Borax purity grade

gainer said:

I maintain that the use of a saturated solution and the temperature tables is the most accurate way to go for both borax content and insoluble solid content. It is certainly the simplest. I think the concern over supersaturation should be investigated, but otherwise it seems to be the best we ordinary people can do.

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What a pain - looking up tables and doing linear regressions and such. And just how accurately can you make volumetric measurements?

I find it so much simpler to just by grades that have known specifications and weighing it with my scale. Much more direct and much more precise and accurate.

Guys;

I have given a set of possible scenarios for the potential errors in using other than pure chemicals. This by no means eliminates them from potential use, but it does magnify the variables in processing and things you need to sort out if something goes wrong. I urge you to use chemicals of the highest purity for critical work. (Photo Grade)

As I said above, I know of several chemicals that Kodak uses that require ball milling before use, but are otherwise in commercial use in other areas and are otherwise photo grade except for the size of the solid matter in the chemicals themselves.

I refer you to my earlier posts on the possible uses in photography of some grades of chemicals available and I urge you to exercise caution with all chemicals. They can either burn or poison in their pure state and many retain that character even when dilute.

If you want any questions answered, please ask. The generic comments I've made can apply to all chemicals. You have my 30+ years experience in photographic chemistry here on-tap.

For Patrick:

Boranes as a family were used as additives to rocket and jet fuels. The energy released was just slightly below hydrogen and the boranes were liquid at room temperature. But, because they had only engineering tests they didn't know that from a chemistry standpoint the boranes were shock sensitive. Therefore, as the boranes aged and their sensitivity went up, airplanes began exploding spontaneously with the slightest bump. One of the last F10X series (maybe the F105) was originally designed to use either tetraborane or decaborane, as was the B58 (IIRC). In any event, without the boranes in use, the planes performance was way below spec and they were both quickly retired. This was quite a scandal in the late 50s when it became public. I'm surprised that you never heard of this. (This information comes from my Air Force magazines in the 50s, which is the official US Air Force publication for all officers.)

PE

Kirk Keyes said:

What a pain - looking up tables and doing linear regressions and such. And just how accurately can you make volumetric measurements?

I find it so much simpler to just by grades that have known specifications and weighing it with my scale. Much more direct and much more precise and accurate.

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You do not need to measure any volume of the saturated solution. You do not need to measure the weight of the borax. You add borax to water until some will not dissolve. You note the temperature. You find on the table the weight of borax decahydrate / 100 grams. You use that number with the required weight of borax to calculate how many grams of the saturated solution you need. You tare a plastic drinking cup and weigh that many grams into it. Nowhere in this procedure is a measure of volume required. 1/10 gram of error measuring this solution will produce, at 68 F, less than 1/200 gram error in the borax. The table presents values for every 5 C from 0 to 100 degrees and a simple linear interpolation is more accurate than most of us can measure weight. If you want, you can use Excell to plot a curve to hang on the darkroom wall. If you make and keep the solution at 20 or 25 C, there is no interpolation to be done.

If you can weigh to 1/200 gram and feel the need to do so, go ahead. But so far, you do not know, or at least have not told us, the specs of the borax you use, so you don't know any better than I do what is in the stuff you weigh to the milligram.

Come on, Kirk. I know you are smarter than this!

Kirk Keyes said:

PAt, you are completely wrong here. Your 20 Mule Team has no specification for insoluble matter. Therefore it cannot exceed the specifications that Mick's AR grade meets. And I would bet that Photograde has a specification for insoluble matter as well, and so it would not exceed that specification either.

If you're comparing specifications, you have to look at ALL of the specifications.

If you cannot see the logic of that, I pity you.

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The key word here is "bet", which I take to mean "I don't know for sure." When you find the specs of what you purchased as photo grade, let us know what they are.

How about all the other elements and compounds of them. Must I find an assay that determines them as well?

Saturating a borax (or any other compound) will increase the percentage of soluble impurities. We can decrease that percentage by adding twice or more the amount of borax required to form a saturated solution, thoroughly stirring, settling, decanting the clear liquor, which will contain not only saturated borax but a much larger concentration of impurities than the original borax. Now add water sufficient to form a new saturated borax solution from the "washed" borax. You can use the originally decanted liquor for less critival purposes such as laundry.

