stained ones bother you so much ?

 

[DREW WILEY]

How do you intend to dispose of these nasty solutions once you are done with them? And you have to be very careful not to pour anything strongly alkaline like hydroxide down the drain after potassium permanganate, or you might blow up your plumbing. For amidol stains it's just a scrubber pad and elbow grease for me. Does the tray look brand new afterwards? No. But who cares in the dark?

And what are your lungs worth? - hopefully more than the expense of buying a new tray, if it comes to that.

 

[RalphLambrecht]

my trays are flat bottom , Cesco -lite, that have staining from all types of chems. all types of developers have been put through them, Amidol, PQ, MQ, and Glycin, etc. . .

I have also used these trays for toners, like selenium, gold, platinum, etc. for ALT. process.

I need to clean the stains from the bottom.

can you use a belach the stains out? Use like potassium dichromate, or chrome alum, or potassium ferricyanide? or do ijust use a house cleaner like ammonium?

what are the chems? at what percentage? and in what order " TO BOMB" these stains!!!!!?


thanks, greg

No need to clean; it's patina.

 

[BobUK]

Why not buy new trays, if the stained ones bother you so much ?

They are surprisingly expensive here. Always have been.
We are not all as rich as Charlie Clore