Diazo-Sensitized Carbon Transfer

[keesbran]

Well the plan at present is to ship the big order to me, and I will package and ship everything out myself

Do you plan to repackage it from bulk? Then you will need UV blocking glass or plastic bottles and a black plastic bag per bottle.

Also did you ask Secant if they plan to continue selling the CAS 2718-90-3, diazidostilbene in the future? It looks they are selling out this batch at a special price. If they stop this will be a dead end...

Kees

 

[holmburgers]

That would likely be the plan; repackaging it from bulk. I've already started looking at amber PET bottles and that kind of thing. Doing it right will be my #1 priority.

Here's what Secant says about this sensitizer; they have about 60kg left that they are selling it for a small markup over cost. After this, they said they're not sure about how much another manufacturing run would cost, but it might be in the $1000/kg range. That's still cheaper than say, Sigma-Aldrich or TCI. And there might be more of this stock elsewhere in the world(?). However, they basically don't know (or haven't said) what a mfg run would cost and hope that they can get their manufacturer to do it "reasonably."

What's important now, in my eyes, is to get to know this stuff and develop as much knowledge about it as we can. 60kg is a lot, and this group buy will put more of this sensitizer in the hands of at-home-carbon-printers than ever before.

 

[keesbran]

Doing it right will be my #1 priority.

Excellent, I had no doubts about that! My own provision from another supplier was packed in a brown glass bottle within a black plastic bag. Same kind of bag as we know from photopapers. Brown glass or brown PET probably doesn't block enough UV. Dick Sullivan somewhere mentioned special UV blocking bottles he used. Not brown but opaque white.
The powder itself is light sensitive so all handling should be done with safe light.

60kg is a lot, and this group buy will put more of this sensitizer in the hands of at-home-carbon-printers than ever before.

Yes, and after that we probably have to go to China for more.... I'm still interested to know about Secant's Eastern European manufactures.

About quantities:

Carbon tissue with diazidostilbene incorporated needs a gelatin/diazidostilbene ratio of 0.04 - 0,06. The 0.06 ratio equals the behaviour and printing time of 3% dichromate sensitized tissue. With a lower ratio contrast gets higher, sensitivity lower, nothing new.
So for every liter of 10% glop you need 4 to 6 grams diazidostilbene. With a kilo one can make 166 to 250 litre of glop. This coats 237 - 357 square meter tissue with a 0,7 mm wet height. A square meter can be cut down to twenty 8x10inch tissues. A kilo is good for at least 4740 8x10 prints. One has to have a serious production workflow!

-k

 

[keesbran]

clearing

Another remark about clearing:

I have been doing mostly double transfer, where clearing is not a big problem as the image is transfered to a polyester support and seems to wash much better. This is different with single transfer to a paper. Yellow stain in the paper is visible when the print is dry. When the print is not properly washed as happened to my students last weekend it is even worse.

The original Ultrastable method used a white polyester base sheet for the final print. Apart from easier registration, clearing might be one of the reasons for using polyester for single transfer.

I could clear the single transfer prints on paper with the normal permanganate/ sulfite-metabisulfite method, but they had to stay much longer in the sulfite bath. On one print a little yellow tone in the paperwhite is still visible.

So if you only do single transfer this might be an issue. Maybe there are other efficient clearing agents though.
By the way: I kind of like double transfer now. Not that difficult to start with and very easy once used to it.

-k

 

[gmikol]

I had a chance to meet Tod Gangler yesterday at Alt-Photo Pacifica, and pick his brain a bit. I found him to be quite generous with his time and knowledge.

I learned a few things from him that I'll be writing up the next couple of days. Coincidentally, on the Yahoo carbon list, Sandy King had asked about how light sensitive this process was with regards to handling both the raw sensitizer and the finished tissues. Since I have that written up already, I thought I'd share that first.

Apologies if you've already seen this on the Yahoo list.


The sensitizer is most sensitive as a dry powder, decreases as its put into
solution and added to the emulsion, and is even less sensitive in the dried
tissue.

