(Instant) Mytol - thin negatives

PieterB · Jan 13, 2021

I am successfully mixing my own developers such as D23, D76, Pyrocat HD (in glycol)

However, I tried to mix a few 'known' ascorbic acid formulas because of Xtol packaging problems
I do not want to be completely reliant on batches of chemistry coming from China...

- E-76 --> very high base / fog (?)
- Mytol --> very thin negatives but i was suspecting the use of ascorbic acid instead of sodium ascorbate ....
- Mytol instant --> again very thin negatives, barely usable.
Measured pH was 8,1 / 8,2 so that seemed to be right.

Which chemistry or mixing fault is probably the reason of this thin negatives?
- phenidone oxidized somehow? (light yellow colour)
- phenidone not properly dissolved ?
- ascorbic acid oxidized?

Any straight-forward way to test this chemistry?

Thanks a lot!

grain elevator · Jan 13, 2021

Did you use asorbic acid to directly replace ascorbate the recipe called for? That's not how it works and would explain your issue. You can use ascorbate and an alkali to make ascorbate (the necessary calculations are beyond what I remember from highschool chemistry class), but I believe I've seen Mytol recipes with ascorbic acid.

PieterB · Jan 13, 2021

The 'instant' mytol recipe is specifying more generally available ascorbic acid. But I still had the very thin negatives.
I ordered some new as wel as methyl hydrate to dissolve the phenidone more easily.
Hope that will help ruling out possible causes.

What I am also not sure about is adding KBr or not....

If that still doesn't work, D76H will be my default recipe.... as it also contains no Hydroquinone and is very easy to make after all....

grain elevator · Jan 13, 2021

I see. I can't help with your concrete questions, but one more thing to rule out: You did use the instant Mytol instantaneously? Because if you wait, it can break down.
Actually I'd also love to know if (or in what time frame) ascorbic acid and phenidone will oxidize, the containers mine came in don't seem absolutely airtight.

Lachlan Young · Jan 13, 2021

The Fenton Reaction is likely the cause of your issues. It is a well known problem with ascorbate developers. You need quite specific chelating agents to deal with it - DTPA I recall - not EDTA.

grain elevator · Jan 13, 2021

I believe the reason why it's called Instant Mytol is that when used instantaneously, it works, despite no chelating agents; it takes a little while for the Fenton reaction to take place. Hence my question above.

Lachlan Young · Jan 13, 2021

grain elevator said:
I believe the reason why it's called Instant Mytol is that when used instantaneously, it works, despite no chelating agents; it takes a little while for the Fenton reaction to take place. Hence my question above.

I suspect it may also be quite dependent on the specific water quality used, and how long it sat before being used. 'Immediate' can be quite a flexible term...

138S · Jan 13, 2021

PieterB said:
Which chemistry or mixing fault is probably the reason of this thin negatives?

If no error in the mixing, as pH was checked, then we may blame the developing agents, ascorbate or phenidone could be bad.

I had used The Darkroom Cookbook 3rd Ed. formula, for perfect yield.

Water at 80F/27C, 750.0 ml
Sodium sulfite, 85.0 g
Sodium metaborate, 4.0 g
Sodium ascorbate, 12.0 g
*Phenidone, 0.15 g
Sodium metabisulfite, 3.0 g
Water to make 1.0 liter
* Dissolve the Phenidone in 5.0 ml of methyl hydrate (methanol) and then add to the solution

There are several variants but result would be the mostly identical.
https://www.photrio.com/forum/threads/will-the-real-mytol-please-stand-up.84293/

I often use deionized water to mix both Xtol and Mytol. For long term storage I prefer Xtol, and Xtol mixed with deionized water.

IMO water quality may only concern to the shelf life, if iron content in tap water is high then Ascorbic can be damaged in the mid term, but this won't be noticed just afer mixing Mytol.

PieterB said:
Any straight-forward way to test this chemistry?

Do a Drop Test. Take a film end, lights open throw a drop of developer every (say) 1min, in separated places of the film end. After some 10min Stop and fix the film end, see the density obtained under each drop.

Compare to a Drop Test made with Xtol.

koraks · Jan 13, 2021

Instant mytol is currently my main (actually, virtually only) B&W developer. I think it's great. I mix it with tap water, with no chelating agent. I generally use it one shot and immediately after mixing. I haven't noticed any issues in this use case. Neither did I notice any particularities when re-using a solution after a few days, but I haven't done any longevity tests.

