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# Article: Borax Project

1. ## 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.

2. Patrick, the 5% figure came from Kirk's post and suggested the limits of a 1% error in temperature either high or low. That is where it came from, nowhere else. In my experience the Borax from the Formulary is just fine.

As for all of this work, it seems to me that there are two considerations...

1. How much does this purification cost in terms of time and energy? Is it cost effective? It actually is not apparently cost effective as was described in an earlier thread I believe. I did not make the post nor have I tried to locate it or do the estimation myself. The very proposition of purifying my chemistry before I use it is alien to my thinking and work flow.

2. Should I even worry about borax? It is one of the chemicals that Kodak worked very hard to eliminate in the 60s and 70s and resulted in a whole new family of developers which used carbonate, TEA, or very low levels of borax to achieve superior results. The reason? Borax is toxic to some plants, some bacteria in sewage systems, some insects, and small children. Kodak wanted to become greener. So, I seldom use Borax.

PE

3. Originally Posted by gainer
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.
You may have made the ester that way.

But that's super effing hot - I wouldn't want to have to heat anything up that hot just to dissolve borax in something!

4. Borax is soluable at the rate of 1 kg / kg of water at 20 deg C according to my handbook. That is pretty darn high and should not need much heat at all to make a solution. I don't intend to try. See my last post. Or, consider what Kirk said. That is HOT.

PE

5. Originally Posted by Photo Engineer
Borax is soluable at the rate of 1 kg / kg of water at 20 deg C according to my handbook. That is pretty darn high and should not need much heat at all to make a solution. I don't intend to try. See my last post. Or, consider what Kirk said. That is HOT.

PE
Water to make tea should be nearly that hot. Are you sure of that number? The chart from www.borax.com says 4.71% at 20 C. We are at cross purposes here. I heated borax-water to get a saturated solution as it cooled. I heated borax-glycerol to make it dissolve faster and ran into a response that appeared to be a chemical reaction at around 250 F. Of course that is hot, but I think a roast coming out of the oven is that hot or hotter. A roast should be seared in a salted cast iron pan before being put in the oven. You want hot? Be a cook for a while.

6. Patrick;

Water boils at 212 F.

The Merck index lists borates and boric acid being quite soluable in glycerol. It states that 1 gram of Sodium Borate is soluable in 1 ml of water at 20 deg C. That is what I quoted above regarding borates in glycerine which is what you asked me.

A temperature of 250 F is above the BP of water at normal atmospheric pressure. A roast is nominally at 350 deg F coming out of the oven and will burn the pan unless you have kept liquid in the bottom of some sort. Grilling temperatures for meat are above 400 F. This too must be moistened somehow to prevent excess burning of the meat. The internal temperatures either way should reach 160 F or higher depending on the degree of doneness you wish. Most organic chemists love to cook.

I don't discount the formation of an ester, but it would have to take place at higher temperatures, I think, or would require a catalyst. What you observe is entirely in line with Kirk's explanation and not with the formation of an ester.

PE

7. Well, then, let me ask another question about glycerol. Is Metol soluble in glycerol? I would expect to find the Metol base to be soluble as it is in propylene glycol, but the H2SO4 is a problem. However, I find what appears to be solution of Metol in glycerol when temperature is raised to about 250 F, and remain dissolved as temperature returns to 20 C. I am guessing that a glycerol sulfate is formed that is soluble in excess glycerol.

BTW, when I am raising these temperatures, I do it a bit at a time. There appears to be a threshold above which solution occurs. I can dissolve 10 grams of Metol in 6 fl. oz. of nearly anhydrous medicinal grade glycerol and still have room for 10 grams of ascorbic acid.

8. Patrick;

Please re-read Kirk's post. Glycerol (Glycerine) acts like water in many respects.

PE

9. Originally Posted by gainer
I heated borax-glycerol to make it dissolve faster and ran into a response that appeared to be a chemical reaction at around 250 F. Of course that is hot, but I think a roast coming out of the oven is that hot or hotter. A roast should be seared in a salted cast iron pan before being put in the oven. You want hot? Be a cook for a while.
I guess you guys in West Virginia cook your roasts a little different how I prefer mine.

I'd hate to have to choke down a roast that was cooked to 250F - I think it would be overly well done, perhaps burnt. I prefer my roasts to be done to a nice medium-rare, about 135-140F. My chicken about 170F. If it gets to 190F, I find it's way to dry for me.

My oven is certainly going to be 250F (except for that medium-rare roast - I love slow cooking.) It will even be as high as 500F for some things, but I make every effort to avoid touching the oven. And I would avoid having to heat chemicals that hot too.

Not keep in mind that professionally, I've cooked stuff to well over that for doing certain chemical analyses. One in particular was when I used to do fuel testing. I had to do distillation ranges on gasoline and diesel. to do that, you put some in a boiling flask, attach a thermometer and a condenser, and distill 100 mls of fuel over into a graduated cylinder. You recorded the temp for the first drop over, the first 10%, the 50% volume, the last 10%, and the last drop over. I seem to remember that diesels would go up to about 600F for that last drop. Pretty damn hot.

But all that was done using lab equipment, in a fume hood, and with experience doing lab work. I do not recommend the home darkroom people really play with doing stuff like this at home. At least not without proper equipment.

10. I once worked with a guy that was cooking his turkey for Thanksgiving. He took it out of the oven, and the turkey shifted in the pan, causing him to spill the turkey juice/grease onto his feet. Even though the over was 350F or so, the boiling juice/grease in the bottom of the pan was probably not much more than 212F. Even at that temp, he ended up getting 2nd degree burns on his feet. Not a fun thing to do, especially on Thanksgiving.

It's stuff like that that dissuades me from heating stuff up that hot at home.

11. Originally Posted by gainer
I would expect to find the Metol base to be soluble as it is in propylene glycol, but the H2SO4 is a problem.
Why??

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