Alkaline Stop Bath?

Snapshot · Sep 19, 2007

Hi All,

I understand the function of a stop bath is to halt the development of film or paper. Since developers are alkaline and require and alkaline pH environment to function, a neutral or acid stop bath is warranted in order to halt development. Or is it?

Is it possible to formulate an alkaline stop bath? I have heard of a couple of formulas that purport to be alkaline in pH. I'm interested, partly from a curiousity standpoint, in a feasible alkaline stop. An acid free workflow has an appeal for me, especially when I'm using my tanning developers.

Photo Engineer · Sep 19, 2007

Yes, an alkaline stop bath is possible.

That said, you should realize that an alkaline stop bath makes the removal of metol and similar compounds more difficult. Amino phenol compounds are not easily removed from coatings in alkaline solutions, and that is one reason to use an acid stop bath. Of course, hydroquinones are harder to remove in acidic solutions. Sulfite assists in their removal though by making sulfonate salts as the HQ oxidizes.

I ran into this problem head on once in the design of some processing solutions. It is not an easy problem to get around.

PE

Philippe-Georges · Sep 19, 2007

This is indeed interesting, particularly in combination with Poyro (-cat/-gal) developers for paper, and neutral fixers to.
I saw this : (there was a url link here which no longer exists) in the article section, but this one is still not neutral, and the smell...

Paul Howell · Sep 19, 2007

There are several commerical versions on the market as well as printed formulas. I have given some thought to using PF T4 for large format as it may help reduce the risk of pin holes in soft emlusions.

Michel Hardy-Vallée · Sep 19, 2007

There was another thread about this recently, and currently there is one product on the market that purports to be an alkaline stop bath:
http://www.monochromephotography.com/stopbath.htm

I have inquired about the product, and here's what I got:

"Hi, thanks for the mail. As far as I am aware Alkali-Stop is the only
alkaline stop available in the world. It works extremely quickly, stopping
films and paper almost instantaneously, and has a very long dish life,
although this depends on the number, size and amount of silver in the
prints, that you put through it. You can re-bottle it and use it for a
number of sessions. It starts to go yellow at the end of its life. I don't
have an MSDS sheet; not needed over here, but be assured that it is not
toxic; you can happily stick your fingers in this!
Photographers Formulary stock a lot of my products, but they don't yet do
Alkali-Stop...."

The thing that bugs me is the "MSDS not needed over here." This company is located in England, and I would think that such a country has provisions for declaring hazardous material. I have sent repeated requests, but to no avail.

Maybe he's just selling bottled water?

Xmas · Sep 19, 2007

mhv said:
Maybe he's just selling bottled water?

Maybe he is bottling faucet water... Bottled water is dear in UK

Noel

jim appleyard · Sep 19, 2007

Xmas said:
Maybe he is bottling faucet water...

Noel

Off topic, but for those who'd like to know, (I really can't imagine a lot of you!) Albany NY tap water is bottled as Aquafina; at least in the Albany area.

Michel Hardy-Vallée · Sep 19, 2007

jim appleyard said:
Off topic, but for those who'd like to know, (I really can't imagine a lot of you!) Albany NY tap water is bottled as Aquafina; at least in the Albany area.

Almost all bottled waters are tap waters, if you didn't know.

Philippe-Georges · Sep 20, 2007

Snapshot, I think we got a very 'clear' answer here...

Dave Miller · Sep 20, 2007

mhv said:
There was another thread about this recently, and currently there is one product on the market that purports to be an alkaline stop bath:
http://www.monochromephotography.com/stopbath.htm

I have inquired about the product, and here's what I got:

"Hi, thanks for the mail. As far as I am aware Alkali-Stop is the only
alkaline stop available in the world. It works extremely quickly, stopping
films and paper almost instantaneously, and has a very long dish life,
although this depends on the number, size and amount of silver in the
prints, that you put through it. You can re-bottle it and use it for a
number of sessions. It starts to go yellow at the end of its life. I don't
have an MSDS sheet; not needed over here, but be assured that it is not
toxic; you can happily stick your fingers in this!
Photographers Formulary stock a lot of my products, but they don't yet do
Alkali-Stop...."

The thing that bugs me is the "MSDS not needed over here." This company is located in England, and I would think that such a country has provisions for declaring hazardous material. I have sent repeated requests, but to no avail.

What's an MSDS, and what makes you think this product is hazardous?

Maybe he's just selling bottled water?

What's an "MSDS", and what makes you think this product is hazardous?

