Borax purity grade

[efreddi]

I'm running out of my stock of borax. I found the possibility to get some borax for household and/or wood preservation. Do you think that I may run in problem due to the purity grade? Any experience about it?

Thanks


Elia

[dancqu]

I'm running out of my stock of borax. Thanks Elia

I bought a pound from P. Formulary years ago and have
hardly touched it. Would depend upon how you plan to
use it. Mine is likely photo grade and would trust it
for any use. Borax from the store I'd trust to
make mildly alkaline a fixer. Dan

[jim appleyard]

I use 20 Mule Team borax from the grocery store to make D-76; never a problem.

[gainer]

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.

[Kirk Keyes]

As "pure" as anything that gets dug out of the ground. I'm not sure that your definition of "pure" as used here would meet most people's definition of pure.

I'd recommend getting some from the Formulary or another supplier of photo-grade chemicals.

[gainer]

Their's will probably come from the same grade that you buy at the supermarket. How many manufacturers of this product are there? Suppose you were a retailer like PF. How many different grades could you get if you tried? I haven't searched, but I have never have had a problem with 20 Mule Team Borax.

[Snapshot]

I would imagine that the 20 Mule Team borax is decahydrate in form and the photograde borax purchased from the formulary is pentahydrate.

[gainer]

AFIK the name borax is properly used only for the decahydrate. It is listed that way in the CRC Handbook of Chemistry and Physics, and was intended to be used that way in D-76. It is listed and defined that way in the 1941 edition of the War Department Technical Manual of Basic Photography. If you think you are getting the pentahydrate, and you are Adrian Monkishly obsessive, you should cut down the amount you use in order to account for the smaller amount of water of crystalization. This water has nothing to do with purity. In the usual uses of borax weight is not critical. Its solutions will have nearly the same pH over a wide range of concentrations. The capacity of a developer is more often limited by the accumulation of bromide than by depletion of borax. The tendency to single use makes the actual weight of borax even less critical. At worst, or maybe best, I believe, a change in concentration of borax will change the time constant of the reaction by which borax maintains its pH which may make a visible change in some edge effects.

[gainer]

20 Mule Team Borax is claimed to be made of 100% sodium tetraborate decahydrate. No other ingredients are listed. Do not use the penta or other hydrates thinking you are getting better purity. Whenever a recipe specifies borax, it means the decahydrate. Using the same weight of any other of its hydrates will cause you to have more than the specified amount of sodium tetraborate in your solution.

[efreddi]

Thanks to all for your answers!

Their's will probably come from the same grade that you buy at the supermarket. How many manufacturers of this product are there? Suppose you were a retailer like PF. How many different grades could you get if you tried?

That's the point! I suspect that the photografic grade is just the name and in reality the household borax is the same stuff. But of course the price and the availability is not the same.



Elia