Problems with PMK solution B

[Doremus Scudder]

I added 1l of distilled water to solution B and the chemical did not dissolve.
The pH value is at 8.5 but the pH-meter is a cheap one so I can't count on it.

Something wrong with the sodium metaborate then.

A 30% solution of Sodium Metaborate is supposed to have a pH of around 12 according to borax.com .
A PMK working solution should have a pH of 9.6-9.7.
If it is as low as 8.5, it is not Metaborate and such a pH suggests borax which is a self-buffer around that pH which also explains the solubility issue (less than 100g/L at room temperature)

Hmmm... Did someone mistake sodium metaborate tetrahydrade for sodium tetraborate? Sounds like borax to me.

I had a call with Mr. Suvatlar - he tested the metaborate and agreed that the metaborate contains unsolvable parts (probably because of some reaction with the moisture). I get a refund + 500g working metaborate.

Good for him. At least he stands behind his products.

So... so I don't have a metaborate either

Probably not. Mr Suvatlar seems to be manufacturing his own sodium metaborate from borax and sodium hydroxide. That's fine as long as he tests his results regularly!

Doremus

 

[eli griggs]

Not too long ago, I also took from Suvatlar metaborate. It is in rather large, very hard lumps. I have some doubts whether it is not too much impurities or whether it is metaborate at all. Unfortunately, I don't know how to test it...

I suggest you and other photographers in darkroom include a medium sized porcelain mortar and pestle for breaking out this lumps and grinding non-poisons, with mask and eye protection.

I've run across some really hard lumps in chemicals, that were and always kept air tight, from the supplier, and hitting them is not a good option, in my opinion.

The larger metal mortar and pestles might be fine but, I don't generally like metal on chemical contacts.

 

[eli griggs]

I added 1l of distilled water ro solution B and the chemical did not dissolve.
The pH value is at 8.5 but the pH-meter is a cheap one so I can't coint on it.

A good basic lesson here on buying kit.

If the tool you can buy will not do the job, wait until you can save the price of one that will.

I know that's a stupid simple "rule of thumb", no beaten women here, but in the excitement of adding to your kit, some things have to wait.

In this case, good dip ph test strips will serve and you can upgrade to electronics later, when better able to make the buy.

IMO.

 

[eli griggs]

Yup, that'll do it. Not particularly dangerous, nor difficult.
Borax is easy to obtain also for private individuals in Germany. It's used for certain crafts; if you google around, you'll find plenty for sale. Cheap, too.

Twenty Mule Team Borax is just fine in my experience, for Borox, unless, like so many other things, the Borax manufacturer adds adulterants, ie, 'for a fresh, clean scent' or other such rubbish.

 

[xkaes]

Since the A & B stock solutions are concentrates that are substantially diluted in order to use -- 1:2:100 -- one alternative is to just make working solutions instead of concentrates. One solution is a working solution. That's what I do anyway.

 

[olk]

I made solution B from Borax and sodium hydroxide - clear solution and PMK changes the color from pale green to pale amber. Fomapan 100@50 shows nice green stain. So I will stay with this version of solution B.

 

[xkaes]

Patent it, and make a killing!!!