"This was quite a scandal in the late 50s when it became public. I'm surprised that you never heard of this. (This information comes from my Air Force magazines in the 50s, which is the official US Air Force publication for all officers.)"

Langley Air Force base was on the other side of the field, had no fighter command there AFIK, and almost all NACA flight research was done in the desert. I may have heard about it, but that was 50 years ago, and by that time I was into Simulation and Human Factors work. My best friend and co worker was Dr. Rayford T. Saucer (may he rest in peace), a clinical and experimental psychologist. In the meantime, I have had an attack of miningo-encephalitis which took away a lot of memory paths. I think the memories are still in there somewhere because they return a bit at a time. The human brain is a strange thing.

gainer said:

Saturating a borax (or any other compound) will increase the percentage of soluble impurities. We can decrease that percentage by adding twice or more the amount of borax required to form a saturated solution, thoroughly stirring, settling, decanting the clear liquor, which will contain not only saturated borax but a much larger concentration of impurities than the original borax. Now add water sufficient to form a new saturated borax solution from the "washed" borax. You can use the originally decanted liquor for less critival purposes such as laundry.

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This method can work, but will have the consequence of concentrating any solid impurities or concentrating any impurities less soluable than Sodium Borate. An example here might be Magnesium borate or Calcium borate which might increase in the solids due to their decreased solubility. Another possibility is the concentration of various Sulfates in the solids.

This would be an efficient method of removing Halides and Nitrates though.

It does increase the time you invest in purification and the water you use in mixing the solutions. You have to balance that against the expense of just buying a better grade.

PE

Photo Engineer said:

This method can work, but will have the consequence of concentrating any solid impurities or concentrating any impurities less soluable than Sodium Borate. An example here might be Magnesium borate or Calcium borate which might increase in the solids due to their decreased solubility. Another possibility is the concentration of various Sulfates in the solids.

This would be an efficient method of removing Halides and Nitrates though.

It does increase the time you invest in purification and the water you use in mixing the solutions. You have to balance that against the expense of just buying a better grade.

PE

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Still, I would expect most of the insoluble purities to remain in the undissolved sediment along with the excess borax. If, for example, I put 3x as much MC in water as needed to make a saturated solution (we can approximate here) and let it stand after initial agitation, the first liquid decanted should contain 2 or 3 times the soluble impurities and probably of the invisible part of the insoluble impurities. When I decant most of that and add distilled water to saturation, what I decant from that point contains more pure borax than the initial product. I am not going to evaporate to recover any dry solid. I can weigh out the required liquid. The liquid I decant could be evaporated to recover solid borax which should have less of both soluble and insoluble impurity, but this would not be necessary for most of our uses in developers. As I mentioned, a liter of D-76 at 20 C would require 42.5 grams of the saturated solution at 20 C.

BTW, the MC is stated by Dial Corp. to be non-abrasive, which would require that any silica or diamond particles be very small. It is also claimed to have no chlorine (which may leave soluble chlorides, I guess) and no phosphate.

Well, all I can comment on is that abrasive for skin is different from ability to penetrate a swollen gelatin matrix. These are two different issues as skin does not 'swell' in the sense that gelatin does. Gelatin is designed to be porous and skin is just the opposite.

PE

Photo Engineer said:

Well, all I can comment on is that abrasive for skin is different from ability to penetrate a swollen gelatin matrix. These are two different issues as skin does not 'swell' in the sense that gelatin does. Gelatin is designed to be porous and skin is just the opposite.

PE

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The statement I saw was with regard to scrubbing bright, shiny aluminum cookware with MC on a damp cloth. They sell other stuff for use on hands. I guess no chlorine, no phosphate and no abrasion are a selling point for people who clean aluminum pots and care what they look like.

gainer said:

IIRC, borax is pure as it comes out of the ground and is (or used to be) hauled away from Death Valley by wagons drawn by 20-mule teams.

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pic

The white stuff found in caves near the Potomac is more likely to be limestone, calcium carbonate. It's a little frightening to be in one of those caves and to notice that opposing walls match precisely. They are, for the most part, fault caves, and one wonders if the walls could not as easilly come back together.