Diazo-Sensitized Carbon Transfer

The thing I dislike the most about carbon printing is sensitization. Issues of waste dichromate disposal, waiting for the tissues to dry after sensitization...I find it tedious, especially for a "hobby" printer. In a more production-oriented environment, sensitizing, exposure, mating, development can all be batched or pipelined to some extent, but I'm not there. And I don't have the possibility of storing sensitized tissues in my freezer.

So I'm intrigued by the possibility of a diazo-sensitized tissue that is stable on the order of weeks (or even more, perhaps), so that I can just make one print (relatively) quickly, when I have a chance. In poking around some dark corners of the internet, I came across an anecdotal report of someone using a screenprinting diazo sensitizer with gelatin. (This was to make dye-transfer matrices, but the principle is the same).

Dead Link Removed

Not being able to track down the specific emulsion the poster wrote about (Nazdar 101), I used one that was available at my local art store, the Speedball emulsion sensitizer, reasoning, as the OP did, that most of the screenprinting emulsions are probably similar.

Well, I did this, and mixed up a small batch of glop, to which I added the sensitizer. I noticed that the consistency of the glop was different as I was pouring it. A bit thicker, and a little "gummy". Dried for about 44 hours in black or red-safelight conditions.

The poured tissues were completely insoluble. So something went wrong...now I just have to figure out what.

I have a couple of thoughts, and I'd be curious what the collected wisdom thought...

1) The diazo sensitizer used is completely incompatible with gelatin. Not much I can do there except try and find a different option.

2) The sensitizer I used is not stable enough, and broke down over the 2-day drying period of the tissues, hardening the gelatin.

3) I added way too much sensitizer. Despite using roughly the same proportions as the message I referenced above, the chemicals were sufficiently different so as to make the amount I added a gross excess, which contributed to the hardening.

4) Despite the MSDS identifying only the diazo dye and some phosphoric acid (which I assumed would not affect the gelatin in the quantities used), perhaps there was some other substance in the dye solution that caused the hardening.

5) The high temperature of the glop solution (115 F) caused the sensitizer to break down and harden the gelatin.

I'd love to explore the possibilities of this more, but I don't know where to go from here. Any help regarding sensitizer sources (or particular commercially-available compounds to look for), methods, etc. would be greatly appreciated.

--Greg

The info you are seeking can be found in Kosar, Light Sensitive Systems, Wiley,1965. Although he devotes a whole chapter to Diazotype Processes, you will probably find his discussion of Aromatic Azido Compounds starting on page 330 the most useful. Allow me to quote:

"In combination with gelatin, glue, gum arabic, etc. aromatic azide compounds were suggested for about the same processes as previously described dichromates…"

Add to this: non-toxic, no dark reaction, and capable of long term storage after sensitization.

This is what was/is used as the UltraStable sensitizer.

Thank you, Charles, for the reference. Much as I had been looking for a concise, practical answer, I realize that I know little to nothing about the chemistry at play here (my background is in micro-electronics), and so a little education is definitely in order.

Turns out Powell's Books here in Portland had a nice, affordable copy on the shelf, just waiting for me. Now I just have to find an excuse to go downtown and pick it up...

CMB said:

Add to this: non-toxic, no dark reaction, and capable of long term storage after sensitization.

Click to expand...

I always thought the last 2 were intrinsic to this family of compounds. I guess not.


While you've previously identified the UltraStable sensitizer, I'd also like to find compounds that may be more readily available, and perhaps less expensive ($54 for 10 grams from the one source I was able to find online) than that, though I certainly don't know how far 10g would take me.

--Greg

Greg, it's awesome that you're taking this work upon yourself. Aside from UltraStable, is there anyone out there using diazo sensitizers for carbon?

I actually corresponded with that fella from the dye-transfer post you linked to (small world!); I'll dig up the email and see if he gave any tips.

Out of curiousity, what was your tissue support & pigment?

update: How much sensitizer did you use? The DT-Yahoo! post says 4mL per 100mL, but in our personal corerspondance he says "250ml water, 15 ml gelatine, with sugar (amount appears to depend on humidity), and six drops of speed ball sensitizer". Perhaps you're adding too much?

So my recipe was my standard high-relief tissue, and it was a small batch.

14g Gelatin
125 mL Water
4mL Glycerin
0.8g M.Graham Lampblack Watercolor
10mL Isopropyl Alcohol

I pour onto Dura-Lar clear 0.005" film.

The OP had said that 4mL for an 8% gel solution was pretty high contrast. Since I'm using more gelatin, and wanted a lower contrast, I used 10mL for that batch. 6 drops is waaaaaayyy different than 10mL (using the old rule of thumb that 20 drops = 1 mL)

In doing some digging around, I've discovered something. The other manufacturers he mentions (Kiwo, Ulano, Nazdar), all use the same sensitizer, Diphenylamine-4-diazo sulfate CAS # 41432-19-3. So perhaps the 4mL / 100mL (8% gel) is appropriate for these.

