Stain with Xtol

sanking · Aug 13, 2006

I am doing some tests involving Xtol and just by chance checked the densities of step wedge prints on FP4+ and Delta 100 in both Visual and Blue mode. Turns out that Xtol gives a pretty good stain. For example, where the density at Step 1 was 1.74 in Visual mode, it was 1.98 in Blue mode.

Just wondering if those who use Xtol with VC papers have noticed any printng differences between it and a developer like D76 which produces no stain? Does this amount of stain result in any highighlight compression?

Sandy King

Ryuji · Aug 13, 2006

I wouldn't call it stain. It's just that absorption spectrum is not neutral grey. Even visually, negatives developed in my fine grain ascorbate developers look brownish. This is most likely because of finer grains and perhaps some other differences in the morphology of the grains.

Mark Layne · Aug 13, 2006

I will look again but have never noticed any 'brown' on my xtol TX negatives.

With some 40 year old Efke film it gives a perfectly clear base where other developers give a high fog level.

Jordan · Aug 13, 2006

The oxidation product of ascorbic acid is formally a 1,2,3-triketone (which would exist as a kind of hydrate in aqueous solution). Structurally, this shares some features with the oxidation products of catechol and pyrogallol. I am not an expert on staining but I seem to recall that the stain consists of imines formed between lysine side-chains in the gelatin protein chains and the quinones formed after oxidation of catechol or pyrogallol.

I'm in the realm of chemical speculation here, but it is conceivable that the ascorbic acid oxidation product could cross-link to gelatin in the same way that the catechol and pyrogallol oxidation products do. I don't know how much more or less "stable" the cross-link would be. Ryuji, I'd appreciate your input on this one.

Ryuji · Aug 13, 2006

Jordan said:
The oxidation product of ascorbic acid is formally a 1,2,3-triketone (which would exist as a kind of hydrate in aqueous solution).

You are talking about DHA. Dissociated ascorbate gets oxidized to a radical form and further oxidation makes it (reversibly) to DHA. As you said, in water much of it is in DHAA form, or even diketo-gluconate form, which can further break down to different acids. One consideration is whether DHA is generated at an appreciable rate during development. Another consideration is whether its potential crosslinking reaction is at competition with other reactions and diffusion. Yet another consideration is whether this triketone is an effective crosslinker at pH of 8.2 and 20C. Yet another consideration is whether the crosslinked gelatin molecules show greater blue absorption. I'll have to think about these factors. No immediate answer that can satisfy you.

But in experience, I do not have any case where I saw tanning of gelatin in XTOL-type developers.

With your amino group theory, it is easy to block 99+% of the lysine residue by acylating the gelatin first. Trimellitic anhydride, phthalic anhydride and other acid anhydrides or chlorides can be used. I've always done this reaction with aquaous phase of gelatin, but it can probably be done on hardened coating (say fix T-MAX 100 with no development, acylate the amino groups and then see if it makes difference in your hypothesis).

Another possibility is to use an inhibitor of your hypothetical reaction by taking away the triketone. One possibility may be to add amines that are more reactive than lysin residue... and see if they steal the reaction. I've tried a LOT of different amines in ascorbate developers but I'm afraid none of them would answer this question. Need differnt ones.

Ryuji · Aug 13, 2006

Oh simpler way to prove is to bleach silver image on ascorbate-developed films and measure blue density... but of course you can't get away from the question whether the bleach did something to the stain image...

Tom Hoskinson · Aug 13, 2006

I've been curious about this general subject.

Last month, I saw a brownish stain and then I measured significant blue channel densities (And visual channel densities) on a Efke Test film while I was checking the activity of one of my stock developer concentrates. The concentrate compositon is Metol and Ascorbic Acid dissolved in Triethanolamine. The Alkali I used in this test was Sodium Carbonate. I used no Sodium Sulfite .

Ryuji · Aug 13, 2006

Tom, does that happen with any film from Fuji or Kodak?

What's the exact composition, pH, other conditions of your experimental developer? (if there's no secret there)

TimVermont · Aug 13, 2006

I've been wondering about this myself for a little while. Here is the data I have, if it helps, great. The effect is very consistent and repeatable on APX 25 (yes, I have a lot in the freezer), 6m00s in XTOL 1+3, constant rotation in a JoBo, 24c. The density reads the same in visual or UV mode for the low densities, but then a visual 1.00 reads 1.05 in UV and the difference increases- a visual 1.39 reads 1.54 in UV mode.

Tom Hoskinson · Aug 13, 2006

Ryuji said:
Tom, does that happen with any film from Fuji or Kodak?

