1. 20 Team mule borax *is* borax.
2. 4gms per teaspoon will get you to where you need to go...

It is pure borax, or pure enough,... no need to convert.

Yes, but do not use Boraxo, which is a hand cleaner with other stuff in
it, including an abrasive.

feb504 from Lloyd Erlick,

'Pure' borax? Depends what that might be.

Borax is commercially available in three states of hydration. One can
buy anhydrous, pentahydrate and decahydrate.

The correct form to get is decahydrate. That is what is sold in
supermarkets (unfortunately not in Canadian supermarkets, though. The
stuff isn't seen here much.) Photographic formulas seldom stipulate
the hydration, but it is taken for granted to be the decahydrate. In
photo discussion, the word borax is understood to mean borax
decahydrate. No compensation for the weight of the water of hydration
should be necessary. It dissolves in room temperature or warm water
fairly easily and quickly (it's a laundry additive ...). Therefore,
the mules are pulling the righteous stuff. (I hate to think I'm
addicted to my darkroom because of Ward Bond, Sundays at my
grandmother's...).

The decahydrate is most often used commercially because it does not
absorb water from the air, does not cake, and if kept covered and
clean will not suffer in storage. It's also availble in huge
quantities at all times because it's used to do laundry, so it's
relatively cheap.

The pentahydrate form is fine, although a calculation and adjustment
might have to made on the weight, depending on how finicky one is. The
pentahydrate has the sad characteristic of absorbing water from the
air. It will eventually cake and solidify. I don't know how long this
process takes; if it's years, fine, if it's weeks, well, why hunt for
pentahydrate when deca is at the store? Penta is to be avoided unless
it can be used up quickly and is priced attactively.

Do not buy anhydrous borax. Not even if the price is attractive. Not
even if they pay you to take it. It will not dissolve in water during
your lifetime. You can add all the cosolubilizing agents you like. You
can dispose of it if you are mixing enough cement (it's way more
expensive than sand, though...). I have learned this the hard way and
no one else needs to follow my example. (If it screws up your cement,
don't talk to me about it.) Anhydrous borax might be considered 'pure'
borax, but it's not useful in the darkroom.

I don't know offhand what a teaspoon of decahydrated borax would
weigh. Most powders seem to be in the four or five grams per teaspoon
range. In most of the applications of borax in the darkroom,
especially fixers, the exact weight is not critical. Enough or more
than enough is the goal. Maybe for a developer it should be weighed
carefully, but even there I'm sure spoon equivalents will work fine.
I'd use four (maybe five...) grams per ordinary slightly round
teaspoon, and hope if there was error it would be toward slight
excess.

There is more at www.borax.com. Here's a quote:

---
Rio Tinto Borax operates California’s largest open pit mine in Boron,
California - one of the richest borate deposits on the planet. The
company supplies nearly half the world’s demand for refined borates,
minerals essential to life and modern living.

Borax traces its roots to California’s Death Valley, where borate
deposits were discovered in 1872. The twenty mule teams Borax used to
haul ore out of the remote desert...

regards,
--le
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