Experiments with Metol and ascorbic acid.

Murray@uptowngallery said:

If a cheapskate is using alternate-sourced borax instead of 'photo grade' (or photo company supplied), for cost reasons, then there will be a limit to how much lab refining the cheapskate is able/willing to spend time/money on.

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Murray, I'm with you. But it is fun and interesting to discuss the various ways that we can devise to make our technical grade chemicals end up costing more than just buying the recommended grade in the first place.

gainer said:

The highest grade I have seen from Rio Tinto specs is NF, a pharmaceutical grade, which lists only heavy metals at <20 ppm.

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It's interesting that NF grade only is concerned with heavy metals (as quoted my Pat), and not any of the other substances that the other grades are spec'ed for, like chloride or insoluble matter. It really does point out the differences in the grading system for chemicals and how one should consider these things when chosing a particular grade for a particular use.

Kirk Keyes said:

It's interesting that NF grade only is concerned with heavy metals (as quoted my Pat), and not any of the other substances that the other grades are spec'ed for, like chloride or insoluble matter. It really does point out the differences in the grading system for chemicals and how one should consider these things when chosing a particular grade for a particular use.

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I don't know that heavy metal, expressed as lead, is the only impurity they are concerned with. It is the only one they listed. There is also a grade SQ for special quality that is granular and has very low allowable maximums of chloride, sulphate and iron. I imagine that the analysis for insoluble material is like the one you described a while back. If you can't see it in the solution and all the solution passes through the filter, whatever is insoluble must be negligible. I figure that if the Powdered Technical grade showed observable insoluble stuff, there would be a comment like < whatever the filter is specified to retain. The powdered and granular have the same specs in the soluble impurities.

I still don't know the ANSI Specifications for Photo Grade, but have applied for a copy. I don't expect to hear from them until after the holiday season.

I want to make sure everyone knows I am not expecting to produce chemically pure borax by my purification. It is a fractionation method, and since each fraction is less than 1, the final product cannot reach absolute purity until the amount left is 0.

I do not see, given the nature of borax, how a large amount could be stored in a bin so that any random sample would have the same hydration as any other. The manufacturer says that when humidity is lowered some of the borax that started as 10 mol will become 5 mol or even anhydrous. If the humidity becomes higher, the hydration moves back to 10 mol causing some clumping. It is not like NaOH which will form a puddle if left open to high humidity, so I suppose that if your borax were stored at high enough humidity it would all settle out at 10 mol and the percentage of borax decahydrate would simply be 100 - impurities. But if there is not enough humidity in the atmosphere to maintain the decahydrate, what you weigh to be 100 grams of borax decahydrate could be equal in sodium tetraborate content to more than 100 grams. If you purchase it as AR grade, and accuracy of measurement accuracy is critical to your purpose, then it would be well to make sure the the humidity in your storage container stays at the proper value. I don't know what that value is because most uses in developer are not very critical as to weight of borax, however critical they might be in ppm of impurities.

I got the ANSI specs for Photography chemicals sodium tetraborate, pentahydrate and decahydrate, 3 pages ata cost of about $21. In a nutshell, the summary of requirements is:

Assay, Pentahydrate or Decahydrate......101% min, 105% max.
Heavy metals (as Pb)......0.002% or 20 ppm.
Iron (Fe)......0.003% or 30 ppm.
Carbonate......To pass test.
Reaction to Ammoniacal Silver Nitrate.......to pass test.
Appearance of solution........to pass test.

The tests are described in great detail. Kirk or PE could perform them. Most of us have not the equipment nor the skills to perform them.

It appears that the specs would be met or exceeded by the NF grade described at www.borax.com, and the SQ grade would come very close.

You will notice that the minimum assay is greater than 100% and less than 105%.

Patrick;

I have read the spec and it is rather trivial both in content and in testing methodology.

The problem is that my time is more valuable to me than the cost in time and chemistry to run the tests. That is one reason why I prefer to buy the best to start with.

PE

Photo Engineer said:

Patrick;

I have read the spec and it is rather trivial both in content and in testing methodology.

The problem is that my time is more valuable to me than the cost in time and chemistry to run the tests. That is one reason why I prefer to buy the best to start with.

PE

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Could you at least take the time to define "trivial both in content and in testing"? I have a feeling that if you were to take the time you might find that 20 Mule Team Borax would pass the tests. There is no specific requirement for Chloride or Sulfate. I found it surprising that passing the carbonate test means that carbonate is less than about 1%.

