DD23 using Sodium Metaborate Tetrahydrate

[Andrew Forrester]

I use DD23 as a one shot developer at 1 to 1 when processing 120 film with my Jobo, unfortunately I have used all my Sodium Metaborate. I'm in the UK and I have only been able to get some Sodium Metaborate Tetrahydrate via eBay.

I use the late Barry Thornton's version of DD23 and Bath B uses 12g of Sodium Metaborate per 1Lt .

I'm no chemist so I am seeking guidance on whether I should use the same amount of the new chemical or more or less?

 

[rst]

I always use sodium metaborate tetrahydrate (12g/l) when mixing Bath B. Never ran into an issue with it.

Cheers
Ruediger

 

[Ian Grant]

You can make a 10g/l solution from 7gm Borax and 1.5g Sodium Hydroxide, the difference in weight is equivalent to the tetrahydrate form

Ian.

 

[juan]

Some people use borax in the B solution.
http://unblinkingeye.com/Articles/DD-23/dd-23.html

 

[Doremus Scudder]

As far as I know, sodium metaborate tetrahydrate is the common form of this chemical and likely what you've been using in the past. The Photographer's Formulary product is the tetrahydrate. I've been unable to find other forms commonly available through photo chemical supply houses. Just use as usual.

BTW, "tetrahydrate" just tells you how many water molecules are attached to each molecule of the chemical, i.e., four.

Best,

Doremus

 

[Gerald C Koch]

You can also use sodium sesquicarbonate which is easily formed from sodium bicarbonate and sodium carbonate monohydrate. Use 4.0 g of bicarbonate and 6.0 g of carbonate. This forms 10 g of the sesquicarbonate. A 1% solution provides a pH of 10 for bath B and may be useful for countries where sodium hydroxide and sodium metaborate are hard to obtain.

Yes sodium sesquicarbonate is a real compound formed from an equal molar mixture of the two salts. It crystallizes as needles from a water solution.

 

[sfaber17]

I have a box of "Calgon" water conditioner that is just sodium sesquicarbonate. Calgon used to be sodium hexametaphosphate but phosphates were discouraged for washing so it evolved to the sesquicarbonate. It has some particulates like ground cardboard you may have to filter out. It is a good pH buffer alright.
If you use borax for part B (which I do), then don't let it get too cold (somewhere below 65 deg F I think) since if it starts crystallizing, it won't re-dissolve. Make some fresh if that happens.

 

[Gerald C Koch]

I have a box of "Calgon" water conditioner that is just sodium sesquicarbonate. Calgon used to be sodium hexametaphosphate but phosphates were discouraged for washing so it evolved to the sesquicarbonate. It has some particulates like ground cardboard you may have to filter out. It is a good pH buffer alright.
If you use borax for part B (which I do), then don't let it get too cold (somewhere below 65 deg F I think) since if it starts crystallizing, it won't re-dissolve. Make some fresh if that happens.

The contents of the Calgon box is probably sodium sequicarbonate dihydrate as it is the most stable form under customary conditions.

 

[bernard_L]

You can make a 10g/l solution from 7gm Borax and 1.5g Sodium Hydroxide

That sounds interesting, since I have both. But, how critical is the proportion? What I mean is: suppose I would make a sodium chloride solution by combining the theoretical proportions of NaOH and HCl into pure water, the smallest error would send the pH way off from the theoretical value 7.0 (at 20°C). In other words, is Sodium metaborate on a buffer plateau?

 

[sfaber17]

You can also use sodium sesquicarbonate which is easily formed from sodium bicarbonate and sodium carbonate monohydrate. .. A 1% solution provides a pH of 10

Gerald, do you know a formula for a ph 10.0 buffer? I can't find an NBS formula for one. The sesquicarbonate is more like 9.9 unless perhaps your higher dilution gets you to 10.0?

 

[Gerald C Koch]

I have seen several sites which do list some buffers. However I don't have any information on hand.

I rounded the pH off to 10 since its use as bath B is not that critical.