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Article: Borax Project

  1. #1
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    Borax Project

    My Borax Project
    Borax is useful in many ways. Some of us worry about the purity of the commonly and cheaply available 20 Mule Team Borax. There is another concern in cases where accuracy of weight is important. Borax has 2 possible states of hydration, decahydrate and pentahydrate. If a 100 gram sample of pure borax has pentahydrate and decahydrate mixed, the assay will show a greater weight than 100 grams. If 5 grams of a 100 gram sample are the pentahydrate and the rest the decahydrate, no matter how purely the saple is composed only of sodium tetraborate and water of hydration, the assay will show 101.5 grams of the decahydrate. There is no way you can tell at time of collecting a sample from a large batch of pure mixture how much of each hydrate you are getting.
    A common solution to both problems is literally a solution. A saturated solution of borax at a given temperature contains a known weight of borax expressed as the decahydrate, whether the solid used to make the solution was penta- or decahydrate. If the solution was made saturated and separated from the solid at a low temperature, it will have a constant weight of borax per unit weight of solution at any (reasonable) higher temperature. The weight per unit volume will stay constant enough for most uses.
    A simple way to purify a large quantity of borax at the expense of a smaller amount is to make a concentrated solution in boiling water, allow it to crystallize at a temperature below that desirable for keeping, and decant the clear liquid and discard it or use it for cleaning. The soluble impurities in the original borax are presumed to be uniformly distributed in the liquid, so that if, say, 90% of the liquid is removable by decantation and/or fitering, the remaining impurities will be reduced by 90%.
    656 grams of borax decahydrate are soluble in a liter of solution at 100 C. If the temperature is reduced to, say, 15 C, there will remain only 37.9 gram in the discarded solution. The remaining 618 grams of borax has been cleansed of about 90% of its original soluble impurities and is sufficient to make 16 liters of borax solution.
    When I first proposed this approach it was considered by certain of our resident chemists to be a complicated alternative to paying the money for analytical reagent grade of borax and weighing it to the milligram, even though it is well known among other chemists and for the same reason I stated above that such a degree of precision is not warranted by the uncertainty of the state of hydration of borax. Then, to top it off, I had a senior moment and recommended the use of 10 times more of my borax solution than was proper for D-76. That was seen as proof that I knew not whereof I spoke. Furthermore I made the assertion that 10 times too much borax was not as bad as it might seem. In the process of defending my assertion, I found a variation of D-76 that I may (or may not) call "serendipitol". Serendipity is exemplified by the fellow who accidentally walked barefoot through a certain kind of animal excrement and discovered it to be an excellent cure of athlete's foot. I seem to remember that the animal was of the male bovine type.
    I made 3 liters of D-76, two with 10 times the prescribed amount of borax in the form of 425 ml of a 4.71% solution. To one of these were added 20 grams of boric acid crystals. The third liter was made as old-fashioned D-76, using 42.5 ml of the 4.71% borax solution. The rule of this game was to pretend I didn't know about the extra borax and treat it the same as store-bought. I shot 36 exposures of HP5+, bracketing plus and minus 1/2 stop. Any consecutive 4 frames had all three exposures. As it turned out, the nominal exposure was quite good in all three cases.
    I have three cases to show. Each one shows a low resolution scan of an 8x10 print to show its chiaroscuro and a high resolution scan of a portion of that print to show resolution and granularity. The one labeled "D-76" is Metol, 2 grams, hydroquinone,5 grams, 42.5 ml of 4.7 % purified borax solution, and demineralized water to make 1 liter. "D-76 B+" is Gadget's mistake with 425 ml of the borax solution. As cure of the resulting high contrast, I took a cue from more recent D-76 and added 20 grams of boric acid crystals per liter of the mistake and called it "D-76 BB". I used VC paper. I had the contrast turned all the way down for the D-76 B+ negative and no filtration for the other two. I set printing exposure for each print to make the whitest part of the fuzzy stuff in front of my great granddaughter's teddy bear the same.
    I got the expected high contrast from Gadget's Mistake, but grain and resolution were not seriously affected. Adding boric acid to make D-76 BB brought contrast back to near normal.
    Would there be a technical reason for making D-76 BB? Its pH is lower initially than that of traditional D-76 but its activity is nearly the same, at least on short strips. Its buffering capacity should be greater, both locally and overall, which should make a difference in the effect that different types of agitation make on gradations, but the effect may not be what one is looking for. In any case, it is another possible pictorial control.
    Gadget Gainer

  2. #61
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    Quote Originally Posted by Kirk Keyes View Post
    To set the record straight, I suggested that 20 Mule Team may contain impurities that would interfere with photgraphic uses, and that photo-grade borax gives one some assurance that your reagents are suitable for photographic uses.
    I have refrained from posting in this thread until now. I feel that I have to clarify my position as well.