The foreword states that "This is one of a series of standards that establishes criteria of purity for chemicals used in processing photographic materials."

I'm of the opinion that what you are really saying is "Don't confuse me with the facts. My mind's made up."

I'm not saying you should use any particular brand or grade of anything. The cheap stuff does pass the test for iron. Whether its content of chloride and sulfate would cause it to fail the ammoniacal silver test, I do not know. Perhaps you could inform us on the basis of known specs in what ways the best is better than the technical powder for processing film.

All right, I'll describe trivial in testing first.

Carbonate test, add sulfuric acid to a measured amount of borate solution and if it fizzes it fails the test but if it does not, it passes. That is my definition of a trivial and rather useless test, chemically.

Trivial in content now. Halides and heavy metals are critical in some applications and these are not addressed fully, just a few as seen from your post. As far as solids are concerned, a visual inspection is all they ask for. This is trivial both chemically and in content or intent for the purpose at hand, which is photography.

PE

Photo Engineer said:

All right, I'll describe trivial in testing first.

Carbonate test, add sulfuric acid to a measured amount of borate solution and if it fizzes it fails the test but if it does not, it passes. That is my definition of a trivial and rather useless test, chemically.

Trivial in content now. Halides and heavy metals are critical in some applications and these are not addressed fully, just a few as seen from your post. As far as solids are concerned, a visual inspection is all they ask for. This is trivial both chemically and in content or intent for the purpose at hand, which is photography.

PE

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Does that mean that you have in fact tested "the best" by those more stringent tests, or that you just don't trust the Photographic & Imaging Manufacturers Association, Inc. to know what is suffucient for film processing? You must have, at some time, tested 20 Mule Team Borax and "The Best" if you are so sure about the differences in purity.

I have run qualitative and quantitative analyses on many materials. I would say that these are qualitative in nature and are not indicative of much. Also, as you mention in the original post, these are ANSI. Are they PMA as you now state? PMA does not define standards AFAIK. ANSI and ISO define the standards that Kodak uses.

PE

I've been thinking of a different tack here. This is about Borax and developers but lets define Borax for all photographic uses.

It is used as a buffer in fixes as well as in developers. Now, we know that Potassium ion will 'poison' a fix. This is stated unequivocally in Mees, Mees and James and Haist. Therefore, for photographic use, a Borax buffer would have to include Potassium level as part of its specification.

Do you see my logic about looses specification and specifications intended for photo chemical use?

PE

The printout I got says at the top that it was approved 2/20/82 and reaffirmed 5/12/98. Secreteriat: Photographic & Imaging Manufacturers Association, Inc.

It is part of a series of chemicals used for processing photographic materials. None of the grades of borax that I have seen specs for have even mentioned Potassium, and I have seen a lot of them in the past few weeks, including pharmaceutical grade. Did you really get a guarantee of no Potassium? How would we know where to get the "best stuff"? I see your point about specifications. I have not seen how you know you have satisfied your needs. Do you know for a fact that your borax has been tested for Potassium?

The ANSI Standard claims only to imply a consensus of those substantially concerned with its scope and provisions. It further states "Although the ultimate criterion for suitability of a photographic grade chemical is its successful use in an appropriate photographic use test, the shorter, more economical tests described herein are generally adequate.

It would be a good thing if instead of saying that what would keep one from using the technical grade as specified by the manufacturers must necessarilly keep one from using it for any photographic purpose, to tell us what we more mundane uses we might put it to in the darkroom, especially since that grade has passed the use test over many years in many different developers.

Lots of typos. Not much sleep last night. Sorry.

gainer said:

The foreword states that "This is one of a series of standards that establishes criteria of purity for chemicals used in processing photographic materials."

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Pat - I broke down and got the specification yesterday as well. But I only had to pay $17 from ANSI online!

They are trivial tests! Nessler tubes in fact. (You have to work at a lab that has been in business for many decades to find a set of Nessler tubes. BTW, I just found a set of Nessler tubes in the lab last week!)

And I too was disappointed that ANSI was not more interested in the specific analytes we've been debating about for the last few weeks.

So I think the lesson to be learned here is found in the second paragraph, right after the line you quoted above:
"Although the ultimate criterion for suitability of a photographuc grade chemical is its successful use in an appropriate photographic use test, the shorter, more economical tests described herein are generally adequate."