PieterB said:
What I am also not sure about is adding KBr or not....

I never do this.

As to the phenidone: mine is very pale yellow as well. But I never add it in its dry form directly to the mytol. It takes a while to dissolve and it's easy to make a measurement error with the very small quantities involved. Instead, I keep a 1% 'stock' solution of phenidone in porpylene glycol around, which is overall so much more convenient to use - and it lasts quite long as well. I usually mix something like 25ml (yes, a tiny amount), which keeps well for a year and by then it's all used up anyway. So it may in fact keep even longer.

It's hard to pinpoint a specific problem in this case; if I were to guess, I'd put my money on incompletely dissolved phenidone. Alternatively some kind of mixing/calculation error could also play a part, but that's kind of difficult to figure out.

IMO this developer is worthwhile to troubleshoot. If it works (I never had any particular issues with it), in my opinion it gives excellent results with all films I've tried in it so far. And it's relatively environmentally friendly, which bumps the feelsgood-factor.

osella · Jan 13, 2021

My phenidone is also pale yellow, also provided it and the ascorbic acid stay dry I believe the shelf life is quite long. They both oxidize quite rapidly in solution though.

You can’t directly substitute ascorbic acid for sodium ascorbate, as the pH will be different. If you want an xtol like developer with ascorbic acid there is always PC-TEA.

koraks · Jan 13, 2021

osella said:
You can’t directly substitute ascorbic acid for sodium ascorbate, as the pH will be different.

This can be easily overcome by increasing the amount of carbonate. I always use ascorbic acid instead of ascorbate.

Lachlan Young · Jan 13, 2021

michael_r said:
Apparently the Fenton reaction can be quite fast so I don't know if "instant" Mytol necessarily fixes the problem.

I think it may only take a small rise in iron and/or mixing temperature to really speed up the reaction - the iron is the catalyst from what I recall.

osella · Jan 13, 2021

koraks said:
This can be easily overcome by increasing the amount of carbonate. I always use ascorbic acid instead of ascorbate.

I mentioned it because it seemed that he substituted them, and it might have been a cause.

Is there a mytol formula with carbonate? I might try that some time as I have everything else I need.

koraks · Jan 13, 2021

I posted my formula at some point; I'd have to dig it up, but it's borax, sulfite, sodium carbonate, vitamin C & phenidone.

Peter Schrager · Jan 13, 2021

Instant Mytol
750ml water heated to 125 degrees F
60g sodium sulfite anhydrous
11.5g Ascorbic Acid
0.15g Phenidone that I dissolved in 50ml pure alcohol
13.4ml Tea heated to about 110 degrees F
Water to 1 liter
I mixed this up for the first time the other day and got near identical results to Xtol
I have no clue as to keeping results but imagine if I did the same as Xtol and filled my glass bottles to the brim it might last well...can't verify this
there are several versions of this but I chose this one for simplicity.

PieterB · Jan 13, 2021

Hi,

Thanks for all replies. In the meantime I was not following up, working with the chemistry instead ;-)
I believe my problem is solved by first dissolving the phenidone in propylene glycol as a 1% solution.
It really needed ~5 to 10 minutes while heated to properly dissolve; so probably this was not the case before

I used this custom 'pc-brew' ; with a dev time between stock xtol and 1+1
400 ml destilled water
8 g sodium sulfite (anhydrous)
2,5 g sodium carbonate (anhydrous)
5 g Vit-C
6 ml of the 1 % phenidone stock
add destilled water for 500ml

The next step is standardisation with the known (Instant) Mytol recipe and in comparison with D76-H
What are you experiences in comparison with commercial, of-the-shelf dev?
Anyone uses 1+3 dilution with an own vitc dev, especially if using sodium metaborate instead of TEA?

Anon Ymous · Jan 14, 2021

michael_r said:
You can also convert ascorbic acid to sodium ascorbate with some sodium bicarbonate and isopropanol.

This is probably easier said than done and some more details are needed.

relistan · Jan 14, 2021

koraks said:
Instant mytol is currently my main (actually, virtually only) B&W developer. I think it's great. I mix it with tap water, with no chelating agent. I generally use it one shot and immediately after mixing. I haven't noticed any issues in this use case. Neither did I notice any particularities when re-using a solution after a few days, but I haven't done any longevity tests.

