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dyetransfer
04-01-2012, 12:50 PM
Ron and Jim, I thought a Thorium salt was needed just to enhance sharpness not to actually hold the dye in the receiving gelatin?
Jim, when you say using bleach as in the old wash-off relief process-is this an etch-bleach process?
thanks

I don't remember what the bleach was, but it was a silver bleach which removed the silver image and hardened the gelatin as a result.

- Jim

dyetransfer
04-01-2012, 12:57 PM
T-Grain;
Thorium also altered the hue of the cyan dye a tad. Jim probably has more on that.

PE

Thorium mordanted paper causes a shift towards green of the Cyan dye, immediately as the matrix contacts the paper. With Aluminum mordant, no shift occurs immediately, but it does hue shift upon drying. The Aluminum mordant (M1) actually seems to have much more capacity to shift the hue in dense areas, whilst the Thorium in the Kodak paper looses its ability to shift hue in denser areas.

- Jim

wildbillbugman
04-01-2012, 04:27 PM
I wonder if the bleach contained in E6 developing kits would work? Or maybe just plain old ferric chloride?
Bill

Photo Engineer
04-01-2012, 04:28 PM
I think it might have been the old dichromate bleach.

PE

wildbillbugman
04-01-2012, 08:33 PM
What is the formula for dichromate bleach?
Bill

Photo Engineer
04-01-2012, 09:30 PM
AAAAAAAKKKKKK. You had to ask that.

OTOMH, it would be 50 g/l Potassium Dichromate and 50 - 100 ml / L of 37% Sulfuric Acid (battery acid). Just a guess, but more dilute is ok it just takes more time.

PE

holmburgers
04-02-2012, 10:43 AM
...I am afraid these PVA matrices simply won't work. The reason is simple: they don't have the amino groups present in the gelatin. The dyes (in their ionic form) are attracted to the protonated amino groups (gelatin), so that's why they are held in place even when you rinse the matrix in acetic acid solution. When you make the contact with the receiving paper, there is a gradient in pH between the matrix and the receiving gelatin, so the dye molecules are driven there. Simply put, the dye molecules are more attracted to a gelatin environment with pH 6 rather than about pH 4...

This sounds like a very good assessment of the situation, specifically regarding the amino groups. Not something I know much about, but definitely, the DT mechanism relies on a special relationship between certain types of dyes & gelatin protein.

And regarding,
I thought a Thorium salt was needed just to enhance sharpness not to actually hold the dye in the receiving gelatin?" That is certainly my understanding as well. I've transferred magenta dye to a fixed-out (non-hardening) FB paper and the density is very good, but diffusion is terrible! The mechanism of imbibition though, relies on this pH gradient and not a mordant.

Speaking of which... you can buy thorium nitrate on eBay for fairly low prices. Not that I'm even considering such an endeavor..

DREW WILEY
04-02-2012, 12:40 PM
I have personally used uranyl nitrate mordant with and without aluminum, with the combined effect being a bit sharper. Depends on the receiver paper. But I'd have to defer to Jim's experience on that point. Regarding the use of pigment directly in the relief film and opacity, the hypothetical solution is
much finer pigments which in effect behave as if they were more transparent in relation to saturation. This can be done, but I've already got way to many irons in the fire to do the testing myself per ideal process colors. The carbon printing crowd seems completely unaware of some of the
significant advances in pigment technology which might be applicable. But nothing at this point has
been marketed for process work per se, so there are chroma issues (but nowhere near as bad as back which things like alizarin crimson and poison green were used). One more test which will have to
wait till I retire.

holmburgers
04-02-2012, 01:05 PM
You guys are talking about a kind of Duxochrome thing, eh?

Hexavalent (Ian) has been toying with this idea I think, on the spurring of CMB.

But if hardening is such an issue with polymers, I just fear that none of these schemes will apply well. It makes little sense to set out learning guitar with one hand tied behind your back, or trying to build a car that doesn't use wheels.

Of course finding a way to do it with PVA would be a really great contribution, but gelatin & in turn leather have been utlized for centuries because of its unique property to tan. I'm not sure we should expect a polymer to have any of these same characteristics.

DREW WILEY
04-02-2012, 03:18 PM
From the nature of the bleach involved it looks like Duxochrome involved dyes, not pigments. (???)

wildbillbugman
04-02-2012, 03:18 PM
Guys,
I must admit that I now feel foolish for starting this thread on a subject about which I know little.(Dye Transfer) That takes care of the Matrix Film as far as I am concerned. On the other hand, Jim's idea of loading pigment into panchro emulsions, be they gelatin or polymer based, is still of great interest to me. After I make my next batch of emulsion I will do some initial testing using commercial pigment despersions. If that works out, great. But if light transmision proves to be a problem, I have many years of "proffesional" experience in pigment dispersion for for photoresists. I am familiar with what Drew is talking about. I might actualy purchase a benchtop three-roll mill.
Once I have begun I will begin posting results here. But. That will be at least three weeks from now.
OTOH , someone could decide to pursue matix film and receiving medium based on gelatin emulsions. Why not?
Jim already has the matrix formula published. Bill

Photo Engineer
04-02-2012, 05:08 PM
This sounds like a very good assessment of the situation, specifically regarding the amino groups. Not something I know much about, but definitely, the DT mechanism relies on a special relationship between certain types of dyes & gelatin protein.

And regarding, That is certainly my understanding as well. I've transferred magenta dye to a fixed-out (non-hardening) FB paper and the density is very good, but diffusion is terrible! The mechanism of imbibition though, relies on this pH gradient and not a mordant.

Speaking of which... you can buy thorium nitrate on eBay for fairly low prices. Not that I'm even considering such an endeavor..

Read the responses I posted and that Jim Browning posted.

PE

holmburgers
04-03-2012, 11:27 AM
I always read what has been posted by you two, and I didn't mean to gloss over it in my post. I do think, though, that it's the gelatin-to-gelatin transfer that should be considered the "fundamental" mechanism. To me it seems like the mordanting aspect is an improvement, not an embodiment of dye-imbibition itself, which can be demonstrated in the simplest form with a gelatin relief, dye and any absorbent surface.

So as far as Bill is concerned, the crux is whether PVA will act similarly to gelatin in its ability to absorb a dye solution, and that's what T-grain was addressing originally.

wildbillbugman
04-03-2012, 12:54 PM
Hello All,
Since I,prematurely at best, started this thread, I have read much speculation and no hard evidence. I should have done some experiments. Then either opened my big mouth,or not.
When I first started my goal of making a panchromatic emulsion, I got more discouragement than encouragement, to say the least. When I started using silane treated PVA instead of gelatin , the same. Fortuneately, I kept going anyway.
I am not saying that the reasons set fouth in this thread, for the inpractability of of what I asked about are not correct. They probably are correct. That is why I am puting this whole topic away, for now. And I have more promissing things that I can do with my time. If I ever decide to pursue anything having to do with dye transfer, I might well return to gelatin in order to work with what has already worked.
Bill

holmburgers
04-03-2012, 01:33 PM
At the risk of saying too much (which I'm wont to do), I'll simply add that regardless of the workability your proposal, the proposal itself has sparked a valuable discussion.

Sometimes the most interesting stuff comes about when people speak before they think, contrary to what countless elementary school teachers and mothers have always told us!

wildbillbugman
04-03-2012, 02:43 PM
Jack Denim as just posted a very relavent artical on Jim's Yahoo Forum "Dye Transfer.
Bill