Progress on XTOL-concentrate

[albada]

Could folks do me a favor and tell me which crop below is grainier? Even if they look the same to you, please post a note so I'll know:

XTOL:

TEA-mod:


The second is the concentrate with some TEA added, and I'm trying to decide if it's worth pursuing this modification. And please don't laugh about the water-spots and dust; I was casual about cleanliness because these are just test-strips. Here are the density-curves:



From a density point of view, the modified concentrate is identical to XTOL. But I'm trying to decide about the grain. For the curious, here's the formula. In my test, I dissolved these directly into water:

Propylene glycol .................... 22 ml
TEA85-DEA15 ....................... 3.4 g (yes, that's grams, = 3.1 ml w/ sg=1.107)
Sodium metaborate 4 mol ..... 3.5 g (dissolves in 3-5 minutes. let sit to dry) (4.9 to cnv AA)
DimezoneS/Phenidone .......... 0.2/0.105 g (DimezoneS dissolves in 3-5 minutes. turns orange)
Ascorbic acid ......................... 8 g (dissolves in 7-10 minutes; fizzes and turns clear)
Propylene glycol to ................ 33.3 ml (final volume; should need to add little)

Heat to 90C to dissolve everything and drive the water out of the metaborate.
Dissolve in the order shown, and dissolve completely before adding the next chemical.
To make one litre of developer, mix 33.3 ml of concentrate into water containing 85 grams of sodium sulfite. That's 1+29 dilution.
Times are same as XTOL. Target pH is 8.32.
Concentration ratio = 11.7/33.3 = 0.35

I took the prior concentrate, reduced the ascorbic acid and sulfite a little, and substituted TEA for about half the metaborate. My first test showed that, all other things being equal, TEA gives greater density than metaborate. Alkalis are not created equal. PC likes TEA.

The TEA, labelled "TEA85-DEA15" above, is from Photo Formulary, and their MSDS states that it's 85% TEA and 15% DEA (or slightly more TEA). I tried it a few months ago, and got frustrated because nothing about this TEA agreed with the spec's: specific gravity, pH in solution, and even the freezing point. Whatever is in there, I'm sure it's mostly TEA, but I think of it as "mystery TEA". I'd want to get another sample before recommending this formula. Actually, I'd prefer to use 99% TEA (and boost the 3.4g a little), but that's harder to get in the USA (but easier in Europe).

@athiril: You have an interesting developer using CD-2. Please post that to a new thread where it'll get more visibility.

@Alan Johnson: Thanks for the confirmation. I'm becoming leery of a concentration ratio over 0.35. Maybe I should mix a 0.40 to see if it crystallizes. I'm wondering what the threshold is.

Mark Overton

[Photo Engineer]

Mark;

The second strip is much less sharp than the first one for whatever reason. Thus it is hard to judge graininess.

PE

[albada]

Mark; The second strip is much less sharp than the first one for whatever reason. Thus it is hard to judge graininess. PE

The camera was misfocussed a little in the second strip, so the boundary lines are soft. But that has no effect on graininess, and the scanner was carefully focussed in both scans, so the grain should be equally sharp in both.

Mark Overton

[Photo Engineer]

I would have to say they are close, but perhaps #2 is grainier.

PE

[Michael R 1974]

While the boundaries are soft in the second exposure, I can't see a meaningful difference in graininess or acutance between the two.

To be honest, I think you might be beyond "direct" visual comparisons at this point - which is to say they are very close. There might still be small differences in image structure between the Concentrate and XTOL, and they might influence the subjective perception of granularity (ie graininess) and acutance in photographs, but to evaluate this more objectively you're into micro densitometer territory (ie RMS granularity).

Just my two cents.

[Athiril]

@athiril: You have an interesting developer using CD-2. Please post that to a new thread where it'll get more visibility.

Will do so when I get more reliable internet.

[john_s]

I'll answer instead of Mark: Photo Formulary sells sodium metaborate which according to their MSDS is sodium metaborate 4 mol. This MSDS lists the formula NaBO₂·2H₂O [Na₂B₂O₄·4H₂O]

Likewise there is a reference on http://www.borax.com which lists both 4 mol (NaBO₂·2H₂O) and 8 mol (NaBO₂·4H₂O) sodium metaborate. So for all practical purposes I would assume that Mark means the 4 mol compounds as defined by these references: NaBO₂·2H₂O

The confusing names seem to come from the double compounds Na₂B₂O₄·4H₂O and Na₂B₂O₄·8H₂O

Confusing naming indeed. More confusing than the usual question of the degree of water of crystallization in compounds like sodium carbonate where at least if it's labeled correctly we get only one version, e.g. monohydrate, decahydrate etc.

So confusing, in fact, that www.borax.com have made a mistake in their product data sheet for the 4-mol. See page two, top right, where 4H2O should read 2H2O.

I wonder which version my sodium metaborate is (bought at Vanbar Melbourne). It didn't matter much with PMK because Part_B was pretty much a saturated solution and some people varied the relative amounts of Part_A and Part_B anyway. But in this interesting concentrated Xtol-like developer I would guess that the pH would be sensitive to errors in the exact amount of metaborate.

[Photo Engineer]

If the pH is correct, then the developer should work properly. The major difference is the buffering capacity. If you figure out the number of moles of boron you want present, then you can make the right mix from boric acid and Sodium Hydroxide.

PE

[Gerald C Koch]

Actually, I'd prefer to use 99% TEA (and boost the 3.4g a little), but that's harder to get in the USA (but easier in Europe).

The Chemistry Store www.chemistrystore.com sells 99% TEA. Since their main clientele use it to make soaps and lotions it cannot contain any DEA or MEA. You can check out the MSDS for the chemical on their site. One gallon sells for $16.84 plus shipping.

[albada]

The Chemistry Store www.chemistrystore.com sells 99% TEA. Since their main clientele use it to make soaps and lotions it cannot contain any DEA or MEA. You can check out the MSDS for the chemical on their site. One gallon sells for $16.84 plus shipping.

You bring up a subject I've been wondering about.
At PhotoFormulary, one gallon of TEA (85%-15%) costs $49.95.
At ChemistryStore, one gallon of TEA (99%) costs $16.81.
That's a much lower price for a better product.
So I suspect that the 99% in the ChemistryStore's MSDS is a mistake.
Or how could they sell a high-grade product so cheaply? What do you think? Have you found that their TEA behaves like 99%? If so, I'm buying some now!

@PE: I feel silly asking this, but is buffering capacity determined by the number of boron atoms, or by the number of molecules of borate? If it's by the number of boron atoms, we could substitute one fourth the moles of borax (vs metaborate) because one borax molecule contains four boron atoms (vs one boron atom in metaborate). Relayer would be interested in this.

Mark Overton