    Kirk not only has his chemistry straight, he has also stated in this quoted post my own thoughts on this matter.

    The most common impurities are halide salts and insoluable colloidal salts. Patrick has alluded to the latter in the past saying that some of his Borax solutions are cloudy and the cloudy suspension cannot be filtered out.

    This whole thing may be summarized by saying that Patrick is trying to prove his point, that he can compound usable developers. That is conceded, but due to lack of full checks, we don't know how they compare in detail to off the shelf developers. In fact, in some test comparisons shown in other threads, I (and others) have given the tip of the hat to the commercial (albeit modified) developer.

    I am not a borax chemist, but in private notes, I have exchanged similar, but less specific informaiton with Patrick discoraging him from the view that an ester or other type of compound is being formed. This was obvious to me, but the details were unclear and I had no text references for help. I thank Kirk for giving us the complete story on this.

    PE

  3. #62
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    interesting! up until a couple of months ago when another member very generously gave me about twenty pounds of old photo chems, I had always used 20 Mule Team Borax from the grocery store in my home brew ....

    That stash of chemistry included a one pound jar of Kodak Borax - which I have been using ever since.

    I too noticed the cloudiness with the grocery store Borax...and now that it is mentioned, I have not noticed it with the Kodak Borax.


    Very interesting. I think I'll leave the 20 Mule team in the laundry room from now on.
    Last edited by BradS; 07-09-2009 at 06:09 PM. Click to view previous post history. Reason: re-arrange things a little bit for readability.

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    I'm no "borax chemist" myself, but as an analytical chemist, you can be exposed to a lot of different analytical techniques that are sometimes forgotten in the modern world of chemistry. Nowadays, to measure boron content, an ICP (Inductively Coupled Plasma atomic absorbtion spectrophotometer) or even an ICP-MS (one with a mass selective spectrometer attached) would be used. 50 to 20 years ago, an AA (atomic absorption spectrophotometer) would have been used. The titration with glycerine was used from about 100 years ago until labs could afford AA's in the 50s and 60s.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  5. #64
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    In point of fact, the borax that I used in these later experimental developers was the photo grade from Photographers' Formulary. My main interest at this time has shifted from borax to glycerol. I had been using it as a solvent at time when I had no propylene glycol at hand. At room temperature, it seems to serve as well except for the higher viscosity for the preparation of higly concentrated stocks like PC-Glycol. It occurred to me that the high solubility of borax in gylcerol would allow a single solution concentrate of Phenidone, ascorbic acid and borax in glycerol. I am pretty sure that in the process of heating the mixture for faster solution to between 250 and 300 F I did form the glycerol borate. The pH of the working solution was considerably lower than I would have gotten from a water only solution of the same small amounts of Phenidone, ascorbic acid and borax.

    The 1+25 working solution of the glycerol stock seems to have buffering properties, as the addition of fairly large amounts of borax produces little change of pH, which stays below that of a 0.1N borax solution. The resulting developer is quite good, but slow.

    There is also a glycerol sulfate, which gave me the idea test the solubility of Metol in glycerol. I have dissolved, with heating, 10 grams each of Metol and ascorbic acid in 180 ml of drugstore glycerol, which is nearly anhydrous and of medicinal quality.
    Last edited by gainer; 07-09-2009 at 10:34 PM. Click to view previous post history. Reason: misspelled glycerol
    Gadget Gainer

  6. #65
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    Quote Originally Posted by Photo Engineer View Post
    I have refrained from posting in this thread until now. I feel that I have to clarify my position as well.

    Kirk not only has his chemistry straight, he has also stated in this quoted post my own thoughts on this matter.

    The most common impurities are halide salts and insoluable colloidal salts. Patrick has alluded to the latter in the past saying that some of his Borax solutions are cloudy and the cloudy suspension cannot be filtered out.