Tod's recommendations for maximum light levels were thus:
-- Red safelight only for weighing the powder and adding it to solution.
-- Safelight + very dim 60W tungsten (as low a setting on a dimmer as
possible to get it to light) for adding to the emulsion.
-- A 60W bulb mid-way on a dimmer for pouring the emulsion. He uses a slightly
lower level for black and yellow, since his pigments are more prone stain, so
minimizing fog is first-priority. Slightly higher levels for cyan and magenta
because they are less prone to stain. This may vary depending on the exact
pigments that one might use.


I'll add this from my own experience: Pouring tissues onto clear substrate in red safelight conditions is frustrating if you're not using some sort of frame. Pouring onto a yupo-type material, as Tod does, might be easier because it's easier to see the edges of the substrate. I've taken to outlining the tissues (which are squeegeed onto glass) with a silver sharpie. Much easier to see the edges that way. I may consider switching to a Yupo-type material, much as I like using the Dura-Lar.

--Greg

 

[gmikol]

I have been doing mostly double transfer

Kees...

What are you using for your temporary support?

--Greg

 

[keesbran]

Kees...

What are you using for your temporary support?

--Greg

I'm using Yupo 160/200gr

-kees

 

[gmikol]

Thanks for the reply...I always thought the gelatin bonded to Yupo too strongly, and it was only appropriate for tissue or final support.

Do you treat it in any way to get the image to transfer cleanly to your final support?

--Greg

 

[keesbran]

Thanks for the reply...I always thought the gelatin bonded to Yupo too strongly, and it was only appropriate for tissue or final support.

Do you treat it in any way to get the image to transfer cleanly to your final support?

--Greg

No, i never had any problems with yupo. When I first I started to use it I cleaned it with dish washing soap and rinsed it. Nowadays I only rinse it before use. The wet sheets are squeegeed to a large leveled plate of glass. Then I remove all water but try to keep the surface somewhat damp, not wet, before coating with a #200 rod. Smaller formats I coat either within a frame of magnetic strips or directly on the yupo whitout frame. Then I use a comb to spread. I hate to clean and dry the magnetic strips each time inbetween! That's why I coat whitout strips also, which is very time saving and my preferred method for small sizes now, I use sheets of Yupo about 2,5 cm/ 1 inch bigger on all sides and mark the area where I want to coat. With some practice I'm able to coat nice straight squares now. I coat 8 sheets in one batch, let them dry flat for some time, and hang them to dry verticaly.

I am also reusing the yupo sheets. That's why I use the 160 and 200gr sheets. First I used a thinner one that comes off somewhat easier in the warm water but is much more difficult to handle before that. For color prints I use the 200gr. Registration holes can be punched in directly.

 

[gmikol]

Kees...I appreciate your detailed response regarding how you make your tissues. For those of us in the US, I believe the 200 gsm weight of Yupo is equivalent to the 74 lb. Yupo.

I think there was a misunderstanding at the root of my question, however.

You said you do double-transfer for your color work. I was asking about the temporary support...the material you transfer each color layer to before you transfer the whole assembly to the final print paper.

Sorry about the confusion...

--Greg

 

[keesbran]

Kees...I appreciate your detailed response regarding how you make your tissues. For those of us in the US, I believe the 200 gsm weight of Yupo is equivalent to the 74 lb. Yupo.

I think there was a misunderstanding at the root of my question, however.

You said you do double-transfer for your color work. I was asking about the temporary support...the material you transfer each color layer to before you transfer the whole assembly to the final print paper.

Sorry about the confusion...

--Greg

Sorry, I misread your original question indeed! I have tried many temporary supports, also with my dichromates workflow. I had succes with transparant sheets of PVC/vinyl from one supplier, but not from another. Also the polyester sheets I found did not work very well at that time. Lots of frilling and other transfer problems.

This changed dramaticly when I tried the albumen method. Tod's video shows how to do it and a write up of his method can be found at the sizing appendix of Dick Sullivan's Carbon Printing Manual. It really makes transfer very very easy! A description of the same method by Gary Baker can be found in the Yahoo Carbon list Dead Link Removed.
But it reintroduces dichromates again..., although in very low concentration. So next I will try to harden it with DAS (from Di-Azido-Stilbene, the chemical industries nickname for our beloved powder) as suggested earlier by Charles. With an albumen coating you can use almost any transparant substrate. For the moment I prefer transparant polycarbonate (0,25mm). It is very dimensionally stable and stays perfectly flat.

