DK-25R question

Xícara · Jun 28, 2024

Hello again,

I wish to make up DK-25R to replenish D-23 but have run into a problem. I was wanting to use the following formula to make 500ml of the stuff:

350ml Water at 52°C
Pinch of sodium sulphite
Metol – 5g
Sodium Sulphite – 50g
Sodium Metaborate – 10g
Water to Make 500ml

The formula is from the following page (adjusted for 500ml): https://www.kabbottphoto.com/developing-black-and-white-film-with-d-23/

Unfortunately, pure Sodium Metaborate has shown itself to be a luxury item here - just too expensive, so as suggested by @pentaxuser , I looked to John Finch's video:

This video shows how to make a solution where each 40ml contains 1g of Sodium Metaborate. The formula in the video, if I'm not mistaken is:

300ml or so of water at 52°C
Borax 7g
Sodium Hydroxide 1.5g
Water to make 400ml

I initially thought, "that's great", because 400ml contains 10g of Sodium Metaborate, just what's needed for the DK-25R formula.

But obviously, all that extra water is going to mess up the concentrations of Metol and sodium sulphite.

A naive idea would be to substitute the initial 350ml of water at 52°C with the 400ml of Sodium Metaborate solution, raised to 52°C, but I have no idea if that's safe or correct.

Unfortunately, John Finch in another video on making DK-25R, uses the sodium metaborate powder and not a solution.

Does anyone know what to do here, please?

Thanks!

Alex Benjamin · Jun 28, 2024

I got mine directly from Photographers Formulary. Here's a link to the data page (pdf), with the formula.

https://stores.photoformulary.com/content/01-0057.pdf

Alex Benjamin · Jun 28, 2024

I should also have left a link for if you want to order it. It's a bit hard to find on the website, as it's on the same page as their D-25 developer

Formulary D-25

Developer D-25 Film Photography Chemicals

stores.photoformulary.com

bernard_L · Jun 28, 2024

Xícara said:
A naive idea would be to substitute the initial 350ml of water at 52°C with the 400ml of Sodium Metaborate solution, raised to 52°C, but I have no idea if that's safe or correct.

This idea is not only naïve but also correct. The only reason to start with an amount of water less than the intended final volume is that, if you did start with the final water volume, you might fear that adding the powder ingredients would result in a larger final volume.
(a) That would be a small error, a few % at most. The extra volume would actually be welcome to fill partly the void between the nominal volume and the bottle cap. (half joking).
(b) With that said, there is nothing sacred with the 350ml. You can start with 400ml. And rest assured that the addition of the other ingredients of DK-25R will not cause an overshoot beyond 500ml. A few ml beyond 400ml at most. You can check that easily. Then add water to 500ml.

Xícara · Jun 28, 2024

Alex Benjamin said:
I got mine directly from Photographers Formulary. Here's a link to the data page (pdf), with the formula.

Thanks for the quick reply. With shipping, the cheapest option being US$22.06, the sum is US$36.01. Brazil, since the new government, bless them, now taxes everything that comes into the country to the tune of 100% (including the my state's import duty) on goods and shipping (with some exceptions for goods under 50 dollars due to sweetheart deals with certain Chinese markets - Aliexpress for one) . US$71 in the local currency is R$396 - not cheap! It's absurd...

Sorry for ranting. I've purchased PMK in power form from the Formulary in the past, but it's not worth it now. Which is why I'm trying my hand at chemistry. ;-)

Xícara · Jun 28, 2024

bernard_L said:
This idea is not only naïve but also correct. The only reason to start with an amount of water less than the intended final volume is that, if you did start with the final water volume, you might fear that adding the powder ingredients would result in a larger final volume.
(a) That would be a small error, a few % at most. The extra volume would actually be welcome to fill partly the void between the nominal volume and the bottle cap. (half joking).
(b) With that said, there is nothing sacred with the 350ml. You can start with 400ml. And rest assured that the addition of the other ingredients of DK-25R will not cause an overshoot beyond 500ml. A few ml beyond 400ml at most. You can check that easily. Then add water to 500ml.

That's great, thanks. So is it safe to heat the Sodium Metaborate solution to 52ºC?

pentaxuser · Jun 28, 2024

Xicara, the two solutions of D23 stock and the replenisher are made separately and after 3 fílms of using only D23 stock he then adds 22ml of Replenisher each time so each 22ml per film contains a lot less than 10 g of Metaborate which is needed only for many films

Yes the amount of Metol used in the Replenisher is different from the amount of Metol in D23 but they are 2 different solutions so do not affect each other.