Speedball uses something different: Polymethylene-p-Diazo Benzene Dye CAS #71550-45-3.

As far as I can tell, Speedball is the only one that is still available separately (without having to buy and then discard the screen emulsion).

I won't get a chance to try anything else until after the 4th. But if we continue to have a cool summer, I can make some other tests. If it warms up, then it gets too warm for me to pour tissues (no A/C), and it will have to wait 'til fall.

--Greg

Looking at MSDS sheets it seems some screen printing sensitisers have formalin in them, which would explain insoluble tissue.

But screen printing relies on the use of an emulsion as well, how does it not harden that?

That's a great lead though.

mdm said:

Looking at MSDS sheets it seems some screen printing sensitisers have formalin in them, which would explain insoluble tissue.

Click to expand...

Yep...I saw those data sheets. That is not the sensitizer I used, so that can't be the exact problem that I had. But I saw one datasheet that listed the chemical in question as:

Chemical name DiazoniumSalt: p-diazodiphenylamine sulfate, formaldehyde condensate (41432-19-3).
Note: End product does not contain free formaldehyde.

Click to expand...

Emphasis mine.

In the thread from the dye transfer list that I linked to, the OP claims to have tested (successfully) a number of different manufacturer's sensitizers, some of which use the chemical above. I plan on testing it if I can get my hands on it (without having to also purchase the screen emulsion along with it.)

--Greg

I was told by a collaborator that in Bob Pace's "Keeping Pace" newsletter there is something about a diazo-sensitized emulsion of Mssr. Berger's that worked well for imbibition.

I'm gonna try to get a hold of that; Charles, do you happen to have a copy of that easily available?

Check out the "Keeping Pace" newsletters from 1994-1996. I had first shown Bob some dye transfer prints made by Girard Aniere in 1994 using UltraStable films (the same ones you have) to form the matrices. Although the enlarged separations were made with a 400lpi screen, the print appears to be continuous tone (even when viewed with a high power magnifier) because of the diffusion of the dyes. I've uncovered some correspondence with Bob in 1996 also discussing this approach to making dye-transfer prints but I can't refer you to any specific issue of his newsletter that covers this topic.

BTW : Bob Pace, in 1997, published his book Making Enlarged Separation Negatives for the UltraStable Process, which may be of interest to those who wish to use con-tone negatives to produce color carbon prints.

The Keeping Pace newsletters can be found by googling "Making Enlarged Separation Negatives for the Ultra Stable Process" the first 2 links.
google "http://www.daviddoubley.com/Documents/KeepingPaceNewsletters/" for lots of them. They dont seem to be accesable directly from his site.

Seems most all Kiwo sensitisers contain formaldhyde but the % varies. Dead Link Removed
Seems Ulano 925WR sensitiser contains formaldehyde. Unshure about Ulano RLX emulsion sensitiser but it costs $200 for a gallon of the stuff and I am not going to risk $200.
After reading the post on dye transfer group I have decided to try the sensitiser that comes with Kiwo 225WR as it is available in small quantities locally.

Printing without Dichromate would be good for my health and the environment. Diazo is much easier to get than Dichromate. Also presensitised tissue would speed up printing dramatically, the disadvantage being in controlling contrast but with digital negatives that is not a problem.

I still don't have anything definitive as to whether these formaldehyde condensate sensitizers are appropriate or not, but I think you are misreading that MSDS that you linked to. The composition is 89-99% of CAS #41432-19-3, and 1-11% of "Sodium salts", there's no suggestion of any free formaldehyde in this sensitzer, as I'm reading it.

I really hope to find sources for these sensitizer compounds separate from the emulsions. It seems both cost- and resource-inefficient to have to purchase and then discard the emulsion.

2 more questions for mdm:

-- Can you buy just the sensitizer for Kiwo 225WR, or do you plan on discarding the emulsion?
-- Do you have a link to the MSDS for the sensitizer (Kiwo Sensitizer #14)? I'm curious to see whether it is the same as the ones (#1-#11) covered by the linked MSDS.

--Greg

I have to discard the emulsion. I will try it and see.

Maybe you can find a local scource for Nazdar 101 like the gentleman on dye transfer. There is a list of distributors on the nazdar website. http://nazdar.com/distribution.asp

Thanks for the David Doubley link... I've been to that website but didn't realize the quantity of excellent data there.

On the topic of sensitizer.. I'm not much of a chemist, but a chemist friend referred to the UltraStable sensitizer as Diazidostilbene Sulfonate. Is this just another word for the same stuff, or what exactly?

