Sodium metaborate question

[Xícara]

Hi. I'm trying source sodium metaborate here in Brazil where it is called metaborato de sódio. There seems to be two types available: metaborato de sódio 4H2O (tetra-hydrate?) and metaborato de sódio 10H2O. Does anyone know please which I should choose?
Thanks,

 

[MattKing]

What is your intended use for it?

 

[Xícara]

What is your intended use for it?

To make DK-25R. D-23 replenisher

 

[reddesert]

The different hydrations just refer to how many water molecules are attached to each ion when the structure is crystallized (probably from solution in the manufacturing process). Once you dissolve them in water, they should have the same chemical effect, but the molecular weights are different so you would need to convert the weights in a recipe.

I think most photographic formulas are likely using sodium metaborate tetrahydrate, NaBO2 * 4H2O.

I would want to check that the decahydrate is actually sodium metaborate. If it's sodium borate decahydrate, that could be Borax (Na2B4O7 * 10H2O), which is also an alkali but not an equivalent substitute for sodium metaborate.

 

[Xícara]

The different hydrations just refer to how many water molecules are attached to each ion when the structure is crystallized (probably from solution in the manufacturing process). Once you dissolve them in water, they should have the same chemical effect, but the molecular weights are different so you would need to convert the weights in a recipe.

I think most photographic formulas are likely using sodium metaborate tetrahydrate, NaBO2 * 4H2O.

I would want to check that the decahydrate is actually sodium metaborate. If it's sodium borate decahydrate, that could be Borax (Na2B4O7 * 10H2O), which is also an alkali but not an equivalent substitute for sodium metaborate.

Yes, I see. Thanks very much.

 

[bernard_L]

Possibly this helps:

Sodium Metaborate from Borax and Lye

I'm looking to make Sodium Metaborate from Borax and Lye but am confused as to the amounts to be used. The Darkroom Cookbook states that 100g of Sodium Metaborate = 9.5g Lye + 45.5g Borax while I find other references on the Internet that state that 100g of Sodium Metaborate = 14.5g Lye + 69g...

www.photrio.com

and this:

Kodak / sodium metaborate

At some stage long ago, I made a note of Kodak advice that in place of 10g Kodalk (sodium metaborate) one could use 1.5g sodium hydroxide plus 7g borax. So this is what I have been using in bath B of Barry Thornton's two-bath developer (so 1.8g NaOH plus 8.4g borax in 1 litre of solution), and...

www.photrio.com

 

[Xícara]

Possibly this helps:

That helps a lot, thanks. A quote I just got back for 500g of sodium metaborate tetrahydrate was exorbitant!

 

[pentaxuser]

That helps a lot, thanks. A quote I just got back for 500g of sodium metaborate tetrahydrate was exorbitant!

There is a way to make it from other ingredients Here's the video



Of course it relies on the availablity of the chemicals mentioned in the video in Brazil but hopefully they are cheaper and easier to get hold of than Sodium Metaborate

pentaxuser

 

[Xícara]

There is a way to make it from other ingredients Here's the video

Excellent video. Thank you. Will definitely make a solution. All I need for metaborate and to make D23, is some sodium hydroxide. Very easy.