Diazo-Sensitized Carbon Transfer

[Photo Engineer]

And, I am working on a preservative to replace Thymol that is 40x more effective. If I can get the chemicals, I have one that is 40x more effective than that as well.

PE

 

[T-grain]

PE, did you consider the use of sodium benzoate? It should not interfere chemically (redox-wise), it is nicely soluble in water etc.

I have another question, a bit off-topic, but anyway-if I understand well, the incorporation of dichromate directly in the glop before coating (instead of putting the tissue to "swim" in it, thus handling loads of dichromate) is undesirable because there is the "dark" reaction (reduction) occurring in the coated tissue. BUT, there is sucrose as a plasticizer and thymol, both having some "nice" reducing properties, giving us the reduced Cr(III). IF we replace sucrose with sorbitol, thymol with, say benzoate (or something similar), the tissue with dichromate should be stable for a long time, provided it is kept away from UV light. Correct?
Is there anybody who tried this before (I am not into carbon, although intend to, someday...)?

 

[Photo Engineer]

Well, there are several answers here. Benzoate is too weak to stabilize gelatin against bug attacks except at high concentrations so I don't use it. It was used in the old color stabilizers but it made the film or paper tacky to the touch at the concentrations needed. Sorbitol does the same thing, rendering things tacky. Thymol is not a notable oxidant or reductant AFAIK.

You need a stabilizer (Bacteriostat) that works against gram negative and gram positive bacteria and also against molds and fungi. This can take 3 chemicals to do the job properly. And, the bacteriostat must not hurt the photographic process.

PE

 

[T-grain]

sodium azide (a bit poisonous, yes) ?

so there isn't a good replacement for sucrose? maybe inulin (polyfructane)? it doesn't have any reducing sugar unit.....

 

[Photo Engineer]

Sodium Azide is quite toxic. I will not use it. Phenol is very good, but now on a restricted list.

PE

 

[keesbran]

The "recipe" for the UltraStable pigment films is based on (except for the sensitizer) the formulation published in "The Home Manufacture of Materials for Carbon Printing" ( Wm. D. Fleming, American Photography, Vol 32, 1938, August, No. 8)

Thanks Charles!

 

[T-grain]

Sodium Azide is quite toxic. I will not use it. Phenol is very good, but now on a restricted list.

PE

but also phenol is not really benign.....
anyway, what do you think about those substances?
Benzalkonium_chloride
Polyaminopropyl_biguanide
Polyhexanide


what are the bactericides-fungicides in contemporary commercial (film/paper) emulsions?

 

[Photo Engineer]

T-grain;

Many companies today use Phenol in their emulsions. When you open a fresh bag of Ilford paper, the odor hits you right off. It is also used in the subbing on Baryta and RC papers IIRC. Kodak used several natural products in theirs, but now uses a complex mix of heterocyclic compounds that cannot be easily obtained without a special license.

The ones listed in your post 107 are not in common use. The last chemical on that list appears to be misspelled. Is that correct?

No bacteriostat is benign.

I am considering Chloramphenicol as a possible bacteriostat. It is cheap and can be made available. I have to test its photographic effects.

PE

 

[T-grain]

PE
I wasn't aware of the fact Ilford uses phenol-actually I haven't been using Ilford paper for over a decade......thanks for the info

polyhexanide is just an abbreviation for polyhexamethylene biguanide

 

[Photo Engineer]

Ahhh, PHMB. That may affect the emulsion. IDK, I have never tested it. Many guanadine derivatives are used as mordants in emulsions requiring polymeric quaternary salts, but some do fog emulsions.

PE

 

[holmburgers]

IF we replace sucrose with sorbitol, thymol with, say benzoate (or something similar), the tissue with dichromate should be stable for a long time, provided it is kept away from UV light. Correct?

I don't think there's any cause to believe this would be the case.

Now, do I have hard facts to back this up? No.. but people have been carbon printing for going on 2 centuries (minus 40 years let's say) and although there's always the possibility of new discovery, I'd say that this one has been hashed out over and over again. In the literature there is information regarding extension of the shelf-life of sensitized tissues, but nothing that could compare to diazo/azido sensitizers.

 

[T-grain]

PE, you refer to silver halide emulsions, I guess?
maybe with dichromate or diazo stuff it would be another story

BTW, how is going your work with mordanting the dye in your dye-destruction (cibachrome) emulsions? last time I followed your posts, you said you tried with aluminum salts

 

[Photo Engineer]

No salt I have used is a good mordant. I will have to move to quaternary salts to get the results I desire. I have one at the present time that I plan on trying and I have some other avenues to pursue. But, I have been busy and this is a difficult and off-topic (for me) piece of work. I have also not found a good cyan dye.

PE

 

[T-grain]

I don't think there's any cause to believe this would be the case.

Now, do I have hard facts to back this up? No.. but people have been carbon printing for going on 2 centuries (minus 40 years let's say) and although there's always the possibility of new discovery, I'd say that this one has been hashed out over and over again. In the literature there is information regarding extension of the shelf-life of sensitized tissues, but nothing that could compare to diazo/azido sensitizers.