I have 3.25 year old PC-Glycol that still works fine. It has a bit of precipitate but doesn't seem to have weakened too much. I can see it's getting too old and I need to make a new batch (these are warning signs) but 1 year is definitely conservative, if it helps.

PieterB · Jan 15, 2021

Can sodium metaborate / Kodalk be a reason of Instant Mytol failure with thin negatives appearing underdevelopped.
Exposed film (leader) is also quite transparant and not black

I mixed some PC-Glycol and I can't distinguish the drying negatives from those with reference developer D76H
(testfilm: foma 400, 7 minutes @ 22 degrees C)
So that rules out the phenodine and vit c (which I don't expect to fail anyhow)

For the Instant Mytol mix,
Start with 750 ml water
60 g sodium sulfite (anhydrous) --> OK
11.5 g ascorbic acid --> OK
0.15 g phenidone --> I took 15 ml of 1% Phenodine dissolved in glycol
13.4 ml triethanolamine or 7 g sodium metaborate

This stock I used to create 1+1 working solution with the same times as xtol 1+1
So it's either:
- phenidone concentration
- sodium metaborate not used/stored properly (would be strange)
- dev time / mix

As I ruled out the other variables, I must be doing something wrong here resulting in very thin negatives
The first self-made developer I have complete failure with ;-)

koraks · Jan 15, 2021

Did you measure the pH? You're using ascorbic acid and metaborate; most of the metaborate will react with your ascorbic acid, shifting the pH downward. I'd be surprised if this recipe would give a pH of 8.20.

PieterB · Jan 15, 2021

PH was to low indeed about 8.0 measured after I throwed it away. But it is the instant recipe mentioned on two different places...

koraks · Jan 16, 2021

You could try this (for 1000ml):

Borax	1.4
Sodium sulfite	60
Ascorbic acid	11.5
Sodium carbonate monohydrate	5.6
Phenidone	0.15

All quantities in grams.
Dissolve in the order shown. I always heat a little water (let's say 50ml heated to 50-80C or so) and dissolve the borax in this, which is quicker than waiting for it to dissolve at low temperatures. Then add more water and mix in the other ingredients, one by one, until they're completely dissolved.
As said earlier, instead of adding dry phenidone powder, I use a 1% solution in glycol.

pH should be 8.20. If it's too low, add drops of a 10% NaOH solution until you hit the mark. If it's too high, add drops of acetic acid (I use cleaning vinegar, which is around 8%) until desired pH is reached.

I never mix a liter all at once but instead mix the amount I need, which is usually 150ml.

radiant · Jan 16, 2021

koraks: what is the most suitable way to get these chemicals in Europe? Ascorbic acid I have plenty

koraks · Jan 16, 2021

I don't know about the borax; I got mine from my dad who got it from a brewer's supply store. But I understand it's officially no longer available to consumers, at least where I live. The sulfite I get from a food supplies store (they sell spices and food additives). But a shop I found that retails solvents also carries it, as well as propylene glycol. The carbonate I get from the supermarket. Phenidone I got from a domestic chemicals supplier. It was relatively expensive, but 50 grams will last me loooong. Ebay is also a good source. Long story short: just shop around a bit...

grain elevator · Jan 16, 2021

michael_r said:
Phototechnik Suvatlar is good. I’ve bought things from them in the past. I don’t think they have an online shop but I believe you can get to them through Moersch.

You can also order from suvatlar by email. And it's worth asking for chemicals that are not in the price list you can download from Moersch!

(Instant) Mytol - thin negatives

PieterB

grain elevator

PieterB

grain elevator

Lachlan Young

grain elevator

Lachlan Young

138S

koraks

Moderator

osella

koraks

Moderator

Lachlan Young

osella

koraks

Moderator

Peter Schrager

PieterB

Anon Ymous

relistan

PieterB

koraks

Moderator

PieterB

koraks

Moderator

radiant

koraks

Moderator

grain elevator

(Instant) Mytol - thin negatives

Moderator

Moderator

Moderator

Moderator

Moderator

Moderator

Privacy & Transparency

Privacy & Transparency