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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

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    Quote Originally Posted by Murray Kelly View Post
    188g seems a lot of borax. Does it need all that to just buffer it? Or is it a matter of 'those damned dots'?
    Murray
    Yep, it's the dot. The number is 18.8 grams, The saturated solution at 20 C is 4.71%, or 4.71 g/100 ml. I think my city water in Newport News, VA had more stuff in it than this developer.
    Gadget Gainer

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    This stuff is even more dilute than the older formula (0.25/9g/25g - IIRC) which I thought worked so well. Not quite as dilute as PC-glycol altho that has a higher pH.
    Soon we'll be taking chems out of the water! :-)
    Murray

    Quote Originally Posted by gainer View Post
    I think my city water in Newport News, VA had more stuff in it than this developer.

  4. #33
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    Finally I have a real question. Given what you have said, what would the difference in the pH be of (say) your P-C-Borax developer above using an unlikely but possible scenario that one had a box of pentahydrate versus a box of pure decahydrate and made the developer from one or the other?
    Approximately 20g /litre would show a difference of how much pH?
    My suspicion is that the single decimal place pH meter wouldn't help one distinguish the one from the other. Yes/no?
    Murray

    Quote Originally Posted by gainer View Post
    My Borax Project
    SNIP)
    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.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
    SNIP

  5. #34
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    Quote Originally Posted by Murray Kelly View Post
    Finally I have a real question. Given what you have said, what would the difference in the pH be of (say) your P-C-Borax developer above using an unlikely but possible scenario that one had a box of pentahydrate versus a box of pure decahydrate and made the developer from one or the other?
    Approximately 20g /litre would show a difference of how much pH?
    My suspicion is that the single decimal place pH meter wouldn't help one distinguish the one from the other. Yes/no?
    Murray
    It takes a fair amount of change in amount of borax to make a change in pH of a solution of borax. However, the concentration of borax has a greater effect on local dynamic changes in pH than will be seen after equilibrium is reached. Frankly, I am not one to quibble, as PE will testify. However, the difference in number of molecules between 2 grams each of penta- and decahydrate is about 30%, so if you had all penta and thought it was decahydrate, you would be getting the equivalent of 2.62 grams of the specified decahydrate. Would that make a visible difference in the output of D-76? It depends on how sensitive you are to such things. I take it that the purification process would be worth while if one could not buy the Photo grade stuff, of PE and Kirk Keyes would not chastise me for trying to put Photo Formulary out of business by doing it.
    Gadget Gainer

  6. #35
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    We like to catalog and categorize things to make general rules about how to change things. We have solvent developers, non-solvent developers, high acutance developers, and on and on. With a good lens sharply focussed on the subject of interest, why should we not be satisfied with what we saw on the ground glass or in the viewfinder? How would you categorize a sulfiteless solution of Phenidone, ascorbic acid and borax in water? I did it to see what would happen. Where's the preservative? How can I have fine grain without a silver halide solvent? Thus far, I have tested only HP5+ and Arista EDU 400, and I have 11x14 prints that show no grain from greater than 6" viewing distance.

    Of course, ascorbic acid is an antioxidant. At the pH of borax, one could wait all day and not see any sign of development, but add a pinch of Phenidone and Voila! Is it synergism, or simply rapid regeneration of Phenidone by the ascorbate, or are both the same? Is the ascorbate also a solvent of silver halides? I have read that it is a surface developer which fact makes its grain finer, but it wasn't even a developer until I added the Phenidone. But who cares about all this if it works?

    Forgive the ramble.
    Gadget Gainer

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    I was all set to process my 2kg of borax as you describe (except I was planning to return the supernatant to the boiler each time for the next 500g so's not to lose the 47g/l) when I went to Google and found the MSDS for both brands that I have here. They are both described as tetrahydrate 99/100% depending on the brand.
    I put away the kettle and borax.
    My final move would've been to cool the last supernatant in the photo fridge to get almost all the borax back.
    Selling tetrahydrate makes sense commercially - why give the customer the more concentrated pentahydrate if one can sell some water with it?
    The P-C-Borax does indeed work well. I especially liked it with Copex rapid as a stand developer. I just don't know how long it lasts, made up. I used it as a one-shot. Borax is much more soluble in glycerine and ethylene glycol - maybe it's possible to make a concentrate?
    Murray

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    The problem is not always in what you bought, but in how long and under what humidity conditions it has been kept. When you open the container, if the humidity is low, some of the decahydrate is likely to become pentahydrate. Over the course of time, although the borax can still be considered to be the same purity as when you got it, the water content may not be. Or, it may be. If it's in a saturated solution, you know the equivalent weight % of the decahydrate by the temperature of the solution, but there's a lag. But if you make a saturated solution at a given temperature, let it stabilize, and decant some of the liquid, that part will have that same concentration at any higher temperature. It's really a simple thing to do and is common lab practice where accuracy is important. If your borax is pure enough, there is no need to do the purification steps, but it's still a good idea to keep the saturated solution. It is much simpler to measure out a certain liquid volume to the nearest ml than to weigh out to the nearest 0.1 g. Besides, if you really think 0.1 gram precision is required, you may not get it with a solid that has two possible states of hydration.
    Gadget Gainer

  9. #38
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    Quote Originally Posted by Murray Kelly View Post
    I was all set to process my 2kg of borax as you describe (except I was planning to return the supernatant to the boiler each time for the next 500g so's not to lose the 47g/l) when I went to Google and found the MSDS for both brands that I have here. Murray
    BTW, Murray, what did you expect to gain by putting the supernatant liquid back in the pot? That contains all the garbage that was leached out of the good stuff. Reminds me of my daughter's idea for saving gasoline. She thought of putting a windmill atop her car driving a generator which would drive an electric motor to assist the gasoline engine.
    Gadget Gainer

  10. #39
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    Not only was I going to ensure there was tetrahydrate (not necessarily for long, you tell me) but since the stuff is so pure it was my intention to allow any small amt. of impurity build up in the supernatant as a solution without tossing 47g/l every time. Just being frugal.
    My daughter noticed the temperature gauge shoot up and sped home in case it blew up!

    Murray

    Quote Originally Posted by gainer View Post
    BTW, Murray, what did you expect to gain by putting the supernatant liquid back in the pot? That contains all the garbage that was leached out of the good stuff. Reminds me of my daughter's idea for saving gasoline. She thought of putting a windmill atop her car driving a generator which would drive an electric motor to assist the gasoline engine.

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    SPF-3 VS RODINAL 1+25

    Murray, I'm not upset with you for tinkering with my illustrations. I'm posting the comparison that really counts, the one between SPF-3 and Rodinal 1+25. All I have to do now is find where I saved them.

    They are "hybrid" photos, using a flat bed scanner at 600 dpi to read 11x14 analog prints. If you print them to 8x10, you should view them from about 6 ft to get proper perspective.
    Attached Thumbnails Attached Thumbnails RODINAL 25 HI RES.jpg   SPF-3 HI-RES.jpg  
    Gadget Gainer

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