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.
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!
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.
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
Sponsored Ad. (Subscribers to APUG
have the option to remove this ad.)
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.
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.
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.
Linear Mode
