Group Purchase of Azide/Diazo Sensitizer - replacement for dichromate in carbon, etc.

[gmikol]

I did some math (there was a url link here which no longer exists).

In brief, I estimated 6 grams per liter of finished glop.

I also estimated about 50ml of glop per 9x12 inch tissue. So that's about 20 tissues per liter.

In principle, 100 grams could allow you to make 16 liters of glop.

16 liters of glop could allow you to make as much as 320 9x12 tissues.

Of course, these numbers are all reasonable estimates, and will vary depending on your specific recipe and method, but it's a reasonable guideline.

Chris was planning on closing the order some time tonight, so I suggest you send him an email soon.

Check out the end of the first post of (there was a url link here which no longer exists) for contact info.


Best of luck.

--Greg

 

[Orioes]

How small a batch is it practical to make? I was thinking of using my DAS initially in experimentation (New colloids, does carbro work with DAS etc.) for which I have no need of 20 or even 5 tissues of any particular mix until I know it works. I'd hate to be wasting large amounts of something this hard to acquire in excessively large batches of test glop.

 

[gmikol]

How small a batch is it practical to make? I was thinking of using my DAS initially in experimentation (New colloids, does carbro work with DAS etc.) for which I have no need of 20 or even 5 tissues of any particular mix until I know it works. I'd hate to be wasting large amounts of something this hard to acquire in excessively large batches of test glop.

You can make fairly small batches, but it is dependent on how accurately you can measure ingredients. Another alternative is to make a 3% (maximum) stock solution of DAS. Measuring out small quantities of liquid is easier than small quantities of powder, IMO.

A single 4x5 inch tissue would only require about 10-15 ml of gelatin solution, so maybe only 1-1.5 grams of dry gelatin. And maybe only 60 milligrams of DAS. 2 ml of a 3% solution of DAS is 60 milligrams of DAS. Think carefully about exactly how small of batches you need.

Another possibility is to not make sensitizer-incorporated tissue. Rather, make a traditional carbon tissue, and tray- or brush-sensitize the DAS onto the tissue, replicating the process one would use for dichromates. This way tests and samples of tissue that are no longer useful to you can be discarded with little cost (pigment and gelatin cost relatively little compared to DAS.) Just something to think about. If you've never carbon printed before, it will take a few tries to get a recipe nailed down.

Yet another alternative would be to use pre-made tissues (Bostick & Sullivan). Then you can get used to working with the DAS by tray- or brush-sensitizing without the additional complications of making tissue.

Lastly, DAS is very highly unlikely to work with traditional carbro recipes. Carbro relies on a completely different chemical reaction to harden gelatin than traditional carbon printing. In order to develop a carbro-like process with DAS, you would need find a chemical (or chemicals) that will react in proportion to the amount of silver in your bromide printer to break the azide groups in the DAS which would cause imagewise hardening of the gelatin. Certainly not impossible if you're skilled in chemistry. But it is extremely unlikely that the traditional carbro recipes will work.

Best of luck...

--Greg

 

[mat4226]

You can make fairly small batches, but it is dependent on how accurately you can measure ingredients. Another alternative is to make a 3% (maximum) stock solution of DAS. Measuring out small quantities of liquid is easier than small quantities of powder, IMO.

A single 4x5 inch tissue would only require about 10-15 ml of gelatin solution, so maybe only 1-1.5 grams of dry gelatin. And maybe only 60 milligrams of DAS. 2 ml of a 3% solution of DAS is 60 milligrams of DAS. Think carefully about exactly how small of batches you need.

Another possibility is to not make sensitizer-incorporated tissue. Rather, make a traditional carbon tissue, and tray- or brush-sensitize the DAS onto the tissue, replicating the process one would use for dichromates. This way tests and samples of tissue that are no longer useful to you can be discarded with little cost (pigment and gelatin cost relatively little compared to DAS.) Just something to think about. If you've never carbon printed before, it will take a few tries to get a recipe nailed down.

Yet another alternative would be to use pre-made tissues (Bostick & Sullivan). Then you can get used to working with the DAS by tray- or brush-sensitizing without the additional complications of making tissue.

Lastly, DAS is very highly unlikely to work with traditional carbro recipes. Carbro relies on a completely different chemical reaction to harden gelatin than traditional carbon printing. In order to develop a carbro-like process with DAS, you would need find a chemical (or chemicals) that will react in proportion to the amount of silver in your bromide printer to break the azide groups in the DAS which would cause imagewise hardening of the gelatin. Certainly not impossible if you're skilled in chemistry. But it is extremely unlikely that the traditional carbro recipes will work.

Best of luck...

--Greg

Hey Greg, in your testing did you use water or alcohol as your solvent for the 3% solution? In reading the threads it seems both are viable?

From someone that's used to working with Potassium Dichromate w/ acetone, is spirit sensitizing with DAS similar?

 

[gmikol]

I have only made pre-sensitized tissues with DAS/water solution. I've never tried sensitizing tissues after pouring/drying.

Obviously, if brush-sensitizing with just a water solution, there's no problem.

I do add some isopropyl alcohol to my sensitized gelatin solution without any apparent problems. But I haven't tested compatibility with brush sensitization with isopropyl alcohol or acetone.

--Greg

 

[holmburgers]

I just had a look at FR 886,716. Gum is not mentioned there. The colloids listed in that patent are: gelatin, methyl cellulose and PVA/methyl cellulose.

Methyl cellulose, aka carboxy methyl cellulose or CMC gum is a commonplace ingredient for ceramicists and is used in glazes. It'd be fantastic if DAS and CMC gum could potentially used in a gum-bichromate like process. I'm curious to know more about Kees' synthetic colloid as well.