Does that make sense or is my logic flawed?

pentaxuser

Xícara · Jun 28, 2024

Thanks @pentaxuser . I'm pretty clear now on using d23 and how and when to replenish. My doubt is to do with making the replenisher using 400ml of sodium metaborate solution and not the powder. But if I make the solution, which is also, heated, and then immediately carry on and make the replenisher (substituting the 350ml of water with the metaborate solution), the solution should still be warm enough to dissolve the metol and sodium sulphite.
Cheers,

Xícara · Jun 29, 2024

Just to confirm. Does this procedure look correct to make 500ml of DK-25R using a sodium metaborate solution?

First the Sodium Metaborate part (and note: I've omitted the addition of water to make 400ml in this first part to avoid cooling the mixture in order to dissolve the chemicals in the second stage - the DK-25R solution).

350ml Water at 52°C
Borax 7g
Sodium Hydroxide 1.5g

Now to make the DK-25R

Add pinch of the Sodium Sulphite below
Metol – 5g
Sodium Sulfite – 50g
Water to Make 500ml

bernard_L · Jun 29, 2024

Xícara said:
Just to confirm. Does this procedure look correct to make 500ml of DK-25R using a sodium metaborate solution?

It is correct : you have the equivalent of 10g metaborate.

Xícara said:
I've omitted the addition of water to make 400ml in this first part to avoid cooling the mixture in order to dissolve the chemicals in the second stage - the DK-25R solution

I don't understand why you don't start with 400ml of water at 52°C (come on, 50°C is close enough) as specified in the recipe for metaborate. Why would you need to cool down something (or avoid cooling down something, unclear). The second part --the other ingredients for DK-25R-- also needs to be dissolved at 125°F/52°C.
Plus, starting with less water than specified (for the metaborate) you run the risk that dissolution will be more difficult.

You should now be all set for D23/DK-25R.

Xícara · Jun 29, 2024

bernard_L said:
don't understand why you don't start with 400ml of water at 52°C (come on, 50°C is close enough) as specified in the recipe for metaborate. Why would you need to cool down something (or avoid cooling down something, unclear). The second part --the other ingredients for DK-25R-- also needs to be dissolved at 125°F/52°C.
Plus, starting with less water than specified (for the metaborate) you run the risk that dissolution will be more difficult.

Thanks. I actually just mixed it up as above and there was no problem dissolving anything. I started the first part with 350ml at 52°C, which is more than the required volume for the metaborate stage but correct for the second stage. I omitted "topping up" the first stage to 400ml, which would have been with water (I used deionised) at room temperature - which I could have heated too but that would be a pain. I then proceeded to the 2nd stage with the solution still not too far below 52°C.

edit - but yes, I could have started with 400ml, you're right - i was just concerned the chemical added might cause an overflow.

Xícara · Jul 1, 2024

I read the following on John Finch's website. It shows, as an option, a much better way to use and make a Sodium metaborate solution, and maintains the correct order in its sequential addition of chemicals, ie. the Sodium metaborate is added at the end. Hopefully my upside-down replenisher will work...

Source: http://www.pictorialplanet.com/advanced_photography/D23.html

DK-25R - D-23 Replenisher

Chemical Amount
Water 52C 650ml
Metol 10g
Sodium sulphite 100g
Sodium metaborate* 20g
Water to make 1 Ltr

*If you can't get sodium metaborate you can replace it in this formula with 14g Borax + 3g Sodium Hydroxide.
- After dissolving the rest of the chemicals calculate how much water will be needed to top up the amount to 1 Ltr.
- Then use this calculated amount at 50C to dissolve the borax followed by the hydroxide.
- Allow to sit for ten minutes with occasional stirring.
- Then add to the other part and mix.

Donald Qualls · Jul 17, 2024

When I've made DK-25R, I formed the metaborate in the in-process replenisher. That is, after adding the pinch of sulfite, the metol, and the rest of the sulfite to the starter water, I then added the borax and sodium hydroxide in the needed quantities directly into the solution. After final mixing, I then made up to volume as usual.

I'd be concerned (possibly without basis) about the alkalinity of the metaborate solution causing problems when adding the metol and sulfite. I don't know that there would be a problem, but I've never seen an issue adding the components that form metaborate last (in order of borax, then sodium hydroxide, to avoid excessive alkalinity) before making up the volume with water.

DK-25R question

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