homebrew sodium metaborate?

heespharm · Mar 23, 2011

is this true?:

"From a Kodak Formulary publication, 1.4 grams of sodium tetraborate, decahydrate (Borax) + 0.3 gram of sodium hydroxide is equal to 2 grams of sodium metaborate (Kodalk) in a litre of solution"

I found this info here:
Dead Link Removed

john_s · Mar 23, 2011

Looks about right. There has been some ambiguity about the level of water of crystallization of sodium metaborate. This article has some clarification:

http://silvergrain.org/w/Metaborate

I would think that one might try to avoid excess of hydroxide because of its high pH. I think I would round down the hydroxide a tad.

heespharm · Mar 23, 2011

Looked at the link and found this:

In order to make 1.0g sodium metaborate tetrahydrate, mix 0.692g borax and 0.145g sodium hydroxide. When dissolved in water, these two make solutions of identical composition.1

Now how can 0.692 and 0.145 of 2 different ingredients (0.837g total) add to equal 1 gram... it's that against the law of conservation of matter? or am i missing something obvious

edit: ohhh the weight of water added

I guess this would be useful for solution b of pmk pyro?

Gerald C Koch · Mar 23, 2011

Sodium metaborate is so reasonable why would anyone want to make their own if they don't have too. Yes, there are people out there who have trouble obtaining chemicals. But for the rest it seems rather foolish as you have to use a dangerous chemical sodium hydroxide.

heespharm · Mar 23, 2011

True but I have borax and lye at home already

vanourek · Mar 23, 2011

Hello Heespharm,

I usually mix sodium metaborate as following: for 10 grams of metaborete I take 7,5 grams of borax and 1,5 grams of sodium hydroxide and put it in a glass beaker (or a clasic coffee - cup), mix it together and add about 2-4 drops of water (yes, really only so little) . Then I stir it with a stainless steel spoon, until it becomes an ugly sticky material, but I keep on stirring and the hydroxide starts to react with the water and borax (and heats up), until the water is evaporated and that sticky paste becomes crystallic again. Finally I have to crush it to a finer powder to ensure good and fast dissolving in water (or the TF-2 fixer, where I use the sodium metaborate).

Sorry for my english

Keith Tapscott. · Mar 23, 2011

heespharm said:
is this true?:

"From a Kodak Formulary publication, 1.4 grams of sodium tetraborate, decahydrate (Borax) + 0.3 gram of sodium hydroxide is equal to 2 grams of sodium metaborate (Kodalk) in a litre of solution"

I found this info here:
Dead Link Removed

That's exactly what it says in my Kodak formulary.

heespharm · Mar 23, 2011

vanourek said:
Hello Heespharm,

I usually mix sodium metaborate as following: for 10 grams of metaborete I take 7,5 grams of borax and 1,5 grams of sodium hydroxide and put it in a glass beaker (or a clasic coffee - cup), mix it together and add about 2-4 drops of water (yes, really only so little) . Then I stir it with a stainless steel spoon, until it becomes an ugly sticky material, but I keep on stirring and the hydroxide starts to react with the water and borax (and heats up), until the water is evaporated and that sticky paste becomes crystallic again. Finally I have to crush it to a finer powder to ensure good and fast dissolving in water (or the TF-2 fixer, where I use the sodium metaborate).

Sorry for my english

Thats brilliant... Thanks for the detailed directions

homebrew sodium metaborate?

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