By the way: for the sake of continuity I did some reseach for other diazidostilbene suppliers worldwide. I found a Shanghai based chemical company that sells 1 kg for $350 - not a bad price! It's double the price from the current Secant sale, but they seem to have it in generous quantities!

 

[Photo Engineer]

Just FYI, Yupo is very similar to Ultrastable. These supports are very similar to the support used for coating Ciba/Ilfochrome color material.

PE

 

[CMB]

Just FYI, Yupo is very similar to Ultrastable. These supports are very similar to the support used for coating Ciba/Ilfochrome color material.

PE

This is not correct.


The base material used for coating Ciba/Ilfochrome was Melinex, manufactured by ICI , is Polyester . Yupo is made of polypropylene and is similar to the Kimdura "synthetic, water proof paper" that was used as a base for coating the UltraStale pigment films.


Polyproplyene should not be used as the final support for carbon transfer prints. Testing has shown it exhibits serious long-term adhesion and cohesion failures.


The white UltraStable base had a gelatin top coat over an in-line gel subbing layer. A receiving top coat is necessary for the long term stability of any prints made onto polyester.


A rule of thumb: if you can transfer the image from a temporary support sheet (yupo, polyester, etc). it should not be used as a final support. You can also test for this by using scotch tape to peel off the processed gelatin image.

 

[Photo Engineer]

I did NOT say they were identical. I said they were similar, ie, they are plastic like, subbed white reflective materials. They all resist processing solutions and all will accept gelatin coatings provided the subbing is correct.

Melinex is a transparent material in most all incarnations I have seen, and the version used must be chosen with the application in mind as it does not always work out right, just as Polypropylene is not always right. Since one of the people here uses Yupo, it must be that he has found a way to work with it in carbon printing, but IDK. His post suggests that it works just fine.

PE

 

[CMB]

Sorry about the miscommunication. To clarify:


Melinex 990, an opaque white polyester, was used as the base for Ciba/Ilfochrome (7 mil) and some UltraStable (9 mil) prints. The clear polyester did contain a small amount of transparent white pigment (TiO2) but was extruded in such a way that "soap like bubbles" were formed that reflected, rather than transmitted, visible light thus causing the clear polyester sheet to appear "white".


Another feature of the 990 was the "Bexford Sub' - a thin layer of gelatin applied "in-line" (as the polyester was being made) at ICI's Bexford plant. This subbing layer was designed to receive and anchor subsequent coated layers to the polyester support.


As you know, gelatin stress increases with film thickness, and high relief carbon prints are particularly susceptible to cracking and base lift-off. After the Bexford plant blew up in the late 1990's the in-line gel sub was no longer available, other subbing techniques (corona discharge, chemical etch, off-line gel layer, etc) were tested but all showed signs of adhesion failure and UltraStable discontinued offering a White base. The adhesion performance of these new sub subbing layers, however, were suitable for Ilforchrome

Charles

 

[Photo Engineer]

Charles;

Thanks for the clarification.

I have about 50 feet of full width Ultrastable here as well as several pads of Yupo. See above for others using Yupo. It seems to be ok. As for coating on Estar / Melenex type films, Kodak coated regularly on ~4 mil, 5 mil and 7 mil Estar using corona treatment.

PE

 

[gmikol]

Tod Gangler on pigments

I've had a chance to organize the last of my notes from my conversation with Tod Gangler last weekend, and supplemented with some findings of my own.

We talked about pigments a bit, and he introduced me to a concept known as "pigment shock". This was a new term to me, but apparently well known in the paints and industrial coatings universe. In doing a little digging on the 'net later, I found out that when introducing a pigment in suspension into a vehicle (in this case, our vehicle is melted gelatin), various interactions between the temperature of the 2 components, and physical interactions of the solvents/binders/etc. in each case can cause the pigment particles to flocculate, causing an increase in particle size (which also means a reduction in tinting strength) and a tendency to stain, due to larger particles being more likely to fall out of suspension.

For this reason, Tod recommends pigments in aqueous suspension (as opposed to watercolor tubes), and further recommends that the aqueous suspension be further diluted with water, (I assume to both reduce viscosity and concentration), and brought up to the temperature of the gelatin before incorporating.

