Sodium Metaborate (KodalK) Solution

I have just returned to BW wet darkroom photography I am using Barry Thornton' 2 bath developer. Is is possible to make a saturated solution of the 'Dev B' - sodium metaborate?

 

Thank you

Yes. A solution of around 20% w/v will be close to saturated at room temperature (~ 20 Celsius). But a true saturated solution would crystallize out at any lower storage temperature, and isn't a good idea.

 

Personally I'd go with a 10% w/v solution that makes the maths easy and has very little risk of crystallising.

 

Sodium metaborate can be easily created in solution by the addition product of equimolar amounts of Boric acid and Sodium hydroxide. Both of which should be readily and cheaply obtainable.

 

Unfortunately that's only true outside of the European Union, which has put a blanket ban on the public sale of Borates on almost zero evidence of any real hazard.

Thank you for this useful information. A 10% solution sounds promising.

 

Dennis

Joe, is boric acid even gone from contact lens solutions? I'm not sure what a good replacement would be in that context...

Just search for metaborate on ebay.

"Joe, is boric acid even gone from contact lens solutions?"

- I wouldn't know Ben. I was surprised to find that both Borax and Boric acid are no longer freely available from hardware stores, and a pharmacy didn't stock Boric acid for public sale either. Stupid EU regulations!

 

There's a "borax substitute" (not) that's a mixture of sodium carbonate and bicarbonate. AFAIK the blanket ban on borates is across the board due to a supposed exposure hazard (unsupported by evidence) to factory and packaging workers. The fact that they'll be put out of work doesn't seem to cross the minds of uneducated bureaucrats.