PE's concerns about non-photo-grade bulk chems

[bluechromis]

I use chemicals from places other than photo supply houses, including grocery stores and health food outlets, and have not noticed any problems.
In the article in the link below, the PE raises concerns about using non-photo-grade materials. This does not represent my own opinion, I am just passing it on if others are interested. Gainer, the ultimate scrounger, at one point mentioned concerns about grocery store borax because it might have an unknown mix of different forms of borax. His suggested solution involved putting the borax in water and then draining off the excess water. I didn't understand that.

On my computer, for some reason, the "Myths In Photography" document is hard to read, with html code showing.

https://www.photo.net/forums/topic/372857-collection-of-ron-mowrey-articles-myths-in-bw-photography/

 

[albada]

Thanks for posting this.
An interesting one is where adding marbles to a vitamin-C based developer to remove air killed the developer because the high iron-content in the cheap glass in the marbles caused iron ions to enter the dev, destroying it. And I use cheap marbles...

Mark

 

[Donald Qualls]

different forms of borax

Laundry borax might include different hydration levels -- but it's most likely decahydrate by the time it reaches the consumer, as that's (or so I understand) the atmosphere-stable form.

 

[nmp]

Laundry borax might include different hydration levels -- but it's most likely decahydrate by the time it reaches the consumer, as that's (or so I understand) the atmosphere-stable form.

Per MSDS, it is decahydrate.

https://cdn.commercev3.net/cdn.teachersource.com/downloads/MSDS/Borax-SDS.pdf

 

[Donald Qualls]

Per MSDS, it is decahydrate.

Okay. The box label on 20 Mule Team Borax doesn't give much information (though there is a link to the seller's web site for information and additional uses).

Washing (what the Gainer reference above is) is usually used to remove more soluble impurities from a less soluble desired product (at the cost of some loss of the desired species). For instance, if a synthesis produces, say, a yellowish impurity in your white target chemical, washing with a solvent that dissolves the impurity more readily than the "good stuff" will improve purity, but will lose some "good stuff" down the drain (or into the haz-waste stream). The larger the difference in solubility, the lower the losses.

Borax is fairly soluble in water, but given how most of it is produced (strip mining fossil dry lake beds, as I've understood it) it may still, after the manufacturer's purification to laundry grade, contain impurities of sodium carbonate, sodium bicarbonate, sodium chloride (and possibly other chloride salts), possibly phosphates of various types (I say that because those are mined the same way, though generally from different deposits) -- most of which are somewhat more soluble than borax. Most of us use borax in photography as an alkali that's not expected to directly take part in our intended reactions, however, and high purity isn't paramount in that application as long as certain impurities aren't present -- say, iron or copper salts if you're mixing Mytol (and those aren't likely to be much if any more soluble than borax anyway). A little boric acid does little or no harm (it'll lower pH a little, depending how much is present).

Unless Gainer wrote more to clarify what he was accomplishing with the water wash, I'd be inclined to believe it will do little to help, possibly nothing at all if you don't use water of high purity.

 

[bluechromis]

Link to thread with Gainer's borax comments:

https://www.photrio.com/forum/threads/borax-project.49055/page-2#post-712392

 

[Donald Qualls]

Aha! He was "purifying" by using a saturated solution, because of a belief that borax from ordinary sources may contain some pentahydrate (the "lumps") mixed with the decahydrate. Once in solution, the water of hydration is moot, and a saturated solution at a known temperature has a known strength. Well, he might be right; I'm pretty sure he was more of a chemist than I am.

I can only see this mattering if the borax is doing something other than setting pH (and possibly interacting with grain, as I've seen suggested). A couple percent too much borate ion in solution doesn't seem likely to have a huge effect, and would have none with a pH tested buffered solution (because you'd balance it out with your buffering agent).

 

[xkaes]

I used grocery / drug / hardware store chemicals for years without any problems, but I used them consistently, and I ran my own tests.

Since them, I've found that "photo grade" in bulk is pretty cheap -- enough for my budget. I have some reagent grade stuff -- but only because it was free, or thereabouts.

I must admit, I miss some of the fragances that were in some of the store-bought products -- especially Super Washing Soda.