With further regard to pigments, he noted that one of the pigment suppliers (manufacturers) he has used in the past has gone out of business, and he is not sure he could order in the same (relatively) small quantities from 2 others. For newcomers interested in color carbon, he recommended the Kremer color concentrates. The pigments which he uses were no surprise: pthalo blue green shade, quinacridone magenta, and one of a few different yellows, bismuth vanadate, permanent (benzimida) yellow, and isoindolinone yellow.

My note: as near as I can tell, these would be PB15:3, PR122, PY184, PY154 (possibly PY151) and PY109. I'm guessing that the isoindolinone is PY109, the green shade, as opposed to PY110, the red shade. Handprint.com does not address PY109, and it's not one I've seen in previous discussions about tricolor pigments.



I hope this info helps somebody out there...

--Greg

 

[keesbran]

For this reason, Tod recommends pigments in aqueous suspension (as opposed to watercolor tubes), and further recommends that the aqueous suspension be further diluted with water, (I assume to both reduce viscosity and concentration), and brought up to the temperature of the gelatin before incorporating.
--Greg

Thanks Greg! Tod's information is very precise as allways, and is in line with my findings. I'm also using the Kremer concentrates (see (there was a url link here which no longer exists) for direct links). For monochrome work I sometimes work with bulk archival inkjet inks. Especially one carbon black, Epson Ultrachrome replacement ink, sold by MIS as Eboni black. It actually comes from Image Specialists (WJ1082). I never tried full CMYK carbon with inkjet inks but that should work. I allways felt using inkjet inks was a bit cheating... At least colours are nicely balanced out of the bottle.

Inkjet inks are very finely divided and kept in suspension by some extra's, mainly glycol. I never saw any side effects from these extra chemicals. The Kremer pigments concentrates contain also dispersion agents and differ quit a bit how the keep in suspension in their bottle. The bismuth vanadate yellow is the most difficult to keep in suspension. The other 3 colors not. Finding the right colorbalance is also somewhat difficult! I am using these several years for tri-color gum, so I knew them allready. As a rule of thumb one needs equal parts (in weight) of the K (1 part) and C (1 part), a little less M (0.8 part), and a lot more of the bismuth Y (1.6 part).

Regarding the colorconcentrates: I allways dilute the pigment with water and bring this to temperature before mixing. The mixed glop I keep for at least one hour on a temperature controlled magnetic stirrer with the temperature sensor in the mix. The also warm DAS (3% in water premixed) goes in at this last stage. be careful to use safelight from that moment. I count for this extra water added when making the gelatin mix.

The Kremer isoindolinone yellow (PY109) can be found here and the Permanent Yellow (PY154) here.

-k

 

[holmburgers]

Awesome discussion; you guys are seriously getting down to brass tacks.

Just a quick update from me: haven't heard from Secant for a couple weeks, and I've sent a note to Tod to see if he received the sample. If not, I need to get on the phone to Secant. Hopefully it's just a lapse in communication, nothing more.

So far, 11 kilograms is spoken for, and there are a handful of people on the list who haven't provided me with quantities; so that number is likely to rise a fair bit.

OVER and OUT

 

[Orioes]

Diazo-Carbro

Does anyone know if Diazidostilbene would work in the Carbro process? I'm interested in experimenting with carbon/bro and related processes in general but carbro in particular draws my interest. Relatedly does anyone have a description of the chemical process that underlies carbon/bro. I've been looking around for one but most I've seen are more a description of how to produce a print then the underlying chemistry.

 

[gmikol]

Chemically speaking, carbro and carbon are very different. Carbon transfer is an ultraviolet light sensitive process. The UV light reacts with a traditional sensitizer (potassium or ammonium dichromate), or with a "modern" sensitizer like we're discussing here, causes the gelatin to harden in proportion to how much light it received in order to trap pigment in the gelatin. You wash off the remainder in hot water, and are left with an image.

Carbro is a purely chemical process. It uses a very different sensitizer, which, when the sensitized carbon tissue is brought into contact with a conventional silver gelatin print, reacts with the silver and causes the gelatin in the carbon tissue to harden. The more silver (darker areas on the print), the more hardening of the carbon tissue.