What that tells me is that the ANSI spec is generally sufficient to descriminate between a grade that is useful in photography and a grade that is not sufficient for use in photography.

But, as PE points out, the real test is will the material work in the desired use. Buying a better grade than technical, like the NF (National Formulary) grade or especially the SQ which is very low in chloride, sulfate, and iron, guarantee that it would be suitable for all photographic purposes. (See http://www.borax.com/products1.html to find info on the grade Pat has been talking about.)

The only catch here is the SQ is a nuclear grade and is used for quenching runaway nuclear reactions. I but you would pay through the nose for that stuff. And no wonder it's so clean - you don't want to crap up your nuclear reactor with regular mule crap!

So did out those dusty, old Nessler tubes and get testing on your 20 Mule Team tech grade and show us that it does past the ANSI spec. I think it might pass all but the "reaction to ammoniacal silver nitrate" and maybe the "Appearance of solution" test. And that last one you can certainly do and let us know.

PS - if you need a set of Nessler tubes, here's some on eBay right now:
http://cgi.ebay.com/NIB-12ea-Nessler-tubes-50mL-LAB-GLASS_W0QQitemZ300156609242QQihZ020QQcategoryZ26407QQrdZ1QQssPageNameZWD1VQQcmdZViewItem?_trksid=p1638.m118 only $15 for 12 plus shipping.

We all know from watching the various CSI shows on the boob tube that identification of microscopic traces of anything is now a piece of cake.

A saturated solution of MC is clear as distilled water. I have no idea how much chloride-bromide it takes to fail the ammoniacal silver nitrate test. I am quite sure that a higher grade would be required for analytical work, but I'm also quite sure from my own long experience that for use in film and paper developers, MC is fine.
Now PE has thrown a new monkey wrench into the works. What if there is potassium in the MC and I want to use it to make fixer? First, I looked all through my copy of The Theory of the Photographic Process and could find no admonitions or even mention of the effects of potassium in fixer. Maybe there is a later edition than the third, but I think they would have known about it by then. But suppose we must avoid potassium in the fixer at all cost. How would it be removed from borax, especially if it is in the form of potassium tetraborate? Also, how much washing between developer and fixer would be required to prevent carryover from a potassium-containing developer, of which there are many? Perhaps PE was referring to color developer.

I must repeat my request that you guys also test what you buy to make sure you are getting what you think you got. I have used MC long enough to know it does what I expect of borax, but have you used it long enough to know that it does not do what you expect of it, or tested yours against MC to see if you could use it?

Mees, P 719, Mees and James, P 400 and Haist, Vol I, P 566 in which he states that fixers with Potassium salts are virtually useless. (Work of Frank and Schramm). Mees shows that K salts are roughly 4x slower as fixing agents.

So, I have found it in 3 places, besides having worked with Grant and others on some of this stuff.

Using Potassium Metaborate as a buffer in a fixer could paralyze its activity. A high percentage of potassium in Borate salts used to buffer a fixer might also slow it down or cause bad fixing.

A good stop or wash after a potassium containing developer will do a good job in preventing deterioration of the fix, but a standard test of the fixer will show either clearing time going up or silver halide being retained. Since we all check our fixer quality, this should not be a problem, right?

Patrick, you are questioning me on my home turf when you talk fixers! I learned from these people and many of the people that they refer to when I started at Kodak.

PE

"MC"? I'm missing the abbreviation.

"MC"? I'm missing the abbreviation.

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I think he means 20 Mule Team Borax. (He'd previously abbreviated this to "Mule crap.") IMHO, a poor choice of abbreviation, particularly for this thread, which began as one on metol/ascorbic acid (aka "MC") developers!

Kirk, you spelled out "mule crap" in your previous post. I just abbreviated that.

Potassium tetraborate is about 25 times more soluble in cold water than the sodium. By the difference in solubilities we could get a first solution that removed 95% of the soluble impurities in sodium tetraborate at a cost of about 5 grams of borax decahydrate. We pitch that, make another solution in cold water from the sediment removing 95% of remaining impurities and leaving about 90 grams. The soluble impurities are down to about 2 ppm. If that is not good enough, the process could be repeated using another 5 grams and leaving a fraction of a ppm.

I doubt you would have any difficulty getting Pharmaceutical grade from Rose Hill. IIRC, its about $2 a pound in 50 pound bags.