What's the exact composition, pH, other conditions of your experimental developer? (if there's no secret there)

I mixed this stock concentrate in 2004. This was a quick test to see if the concentrate was active.

Stock Concentrate A

1. Warm Triethanolamine (about 140 deg. F)------------350 ml
2. L-Ascorbic Acid--------------------------------------48 grams
3. Metol-----------------------------------------------6 grams
4. Dissolved all dry ingredients
5. Added Warm Triethanolamine to make--------------500 ml

Stock Alkali Solution B:

1. Warm deionized water (about 125 deg. F)-------------------100 ml
2. Sodium Carbonate monohydrate--------------------75 gm
To make working developer for the activity test I added 15ml Stock Concentrate A and 15 ml of Stock Alkali Solution B to 100ml Deionized water.

I did not check the pH of the concentrates or the pH of the working developer. However, I can easily do that.

I will also run a test on Kodak TMAX 400.

My (semiconductor grade) deionized water is from my lab filter chain (continuously monitored 18 megaohm water).

Ryuji · Aug 14, 2006

Ok people, I'll have to repeat:

Observation of higher density with blue or UV than average visual spectra does not mean that there is stain image. Same silver image can produce different optical density depending on the wavelength used to measure the density. For example, warmtone prints' image scatters more blue light than red, thus greater blue density.

As I said before, it is not uncommon to see slightly brownish image on negative films when developed in certain fine grain developers such as XTOL. This can happen without any stain image. If one argues the presenbce of stain image, this possibility must be excluded.

Ryuji · Aug 14, 2006

Tom Hoskinson said:
I mixed this stock concentrate in 2004. This was a quick test to see if the concentrate was active.

So...

100-115ml/L triethanolamine, 11g/L ascorbic acid, 1.4g/L Metol, and 87g/L potassium carbonate.

Is this right? Umm...

sanking · Aug 14, 2006

Ryuji said:
Ok people, I'll have to repeat:

Observation of higher density with blue or UV than average visual spectra does not mean that there is stain image. Same silver image can produce different optical density depending on the wavelength used to measure the density. For example, warmtone prints' image scatters more blue light than red, thus greater blue density.

As I said before, it is not uncommon to see slightly brownish image on negative films when developed in certain fine grain developers such as XTOL. This can happen without any stain image. If one argues the presenbce of stain image, this possibility must be excluded.

Whether the blue absorption is due to stain or to some other kind of phenomenon the fact remains that the intensity is not insignificant and could be enough to play a role in the way such negatives print. It certainly plays a role in sensitometry. Plotting Xtol negatives with Visual reading gives different curves than plotting with Blue readings, unlike other developers such as D76, HC110 and DK50 which give perfectly neutral tone readings.

Sandy

Claire Senft · Aug 14, 2006

I tend to think along the same lines a Mr. King. If I were to use Xtol for developing negatives and I had in my a particular density range as being suitable for printing on a given paper than I would expect that readings taken with out considering the differences in light transmission I would find that my negatives were not printing as I expected them to print.

In fact, since the color of the negative developed that produced a warm silver image should be very archival, it might be a better choice then a stained negative were the stain may be of a somewhat transient character.

Kirk Keyes · Aug 14, 2006

You guys probably don't remember, but either last summer or the summer before I posted in a thread here on staining developers, I mentioned that if you bleach an XTOL neg, you will get a magenta image. It's very low in density - something like 0.05 max density, but plainly visible.

I agree with Ryuji that it's a warm tone silver image, and not a stain.

But you are right about it possibly having an effect - if your printing process uses densities that are high enough that the B or G densities start to deviate significantly.

nworth · Aug 14, 2006

Ryuji said:
Oh simpler way to prove is to bleach silver image on ascorbate-developed films and measure blue density... but of course you can't get away from the question whether the bleach did something to the stain image...

If the stain from the bleach is a problem, you could compare similar images bleached from film developed in ascorbate and in a known non-staining developer.

Ryuji · Aug 14, 2006

nworth said:
If the stain from the bleach is a problem, you could compare similar images bleached from film developed in ascorbate and in a known non-staining developer.

No, the problem is more on the possibility of bleach destroying the "possible" stain image.

Ryuji · Aug 14, 2006

Kirk Keyes said:
But you are right about it possibly having an effect - if your printing process uses densities that are high enough that the B or G densities start to deviate significantly.

I think people empirically know that negatives developed in DS-10 or XTOL may appear slightly thinner to the eye but they print well.

Whether it indeed has influence on multicontrast paper stock, I haven't tested. Maybe I can compare Brovira Speed and Agfa Multicontrast... but the measured density steps would have to be compensated for different curves of the paper emulsions. All these can be done but not very high on my priority list right now...

Stain with Xtol

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