Perhaps a better method would be too look for a source for the raw chemical. I wonder if there are any DIY screen-printers or print-shops out there that make their own from scratch? IDK... but it's worth a shot.

If I wasn't swimming in projects to do, I'd dive in this with you guys. Has anyone checked out "Kosar, Light Sensitive Systems, Wiley, 1965" yet? Perhaps I'll sojurn to la biblioteca...

Ohh, also, I'd recommend that someone email Greg W. (dye-transfer OP) about this. He's a nice guy and would love to know that people are interested in this, I suspect.

This sounds familiar, essentially presensitised carbon tissue, just not the correct colours.
Dead Link Removed

holmburgers said:

THas anyone checked out "Kosar, Light Sensitive Systems, Wiley, 1965" yet?

Click to expand...

I picked up a copy before the holiday, and skimmed the section that CMB referenced. It's a bit over my head, chemistry-wise. I'll have to go through it again to see if I can glean anything useful from it.

I'm hoping Charles or someone else following this thread can answer the following question for me:

In looking through one chemical supplier's catalog, I came across a number of very similarly named compounds. It's not clear to me how they differ from one another as a practical matter, what benefits/detriments the different variations have, nor how to determine which would be appropriate for this endeavor. Example:

4-DIAZODIPHENYLAMINE/FORMALDEHYDE CONDENSATE HYDROGEN SULFATE
4-DIAZODIPHENYLAMINE/FORMALDEHYDE CONDENSATE HEXAFLUOROPHOSPHATE
4-DIAZODIPHENYLAMINE SULFATE
4-DIAZODIPHENYLAMINE/FORMALDEHYDE CONDENSATE HYDROGEN SULFATE ZINC CHLORIDE COMPLEX

The first one has the same CAS# (41432-19-3) as a widely-used screen emulsion sensitizer.

--Greg

mdm said:

This sounds familiar, essentially presensitised carbon tissue, just not the correct colours.
Dead Link Removed

Click to expand...

Not quite...

The developer used for these films is a 2-part powder (hydrogen peroxide can be substituted for the developer). The page also refers to these films as being "iron-salt sensitized". This makes it sound more like the Chiba System than traditional carbon transfer.

--Greg

I've just poured 2 rather imperfect 8x10 tissues made with different concentrations of diazo and should print with them in about 24 hours. I have stopped putting alcohol in my glop since I started coating with a rod and magnet wall, but had to do the 2 small ones with a comb in near darkness (not taking any chances), bubbles! Thats ok, they are destined for step wedges.

I dont see any reason why one could'nt brush sensitise dry tissue. May give that a try sometime too, though it comes with a time cost.

The 3rd chem on the list above looks good and it seems to be available from China at $28/kg (100kg minimum!) Also known as Diazo S or 4477-28-5 the difference of which is 4444, a good sign.

mdm said:

I dont see any reason why one could'nt brush sensitise dry tissue. May give that a try sometime too, though it comes with a time cost.

Click to expand...

I hadn't even considered this aspect of things. I would guess it would work. My line of investigation come from looking for a sensitizer-incorporated tissue, because I wanted to avoid the time cost associated with sensitizing and waiting for the tissue to dry.

If you do try brush-sensitize, please let us know how it works. Also, I've come across some references to diazo compounds that are soluble in alcohol (or maybe acetone), which would not be appropriate for a sensitizer-incorporated tissue, but could be appropriate for spirit sensitizing.

--Greg

Well, I can confirm that it works fine.

I got 1 quart of kiwicol 225 emulsion which came with 7.6g sensitiser. Surmised that the poster in dyetansfer would have used sensitiser for 1 gal so extrapolated that and diluted mine with 22ml luke warm water. I used 2ml/50ml glop for an 8x10 tissue. 12g/l pigment, 60g/l sugur, 70g/l gelatine.

Used 1/2 my usual exposure and have a good 10 steps on a 21 step stoufer, obviously underexposed with no good black. It looks very much like 4 or 5% Ammonium Dichromate to me.

The catch, it stains everything that comes in contact with the tissue a strong yellow.

At this stage it is very expensive printing, but if it can be had seperate from emulsion and provided it clears ok, its the way to go.

David

PS the stain seems to be a charachteristic of RC paper, it does not stain much when you transfer to the back, or maybe I didnt mix it enough when I poured. In the Todd Gangler video it is a double transfer, the first transfer to albumen sized melinex or something like melinex, therefor stain is less of a problem. Where did I read how to clear it?
It is not as sensitive as AD, 3rd transfer=20 min exposure (still going), 1st was 3 1/2 min for 10 steps, 2nd was 9 min for 13 steps, no black. I have another tissue sensitised at double the rate to try.