Akki14 · Sep 20, 2007

mhv said:
There was another thread about this recently, and currently there is one product on the market that purports to be an alkaline stop bath:
http://www.monochromephotography.com/stopbath.htm

I have inquired about the product, and here's what I got:

"Hi, thanks for the mail. As far as I am aware Alkali-Stop is the only
alkaline stop available in the world. It works extremely quickly, stopping
films and paper almost instantaneously, and has a very long dish life,
although this depends on the number, size and amount of silver in the
prints, that you put through it. You can re-bottle it and use it for a
number of sessions. It starts to go yellow at the end of its life. I don't
have an MSDS sheet; not needed over here, but be assured that it is not
toxic; you can happily stick your fingers in this!
Photographers Formulary stock a lot of my products, but they don't yet do
Alkali-Stop...."

The thing that bugs me is the "MSDS not needed over here." This company is located in England, and I would think that such a country has provisions for declaring hazardous material. I have sent repeated requests, but to no avail.

Maybe he's just selling bottled water?

The UK doesn't have MSDS - they have COSHH. See Silverprint's website: http://www.silverprint.co.uk/chem24.html

jim appleyard · Sep 20, 2007

Dave Miller said:
What's an "MSDS", and what makes you think this product is hazardous?

MSDS= Material Safety Data Sheet.

Dave Miller · Sep 20, 2007

jim appleyard said:
MSDS= Material Safety Data Sheet.

Thanks Jim, less of a mouthfull than our COSHH sheets, but seemly much the same thing.

Dave Miller · Sep 20, 2007

By the way the European COSHH stands for Control Of Substances Hazardous to Health. Just knew you were dying to know that; sorry bad pun intended.

Michel Hardy-Vallée · Sep 20, 2007

Dave Miller said:
What's an "MSDS", and what makes you think this product is hazardous?

As said above. Why would I assume that the product is not hazardous? And getting a safety sheet is also a good way to know what's in the bottle.

PHOTOTONE · Sep 20, 2007

I am wondering why someone would want an alkaline stop bath? Is it the smell? If odor is a concern, there are a number of buffered stop baths made that have a more pleasant odor. I don't see anything injurious to film and paper from using an acid based stop bath.

PHOTOTONE · Sep 20, 2007

If you are wanting to use an Alkaline fix, you could use standard acid stop bath, then put your film thru a quick water rinse before going into the fix, and that would wash away the acidic residue.

Snapshot · Sep 20, 2007

PHOTOTONE said:
I am wondering why someone would want an alkaline stop bath? Is it the smell? If odor is a concern, there are a number of buffered stop baths made that have a more pleasant odor. I don't see anything injurious to film and paper from using an acid based stop bath.

From a personal perspective, I was looking for an all alkaline workflow. I use tanning developers and I believe it would be of benefit from stain retention perspective.

Photo Engineer · Sep 20, 2007

Depending on the purpose of tanning, an acid/base cycle is useful to maintain the proper swell characteristics of gelatins tanned for dye transfer. As for tanning developers for stain purposes, the sulfite is probably more harmful than acid on the resultant image characteristics.

PE

Snapshot · Sep 20, 2007

Photo Engineer said:
Depending on the purpose of tanning, an acid/base cycle is useful to maintain the proper swell characteristics of gelatins tanned for dye transfer. As for tanning developers for stain purposes, the sulfite is probably more harmful than acid on the resultant image characteristics.
PE

If that is the case, then I should look at alkaline and low sulphite fixers for stain maximization. Would that be correct?

Photo Engineer · Sep 20, 2007

For best stain, the developer should be a pyro type developer with low sulfite, the stop should be a wash and the fixer should be plain fresh thiosulfate. This will maximize stain, but others have found excellent methods of achieving stain by other routes. You should query them.

I'm not a pyro developer user due to the inherent toxicity. Anchell and Troop call the pyro types of developers the most toxic that one can use. I agree with them.

PE

Snapshot · Sep 20, 2007

For the thiosulfate, I presume you would recommend ammonium thiosulfate instead of the sodium thiosulfate. Would that be correct or is plain hypo acceptable? I've heard that sodium thiosulfate doen't adequately fix modern emulsions due to their higher iodide content.

Photo Engineer · Sep 20, 2007

Sodium Thiosulfate will work just fine on B&W (NOT on color). You just have to get the right concentration and time. Sulfite can harm the image so the solution must be fresh.

PE

Snapshot · Sep 20, 2007

I appreciate your advice on the stop baths. Thank you.

Alkaline Stop Bath?

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