Also, does anyone know if PVA refers to polyvinyl acetate or polyvinyl alcohol?? I would assume PV-alcohol (Elmer's glue), but I'd like to be sure.

 

[keesbran]

Methyl cellulose, aka carboxy methyl cellulose or CMC gum is a commonplace ingredient for ceramicists and is used in glazes. It'd be fantastic if DAS and CMC gum could potentially used in a gum-bichromate like process. I'm curious to know more about Kees' synthetic colloid as well.

Also, does anyone know if PVA refers to polyvinyl acetate or polyvinyl alcohol?? I would assume PV-alcohol (Elmer's glue), but I'd like to be sure.

Hi, I could not resist to do some quick tests with DAS and methyl cellulose. A fairly thick 2,5% methylcellulose solution was 1:1 mixed with standard 3% DAS. Mixed in some lampblack watercolorpigment. This mix was applied on a gelatin sized and hardened watercolor paper. It was difficult to apply an even coating, much more difficult than with gum. After some testing I found out that a 15 sec (!) exposure under a bank of UV TL was sufficient. The methylcellulose shows a very heavy stain after exposure. The print can not be developed in cold water, nothing happens there. I found out that a rather warm bath or even a stream of warm water (±40°C) like with carbon worked well. So, yes it works!

When speaking of PVA I allways refer to PolyVinyl Alcohol, available under various brand names. I'm using Mowiol. Polyvinylacetate (PVAc) is very different and not suitable for pigment/colloïd printing because when dry, as far as I know, it is not water soluble anymore. It can be used as a sizing for paper. PVA works with DAS but not that good in my testing. I have found very good hardening and extemely high sensitivity with some polyvinylpyrolidones (PVP).

Kees

 

[holmburgers]

Awesome Kees, thanks for doing the experiment!

CMC gum is an oft overlooked material I feel, and here you've shown that it has potential for printing processes. It's cheaper than dirt and fairly easy to work with. It doesn't set like gelatin, which is both a good thing when you consider you don't need heat, and a bad thing when you realize it has to dry flat.

Thanks too for clarifying the PVA issue.

 

[Orioes]

Lastly, DAS is very highly unlikely to work with traditional carbro recipes. Carbro relies on a completely different chemical reaction to harden gelatin than traditional carbon printing. In order to develop a carbro-like process with DAS, you would need find a chemical (or chemicals) that will react in proportion to the amount of silver in your bromide printer to break the azide groups in the DAS which would cause imagewise hardening of the gelatin. Certainly not impossible if you're skilled in chemistry. But it is extremely unlikely that the traditional carbro recipes will work.

Best of luck...

--Greg

I suspected as much and having spent a few days (Far too short in my opinion) with Kosar's Light Sensitive Systems I even have some insight as to why. Though having read Kosar I think it may be possible to implement a carbro-like process by producing a dichro or diazo based process that is sensitive to visible light. Then you would either print on dichro/diazo coated paper and after exposure marry it to tissue (A la a mariotype) or expose the sensitized tissue directly in the enlarger. Unfortunately DAS doesn't seen to be in the class of diazonium compounds that are or can be made sensitive to visible light but until I can find such a compound I can experiment with it and try to dye sensitize dichromates.

As an aside if anyone hasn't already read Kosar buy, borrow or steal a copy. It is a fount of fascinating information and potential new paths of inquiry.

 

[david chalmers]

Hi
Is there still a group purchase option available for this DAS sensitiizer?
I am looking to purchase 1KG if possible.
thanks
David

 

[Halford]

Hi all,

Resurrecting this post -- did anything ever come of this? I am looking into alternatives to dichromate as a colloid sensitizer, since dichromate is going to be outlawed in Europe a year from now -- just as I'm getting really excited about what it can do :-/

I see Kees did some initial tests, but has anybody taken this further?

Thanks and have happy days,

Hal

 

[CMB]

What type of colloid? Phototypie may be of assistance: Dead Link Removed

 

[chrisaisenbrey]

Hi all,

Resurrecting this post -- did anything ever come of this? I am looking into alternatives to dichromate as a colloid sensitizer, since dichromate is going to be outlawed in Europe a year from now -- just as I'm getting really excited about what it can do :-/

I see Kees did some initial tests, but has anybody taken this further?

Thanks and have happy days,

Hal

I guess you are talking about
„Disodium 4,4′-diazidostilbene-2,2′-disulfonate tetrahydrate“ CAS 2718-90-3
(Other diazo components like speedball screen printing diazo seems not to work well)
For gelatin processes like carbon printing I would say it is a full replacement of dichromate.

Just the workflow has to be adapted since the DAS has to be added BEFORE the gelatin /pigment mixture is coated. But those sensitized pigment papers are very stable (some say for years).

I don’t know if somebody succeeded with other processes like gum printing.

 

[Thibault Duchesne]

Hi all!
I'm about to dive in that process using DAS sensitizer, I've been experimenting Carbon Transfer process since few month using Citrate base sensitizing, but it was not stable enough and had a hard time making consistent results... I order and receive some DAS few days ago and about to start again some experimentations. I wonder is the insolated tissue needs a bath in hydrogen peroxid as citrate based process did... Anyone here produced some images with DAS ? Thanks

 

[CMB]

Just now noticed your post. Are you still experimenting with DAS? How can I help?

Charles

 

[Aimee Danger]

Hi all!
I'm about to dive in that process using DAS sensitizer, I've been experimenting Carbon Transfer process since few month using Citrate base sensitizing, but it was not stable enough and had a hard time making consistent results... I order and receive some DAS few days ago and about to start again some experimentations. I wonder is the insolated tissue needs a bath in hydrogen peroxid as citrate based process did... Anyone here produced some images with DAS ? Thanks

Where did you purchase your DAS? How did it go?