Dichromate bleach capacity?

[Fraunhofer]

It is in the title: what capacity does dichromate bleach in reversal processing have? Or can I use it as long as I am happy with bleach time?

My first batch has turned from bright orange to the color of bourbon, this I am wondering...

 

[Gerald C Koch]

Very simple the bleach should not be saved and reused. So the question of capacity is moot.

 

[pdeeh]

Very simple the bleach should not be saved and reused.

really?
I thought one of the advantages of a dichromate bleach was that it could be reused, unlike the permanganate bleaches which can really only be used one-shot.

 

[Erik L]

I have used years old sulphuric acid/dichromate bleach and it works as new.

 

[Gerald C Koch]

Each time you use the bleach it loses some of its capacity. Will this time be the one where it fails or is that one two uses away? Want to take a chance? Just how many pennies are you saving with reuse?

Then too there is the fact that the mixed bleach is dangerous if spilled. The mixed bleach reacts to form chromium trioxide a very powerful oxidizing agent. That's one of the reasons Ilford recommends the permanganate bleach.

 

[Photo Engineer]

I have used years old sulphuric acid/dichromate bleach and it works as new.

Was it used or not? This is the primary point here. If used it can go bad or be otherwise unusable, but the unused bleach can keep.

PE

 

[Erik L]

Was it used or not? This is the primary point here. If used it can go bad or be otherwise unusable, but the unused bleach can keep.

PE

Yes I missed the point of the op. I was speaking of a stock solution of bleach being useable not reusing it. I don't know the capacity of reusing bleach but surely wouldn't keep it after a session of processing.

 

[Fraunhofer]

I mix my bleach from scratch, so my question is really two questions:
A) how many sheets of 8x10 ortho film can I process say in 1 liter?
B) how long can I keep used bleach, assuming I haven't exhausted it?

Thanks

 

[Gerald C Koch]

Hard to answer question 1 as it depends on how much silver is to be bleached. Obviously the more silver present the more quickly the bleach is exhausted. Perhaps someone that used this particular film give an empirical answer.

As to storing the partially used bleach this is not a good idea.

 

[Gerald C Koch]

A bit of Chemistry 101. Perhaps a small experiment with oxidizing agents would be instructive. Place a small amount, say 1/2 tsp, of dry potassium permanganate on a plate. Arrange it into a small mound. Now wearing safely goggles place a single drop of glycerin on the mound. Within a second or so the glycerin will catch fire and burn vigorously almost explosively. This illustrates just how dangerous oxidizing agents like permanganate and dichromate can be.

 

[Fraunhofer]

A bit of Chemistry 101. Perhaps a small experiment with oxidizing agents would be instructive. Place a small amount, say 1/2 tsp, of dry potassium permanganate on a plate. Arrange it into a small mound. Now wearing safely goggles place a single drop of glycerin on the mound. Within a second or so the glycerin will catch fire and burn vigorously almost explosively. This illustrates just how dangerous oxidizing agents like permanganate and dichromate can be.

I've done that when I was much younger

My suspicion is that ortho lith film is putting a lot more silver into the bleach than regular film would, so I wonder if I'd notice the bleach being exhausted. I bleach by inspection in a tray, so is the only effect of the bleach being exhausted that I need more time or is there anything else I should be aware of?

 

[destroya]

not sure if it helps, but last time i did some B&W slides, with my 1 liter of dichro bleach I did 6 35mm rolls with it and they came out fine. I do use a half strength bleach and double the time