20minutes is coming close to a good black, 15 steps. My normal exposure with digital negs and 2%AD is 9min, that would be contrastier than this diazo.

Ok, this is a quote from the ultrastable thread to keep it all in one place for me.
"6. Clearing

When all four colors have been processed and fully dried, residual
chemicals are removed by immersing the print in Clearing Bath A for
1 minute, followed by a brief cold water rinse and then placed in
Clearing Bath B for an additional minute. After a final rinse, the
print is dried and ready for finishing.

Stock Clearing Bath A:
Water (at 110 F) 930 ml
Potassium Permanganate 6 g
Sodium Chloride (Table Salt) 14 g

Stock Clearing Bath B:
Water (at 110 F) 940 ml
Sodium (Meta)Bisulfite 30 g
Sodium Sulfite 30 g

To make working solutions of A and B, dilute each in cold water at 1:20."
All of this is easy to get and the only thing I dont have are condes crystals

This is definately workable for colour and multiple transfer, not sure that the dmax is there even with stronger sensitiser strength.

mdm, that's great. Perhaps once you get a result you're pleased with you could post a scan and start a new thread that doesn't say "= Failure"; though I guess anybody really interested would probably get past that title and read on. At any rate, awesome.

If I recall the UltraStable instructions correctly, the melinex in CMB's Tod Gangler video is plain, uncoated. That is what allows it to act so well as a temporary support. If that's the case, people sure are wasting a lot of effort in making "temporary supports" when just plan melinex will do.

update: Yeah, the only prepraration for the plastic sheet is:

The plastic sheet (typically 5-7mil clear polyester) should be washed
thoroughly with powdered soap (Comet) and a soft sponge before
use. This will give a slight “tooth” to the plastic which will help
pigment film adhesion. Cut the plastic sheet at least one inch larger
all-around than the final paper size.

gmikol said:

I picked up a copy before the holiday, and skimmed the section that CMB referenced. It's a bit over my head, chemistry-wise. I'll have to go through it again to see if I can glean anything useful from it.

I'm hoping Charles or someone else following this thread can answer the following question for me:

In looking through one chemical supplier's catalog, I came across a number of very similarly named compounds. It's not clear to me how they differ from one another as a practical matter, what benefits/detriments the different variations have, nor how to determine which would be appropriate for this endeavor. Example:

4-DIAZODIPHENYLAMINE/FORMALDEHYDE CONDENSATE HYDROGEN SULFATE
4-DIAZODIPHENYLAMINE/FORMALDEHYDE CONDENSATE HEXAFLUOROPHOSPHATE
4-DIAZODIPHENYLAMINE SULFATE
4-DIAZODIPHENYLAMINE/FORMALDEHYDE CONDENSATE HYDROGEN SULFATE ZINC CHLORIDE COMPLEX

The first one has the same CAS# (41432-19-3) as a widely-used screen emulsion sensitizer.

--Greg

Click to expand...

Items 1 and 2 above are the Sulfuric Acid and Fluoro-Phosphate salts of the basic diazo material. Both are condensed with formalin and if it is released, it will harden gelatin. Decomposition of the Diazonium salt in an image forming configuration will harden the gelatin imagewise. Premature release will cause overall hardening.

Three above is the Diazo salt of Sulfuric Acid with no Formaldehyde. It will not harden gelatin as there is nothing to release, but the Diazonium salt can react with amino groups in gelatin and have some effect.

I am not familiar with #4, but it looks to be similar to #1 and 2 with Zinc added. These additions help stabilize Diazonium salts which are not known for stability. They can be explosive and can release Nitrogen spontaneously and end up inactive or reactive in another fashion.

PE

Thanks for that response, PE. I think I understand (in principle) what you're saying, and it makes sense to me. Are these "formaldehyde condensate" compounds the only diazo compounds which are appropriate for this use? I understand that the UltraStable sensitizer (Diazidostilbene Sodium Sulfonate) is from a slightly different family of compounds, but it obviously works, as well.

--Greg

mdm said:

Used 1/2 my usual exposure and have a good 10 steps on a 21 step stoufer, obviously underexposed with no good black. It looks very much like 4 or 5% Ammonium Dichromate to me.

[...]

3rd transfer=20 min exposure (still going), 1st was 3 1/2 min for 10 steps, 2nd was 9 min for 13 steps, no black. I have another tissue sensitised at double the rate to try.

20minutes is coming close to a good black, 15 steps. My normal exposure with digital negs and 2%AD is 9min, that would be contrastier than this diazo.

Click to expand...

David--

I'm glad to hear that your first attempts worked out well for you.

What light source are you using?

--Greg

Greg:

I'm afraid that my knowledge off these systems is limited to a smattering of the chemistry. My copy of "Light Sensitive Systems" is back at EK where it belongs. Sorry.

PE