    PE
    The very first thing I did was to prepare a nearly saturated solution of borax in very hot water. After cooling, most of the borax had settled out, leaving only about 47 grams/liter in solution along with most of the soluble and colloidally suspended impurities. Decanting the solution thus removed most of the soluble impurities. There is no point in trying to filter out any impurities, be they truly dissolved or colloidally suspended, if they can be decanted at the cost of only a few percent of the original amount of borax. Furthermore, even the best grade of borax is likely to be a mixture of pentahydrate and decahydrate, so in any case where an accurate assay of Na2B4O7 is required, the standard procedure is to prepare a saturated solution. This solution, if kept at a temperature above that of its formation, will have a known borax content expressed as weight percent of the decahydrate. Thus, a saturated solution formed at 20 C will contain 4.71% sodium tetraborate decahydrate, or 47.1 grams per liter.

    I think you will see if you look at my developers, that I have for many years spent most of my effort designing sulfite-free developers. The major thing I have against sulfite is cost and local avilability. It is often the most expensive component, and among the hardest to get. Anyway, it's part of my fun to see what I can do with what I can get in the middle of Wild and Wonderful West Virginia.
    Gadget Gainer

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    Quote Originally Posted by gainer View Post
    The major thing I have against sulfite is cost and local avilability. It is often the most expensive component, and among the hardest to get.
    It's easy to get it at a photo store. At least the photo shops around here.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

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    Quote Originally Posted by gainer View Post
    Thus, a saturated solution formed at 20 C will contain 4.71% sodium tetraborate decahydrate, or 47.1 grams per liter.
    Pat - do you make corrections for when your borax solution is not at exactly 20C?

    I hope you have an accurate and precise thermometer. If you are off by 1 degree, you will get a 4.52% solution if you are low, and 4.94% if you are high. That's an error of 5% for just a change of 1 degree Celcius.

    I have to say I think just wieghing your borax is a lot simpler and more expedient. And more accurate.

    And that's assuming you have time to let your borax solution sit around so that it's truely saturated - not undersaturated and not over saturated.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  9. #68
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    Kirk, if the saturated solution has been decanted from the undissolved sediment at 20 C, it will contain 47.1 grams of borax per kilogram of solution at any higher temperature. For practical purposes, even if you measure by volume at a higher temperature, the change due to expansion of the liquid will not throw you off as much as the possible variation in weight per mol of Na2B4O7 due uncertainty of the average amount of water of crystallization. How do you ascertain that number? Every time you open the container, the contents are subjected to possible changes in humidity. The 5 pounds I bought from the Formulary has huge lumps, small lumps and powder, which indicates changes in water of crystallization have occurred, but from what to what?

    If you are going to be a stickler for precise measurement of borax, your best bet is a saturated solution. I think the best way to make it is to start from saturation at a higher temperature and to let it cool to the desired temperature. If it takes a while, so be it. as the saying goes, "Think ahead."

    I did not continue my formal study of chemical engineering, but changed to aeronautical. I am an engineer by nature, as anyone who knew me during my years at NACA-NASA would testify. As one of our instructors in engineering was fond of saying, "Engineers can do anything."
    Gadget Gainer

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    I think that phrase should be "Engineers will do anything". This does not give it the stamp of approval however, nor does it ensure that their chemistry is correct as Kirk has pointed out.

    Imagine building the port on a Mercury capsule (an example given by Patrick in another thread), and it has a 5% variation in size. One would leak (too small), one would crack (too big), and one would be just right! I think that this analogy is apt although the results would be far less draconian in photography. If you had a 5% variation in alkali content, your pictures might be usable but you might wonder why your contrast or sharpness varied as much as it did.

    PE

  11. #70
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    And what makes you think I might have had a 5% variation in alkali content? I told you I used the photo grade borax I got from PF. Is it that bad? Even the stuff I get by processing the household variety is better than 5%.

    By the time the Mercury became a project, I had been assigned to do basic human factors research, and to design star charts to be used as backup reentry alignment. What did my education in AE have to do with that? It made me ask questions and search for answers. I no longer have the technical library I could access at Langley Research Center.

    Kirk, there is no photo shop within 100 miles of here in any direction. My formulas are not only for my use, but have been used in remote locations in New Zealand. (Jacko Twist, where are you?)
    Gadget Gainer



 

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