There it is in one paragraph each.

William Crawford, "The Keepers of Light"
Richard Farber, "Historic Photographic Processes"
Sandy King, "The Book of Carbon and Carbro"

These 3 all have decent descriptions of the similarities and differences between the 2 processes. The first 2 are out of print, AFAIK, and the 3rd is self-published. Some google searching might yield some hits, too.

To others on this thread...I don't own any of Nadeau's books. Does he address carbro at all?

Hope that helps...

--Greg

 

[Orioes]

Chemically speaking, carbro and carbon are very different. Carbon transfer is an ultraviolet light sensitive process. The UV light reacts with a traditional sensitizer (potassium or ammonium dichromate), or with a "modern" sensitizer like we're discussing here, causes the gelatin to harden in proportion to how much light it received in order to trap pigment in the gelatin. You wash off the remainder in hot water, and are left with an image.

Carbro is a purely chemical process. It uses a very different sensitizer, which, when the sensitized carbon tissue is brought into contact with a conventional silver gelatin print, reacts with the silver and causes the gelatin in the carbon tissue to harden. The more silver (darker areas on the print), the more hardening of the carbon tissue.

Ah! this explains my confusion. While I was aware of much of what you wrote I for some reason had it in my mind that carbro used the same dichromate sensitizers + non-supercoated bromide paper + some special bleach to achieve the chemical hardening. I must have conflated carbro and ciba for some reason.

Edit: Speaking of pigments earlier, has anyone studied whether color carbons benefit from using more then the standard CMYK colors? I'm thinking of things like Hexachrome, CcMmYK, or PMS that use additional colors to improve color reproduction among other things. In theory you could also add interesting special effects. Take a normal light and UV photograph of a flower and use normal and UV fluorescing pigmented tissues so that under normal light it displays as the normal light photograph and under UV as the UV.

 

[CMB]

Does anyone know if Diazidostilbene would work in the Carbro process?

Good question. Dichromate is one of the chemical components of the carbro bleach. Whether or not DAS can be used in those formulations in place of dichromate, AFIK, has not been tried. My guess is that because gelatin does not spontaneously harden (cross-link) in the presence of DAS as it does with Dichromate, the answer is, probably not. A chemist could tell you why.

Charles

 

[keesbran]

The Chinese Envoy was here!

Yesterday I received some DAS directly from Shanghai. Tested it today.
It's somewhat more light sensitive than my previous locally bought provision. And a very fresh batch.

-kees

 

[Bob Carnie]

I can make separation bromide prints on fibre or rc black and white paper> if anyone here wants to try to work out a Carbro workflow I will collaborate and supply the separated silver prints.
This is not a direction I am currently exploring but since I make silver gelatin positive prints as a matter of course, making negative bromides are very easy for me to do.
I have a ton of out dated rc paper black white which may work just fine.

If anyone is interested and wanting to work in collaboration over the winter on tri colour carbro send me a email bob@elevatordigital.ca , I am set up to be able to work with more than one worker if there is interest.

Chemically speaking, carbro and carbon are very different. Carbon transfer is an ultraviolet light sensitive process. The UV light reacts with a traditional sensitizer (potassium or ammonium dichromate), or with a "modern" sensitizer like we're discussing here, causes the gelatin to harden in proportion to how much light it received in order to trap pigment in the gelatin. You wash off the remainder in hot water, and are left with an image.

Carbro is a purely chemical process. It uses a very different sensitizer, which, when the sensitized carbon tissue is brought into contact with a conventional silver gelatin print, reacts with the silver and causes the gelatin in the carbon tissue to harden. The more silver (darker areas on the print), the more hardening of the carbon tissue.

There it is in one paragraph each.

William Crawford, "The Keepers of Light"
Richard Farber, "Historic Photographic Processes"
Sandy King, "The Book of Carbon and Carbro"

These 3 all have decent descriptions of the similarities and differences between the 2 processes. The first 2 are out of print, AFAIK, and the 3rd is self-published. Some google searching might yield some hits, too.

To others on this thread...I don't own any of Nadeau's books. Does he address carbro at all?

Hope that helps...

--Greg