If you can filter instead of decanting, you could probably get 98% of impurities out at 1 pass.

srs5694 said:

I think he means 20 Mule Team Borax. (He'd previously abbreviated this to "Mule crap.") IMHO, a poor choice of abbreviation, particularly for this thread, which began as one on metol/ascorbic acid (aka "MC") developers!

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I got tired of repeating 20 Mule Team Borax some time ago, and since the original stuff was pulled out of Death Valley behind a bunch of mules, it seemed appropriate. I call my own batches MCB, so maybe it's a low grade of MC.

Patrick;

You neatly make 2 posts and sidestep my post. Interesting.

I am sorry you choose to ignore the post I made with the refereces you missed, but I am getting tired of arguing this back and forth. I am not against you, but am against passing on bad information.

What more do you want from me.

PE

I did not see this post before I wrote my previous one. I do not have a book by Mees with over 700 pages. There is no mention of the word "potassium" on p. 400 of Mees & James that I have. The only mention I found in regard to fixers was that a bit of potassium iodide in a fixer would speed up the wash time.

I probably would know more about these things if I made my own fixer, but I prefer to buy the best from those who do make it.

I am wondering more how potassium salts would be any more than trace amounts in borax and why they would not be given a minimum allowable number in the ANSI-PSA Standard. At any rate, it is 25 times more soluble than sodium tetraborate, and most potassium compounds are much more soluble than sodium tetraborate, so the method of fractional solution ought to minimize it quickly.

I should have said "maximum allowable".

Patrick;

The references I give are real. My Mees and James is the third edition and the paragraph is under "Thiosulfate Cation", but since you failed chemistry you may not know that Cation means positive ion including Cacium and Potassium.. Mees and James is not as good as Haist, which I helped edit.

I'm sorry, but I'm tired arguing this with someone who failed chemistry and now I see why. Please forgive me, but this is just exhausting to me. Neither I nor Kirk nor others can make you see your errors.

I'm not saying that potassium is present in large quantities in Borax. I'm saying that if it is it is a problem and should be in the ANSI standard or ISO standard for photograde Borax.

Your argument of chemistry with chemists, particulary photo chemists is misleading everyone, including yourself, and it is best you stop now.

I will not argue against your experience with NASA, but you insist on arguing against my experience and others in the field of chemistry which you admittedly failed. You cannot even find the reference in a textbook.

Forgive me, but this is true.

PE

Well, I was doing quite well in chemistry through inorganic, qualitative and quantitative analyses and chemical engineering lab. I have found that the only thing of real value that one learns in school after the basics, which I new before I went to school anyway, is how to learn more. I do know cations and cathodes and anions and anodes and a lot of other things. There is NO mention of potassium on that page under that heading or any other. Lithium, calcium, sodium and ammonia are discussed but not potassium. If you want to come look at my book, I'll get you a bottle of some really good local wine and we can go over it together. My copy was printed in 1969.

I reread the chapter on procesing after development beginning on p.397 and ending on p.407 in my 1969 edition. I found three references to potassium. The first was the one about adding some KI to the fixing bath speeding up washing.
The second was on p.401:
"Strauss found that sodium chloride acts as a fixing accelerator whereas sodium bromide has some retarding effect, although Sheppard & Mees found that 0.1 M potassium bromide had no effect on rate of fixation."
The third was on p 402:
"Where potassium alum is used as a gelatin-hardening agent in an acid hardening fixing bath, the retention of argentothiosulfate ions is greater."
I do not mean to imply that you are wrong, but that I had at my disposal no means of proving one way or the other. It is pretty obvious that my edition is not the same as yours.
I cannot imagine what borax would be used for in an acid hardening fixing bath. Boric acid I could see, but the culprit here was potassium alum, presumably in much greater quantities than any that might come in with impure sodium tetraborate.
It is also pretty obvious that my edition came out before the TMAX series.

My copy of Mees has over 1100 pages and is a standard book size (about 7x9 in) but very thick. Mees and James is a larger book in length and width, about 9x11 and thus has fewer pages.

In the Mees reference above and in Haist, they show plots of activity and potassium salts are 4x slower than sodium salts in fixation. Calcium also appears to slow rates.

Haist gives the actual reference to additional work, and there are published patents on how to overcome the deleterious effects of potassium ion on fix rate.

AFAIK, potassium salts have no significant effect on development, but do have an effect on emulsion precipitation.

PE