Chris, you're probably right (I never did a dig-in into carbon literature), but diazo sensitizers are probably not the only factor influencing the shelf life of ultrastable material
as a chemist I can tell dichromate solutions are VERY stable when kept in the bottle (in the dark of course)- we used to use dichromate for spectrophotometer calibration
I do not have the redox potentials here at hand (they are also pH dependent), but I cannot exclude glucose from reducing dichromate ions

 

[T-grain]

No salt I have used is a good mordant. I will have to move to quaternary salts to get the results I desire. I have one at the present time that I plan on trying and I have some other avenues to pursue. But, I have been busy and this is a difficult and off-topic (for me) piece of work. I have also not found a good cyan dye.

PE

we have faith in you, PE

 

[holmburgers]

as a chemist I can tell dichromate solutions are VERY stable when kept in the bottle (in the dark of course)

That's a good point actually.

The key is keeping it away from oxidizers, right?, so any organic material? But that would preclude the use of gelatin also.

 

[Photo Engineer]

Dicrhomate is an oxidizer. You want to keep it away from reducing agents.

PE

 

[keesbran]

1. Add 1.5 g of Hardener #3 to 50 ml of water at 85F and QS to 60ml.

Charles,

Maybe a stupid question (from a non english reader) but what do you mean with 'QS to 60ml'?

Kees

 

[holmburgers]

Dicrhomate is an oxidizer. You want to keep it away from reducing agents.

PE

Just looked up "redox" reaction... I get it now!

 

[Barry S]

...what do you mean with 'QS to 60ml'?

Kees

Q.S. (quantity sufficient) means add solvent to bring the total volume to:

 

[keesbran]

wow

I have poured several A4 and two A2 size sheets with 750ml glop sensitized with this magic 'hardener #3' (di-Sodium-4,4'-diazido-stilbene-2,2'-disulfonate tetrahydrate) I received last week. In this glop I mixed a dilution of the powder as Charles wrote above. So in this 750ml is 4,5 gr diazo salt.

While waiting for them to dry I couldn't resist to do some tests.
I diluted another 3 grams of the diazostilbene in 100ml water. And with this I tried:

1. A gum print
I mixed the 3% diazo 1+1 with my regular 14 baumé pigmented gum and tried several exposure times. None where succesful. The gum allways ran off the sheet leaving a yellow stained image in the paperbase.

2. A PVA print
Same setup but now I took a 10% solution of pigmented Mowiol 4-88, a partially hydrolized PVA. This worked a little better. There was some hardening at very long exposure times and a trace of an image was left.

So far so good. Probably the concentration of the diazo must be higher to make this work, at the same time rendering it unusable by it's cost.

But then....

I took one of my 'normal' pigment sheets and brush sensitized it with the 3% diazo solution. I exposed it, dried it overnight (!) and processed it as a normal carbon print, transfered to a sheet of fixed glossy RC paper.

And...

It worked perpectly. Maybe the exposure time could have been a little bit longer, but it is pretty close to a normal printing time!

So I'm very happy with my investment in this powder!

I was allready used a to presensitized carbon because I used Halvor Bjørngård's Chiba method of ferric hardening. But that's more complicated because it is so sensitive to oxigen. I experimented with several temporary protective layers, other than the agar-agar Halvor describes.

More tests will follow.

Kees

-k

 

[holmburgers]

Exciting stuff! You guys are doing really noble experimentation and ensuring that the carbon process will continue well into the 21st century when dichromates are unobtainable (assuming here), not to mention providing a safer and perhaps more convenient method.

 

[BenjaminAustin]

Alt Gums

1. A gum print
I mixed the 3% diazo 1+1 with my regular 14 baumé pigmented gum and tried several exposure times. None where succesful. The gum allways ran off the sheet leaving a yellow stained image in the paperbase.

Hi There,

I'm reading this thread in the hope that I can find a non dichromate sensitizer to use in my Gum Printing practice.
Have you had a chance to muck around any further with that sensitizer on gum prints?

Do you know of anyone else who is specifically looking to de-dichromate their gum printing?

Thanks

B

 

[keesbran]

Hi Benjamin,

No not yet, but I will do soon. But as I said with the diazostilbene it might be getting rather expensive.

Do you know of anyone else who is specifically looking to de-dichromate their gum printing?

B

Yes, Halvor Bjørngård describes a non toxic approach in his Chiba thesis about using ferric salts for carbon and gum printing. You can download it here: The Chiba System

 

[BenjaminAustin]

Hi Keesbran,

Thanks for that article Very informative!
I'll have a go at some of those processes at some stage and post my results

One thing that was very useful in that pdf is the method he uses for affixing the paper to a substrate. (Gelatin on the paper, then glued down - releases in hot water. Genius!)

If you have any further luck using the diazo salts with the gum printing I'd love to hear...

Cheers

B