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.
Last edited by holmburgers; 07-13-2011 at 10:33 AM.
From the film shooters will rise a well developed practice of the alternative processes that, in time, will be adopted in the age of the digital image to free it from the extreme boringness of pressing print.
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:
The first one has the same CAS# (41432-19-3) as a widely-used screen emulsion sensitizer.
--Greg
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.
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.
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.
David--
I'm glad to hear that your first attempts worked out well for you.
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.
I use a 300w Osram UltraVitalux bulb, which is what I started with 18 months ago, it is fast but no longer suitable, I am building a bank of BL tubes so I can make bigger prints.
The recieving support in Tod Ganglers video is probably mylar sized with dichromated albumen. The process is described in a file on the Yahoo Carbon Forum by Gary Baker http://tech.groups.yahoo.com/group/C...0Art%20Papers/
The Kiwo agents are trying to get me some sensitiser seperate to emulsion, if it happens it will take time as it will probably have to come from the US.
I can post my wedges sometime today but they are stained yellow, I have no way of trying the clearing baths recomended until I get some potassium permangenate.
Note I made all my 4 wedges within 24 hours of pouring, I dont know how long the tissue will last.
Thank you so much for your contributions to this thread, David.
A couple of random points:
1) The middle one is the one you transferred to the back of RC paper?
2) Even at 20 mins, it seems like it could use a little more exposure.
3) Do you have an MSDS for the sensitizer? The Kiwo documentation describes this as "Diazo Sensitizer #14", but I can't find any MSDS for this. It would be nice to know what the actual chemical is. I suspect it is likely this one: 4-DIAZODIPHENYLAMINE/FORMALDEHYDE CONDENSATE HYDROGEN SULFATE (CAS# 41432-19-3) since that is what is in Kiwo sensitizer #1-#11.
4) Can you post the 2ml/50ml wedges as well, for comparison?
Adv Reply
Originally Posted by gmikol
