Pot Bromide 10%

Sal Santamaura said:

...Otherwise, only his print exposure times will increase...

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c6h6o3 said:

Yeah, but isn't that what he wants? I think his original complaint was that the times he had to use were too short to give adequate control.

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Indeed, but, as post #20 indicated, in my experience a much lower level of print exposure illumination is appropriate. If the negatives are somewhat thin but still off the toe, why change anything about their exposure and development? Simply using a low wattage bulb for printing seems more straightforward.

No one answered the first question properly. To get a 10% solution of KBr you mix, say 50 grams of KBr to 450 cc of water. Then you add water to 500 cc. If you mix 50 grams to 500cc of water you will not have a 10% solution.

Printing problems. RPippin, I wonder why you did not post this on the Azo Forum. I could have answered your questions, solved your problems, very quickly.

But you can trust what c6h6o3 writes. He makes the most beautiful prints.

Michael A. Smith

RPippin said:

How long is the shelf life?

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Richard,

KBr lasts forever. It will take years to go through 500ml of the stuff with Amidol. After 5 years, I've almost run through my 1st 500ml.

Michael A. Smith said:

No one answered the first question properly. To get a 10% solution of KBr you mix, say 50 grams of KBr to 450 cc of water. Then you add water to 500 cc. If you mix 50 grams to 500cc of water you will not have a 10%
Michael A. Smith

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That's what I said in the 3rd post in the thread

Ian

Ian, Sorry to quibble, but you said " . . . or 10g to 100ml water." That will not give you a 10% solution. If you add 10g to 90ml of water and then, after it is dissolved, add water to make 100ml, then you will have a 10% solution.

If you add 10g to 100ml of water the end result will be a solution that is more than 100ml and you will have a slightly less than 10% solution.

In practice, especially with only 10g, the actual percentage of the solution may not matter, but if we give advice here, we ought to be accurate.

Michael A. Smith

Would that not be short for what it said immediately before, i.e. you need to insert, mentally, "to water and make up" between "10g" and "to 100ml".

They don't use English like the rest of the world in the US yes the making up to 100ml was implicit

Ian

Ian Grant said:

They don't use English like the rest of the world in the US

Ian

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Not since Noah Webster, thank God.

Michael A. Smith said:

Ian, Sorry to quibble, but you said " . . . or 10g to 100ml water." That will not give you a 10% solution. If you add 10g to 90ml of water and then, after it is dissolved, add water to make 100ml, then you will have a 10% solution.

If you add 10g to 100ml of water the end result will be a solution that is more than 100ml and you will have a slightly less than 10% solution.

In practice, especially with only 10g, the actual percentage of the solution may not matter, but if we give advice here, we ought to be accurate.

Michael A. Smith

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Pretty sure I said something similar to what you just said. This is what I said:

"Any typical 10% solution in water is based off of the fact that 1ml water weighs 1g. So targeting a 1L 10% solution, ~900 ml water, 100g of whatever, add water to hit 1L if it isn't already."

Ian and Dayne may know the proper way to make a 10% solution, but their explication of it was not clear. At least it was not clear to me. Clarity of language in these things is important, at least it is to me.

Michael A. Smith

Sure, but considering the OP had no idea what a 10% solution even was, getting him 98% of the way there is better than 0.

I'm astonished that so many photographers prefer a non T-grain film. T-grain seems to me to be quite the superior technology.

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I can't speak for others, but personally I gave up TMY-2 because I couldn't develop it by inspection. Because of its magenta dye it looks totally black under the green light.
OK, I know I could use infrared goggles, but those are expensive, and uncomfortable to say the least.

My idea of a perfect film is one with the reciprocity behaviour and the characteristic curve of TMY-2, the base of TXP, and no magenta dye. But there isn't any.

If you really want to develop by inspection, why not develop to a reasonable time, process as normal, then bleach back fully and redevelop under room light?

Even then I can't see why this is absolutely necessary just to *use* a film. Do you develop all of your film by inspection? Why is that necessary?

It's not really necessary. It's just a developing method I happen to like. I find it very liberating, not having to make tests, to keep my eyes on the clock and thermometer, to mess with temperature control baths, to carefully measure the contrast each time I take a picture and decide beforehand how long to develop each sheet (a decision based on countless tests made in advance), and so on. I just expose for the shadows, put all negatives in the developer tray, then remove each sheet when it looks finished. It's freedom.
Indeed, it's not necessary. It's just a matter of convenience.
Besides, in the near future I'm going to move up to 8x10", for which I have no daylight developing gear at hand. So I'll have to develop it in trays, and tray development without inspection scares me.

I still use TMY-2 in small and medium formats, and probably always will. But in large format I just happen to prefer the convenience of DBI over the straight curve of TMY-2. In fact, in the upper part of the curve ABC Pyro seems to me to give good separation even with "normal" films, while a little overexposure - placing significant shadows in zone IV - takes care of the lower part of the curve. So overall I'm not so sure that the straight curve of TMY-2 is so important as it may seem at first glance. Its reciprocity behaviour is indeed great, but if I have to trade it for the convenience of DBI, so be it.

Anyway, my prints are not that great yet, and I still have much to learn and to practice before reaching a level where the subtle difference between the curve of TMY and that of other films will be visible in the print.

VladSoare said:

It's not really necessary. It's just a developing method I happen to like.

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I agree, and the inability to do DBI with TMY is the only thing about it I don't like. So, I use time and temperature. I suggest you do likewise. Kodak films are so well QC'd that your results will always be dependably repeatable.