Carbon Questions

[paradine]

This past week I was finally able to get a hold of all of the materials for carbon printing. Since then I've done two prints, the first with a digital negative. The results weren't overly favorable but I then made another print using a 120 negative and that came out much better with a couple exceptions.

I've attached the second image to this post.


My first question is in regard to the obnoxious streaks in the image (ignore the white crap on the image). I'm assuming those are because of uneven density in the coating of the potassium dichromate sensitizer. I'm using the spirit coating method outlined here: unblinkingeye.com/Articles/Carbon/carbon.html

(I apologize, my post count isn't high enough to post links.)

The first print that I attempted did not have uneven spaces however the brush strokes were definitely visible. I'm using the method outlined in the same link, starting vertically, then going horizontally, and finally diagonally with a one inch wide foam brush.

Other than tray sensitizing is there a better way to go about coating the carbon tissue?


My second question is about the "relief effect" in the carbon printing. There virtually isn't one from what I can see. I'm using fixed out RC paper; is it more prevalent on other art papers?

Other than that I'm quite pleased with the results, I can't wait to get some 4x5 negs and make prints from them.

[Andrew O'Neill]

That article by Sandy King is what got me into carbon transfer printing. It is only a starting place. What works for one, may not work too well for another. Carbonites are always tweaking here and there 'til they get a workflow that works. So, before concerning yourself with relief, iron out your workflow.
For such a small negative, how much sensitizer are you using? I use 10ml total solution for a 9x11 tissue. I prefer working with ammonium dichromate, diluted 1+1 with acetone or 99% isopropyl alcohol. I have never used potassium dichromate, so cannot comment. Brushing must be done quickly and do not over do it. I only brush up down, left right. I brush until the solution does not bead on the surface of the tissue. That should help eliminate any brush marks.
What pigment are you using? How much?
In the article, an 8% gelatin solution is used. I got "slightly" more relief by increasing the amount of gelatin to 10%, and decreasing pigment load (lampblack water colour) to 4%. Apparently, printing on RC or Yupo papers shows off the relief more, but I can't see any difference when compared to the same print on art paper.
Eventually you will realize that not all images are suitable for this process, especially if you are looking for relief effects. With the image that you provided, you should see the most relief where the greatest contrast areas are.... white against black. This will be more pronounced when wet, and less when dry.

I posted a video last month: http://www.youtube.com/watch?v=EmpTgDlsr3o

[paradine]

I'm not actually measuring out my sensitizer.. simply dipping the brush and coating once, drying, and then dipping and coating once more. I'll have to take more care in the measurements in that aspect.

I followed the article for making the glop to the exact for making one liter save for the pigment, substituting acetone for the alcohol, and lack of thymol. I used 24 grams of black india ink in the glop. I actually watched your a few days before starting the process and seeing the relief in your print was remarkable. However in both of my prints the gelatin is completely flat and really just looks like a silver gelatin print with an uneven border. I'll have to try adding more gelatin to the next batch of glop.


Thank you for your input. I've also ordered some more potassium dichromate and I think I'll attempt tray sensitizing.

[paradine]

I forgot to add this in my original post.. is it possible to use plexi or plate glass as a final support?

[Andrew O'Neill]

Don't see why not. Some people transfer their images onto aluminum panels. The glass/plexi would have to be coated with something like transparent acrylic polymer first.
Yes, bump up your gelatin to 100grams. Try that for a few tissues. Then try backing off on pigment to say about half of what you used (keeping gelatin at 100g). It's best to work with one variable at a time. Remember to keep really anal notes!

[Jim Graves]

Glass can be used as a final support for carbon without coating ... but requires special cleaning ... Bill Winkler has an article on Lightfarm detailing his process: Link

You can also prepare it with Silane Glass Treatment ... Bostick and Sullivan carries it: Link

Also try searching Bostick and Sullivan's Advanced Carbon forum: Link

[paulie]

before i switched to tray sensitizing due to having a baby in the house and the acetone fumes being overpowering, i used to measure out say 10ml of dichromate + acetone 1-1, and pour it over the tissue to swamp it and just gently pushed it around with a foam brush.

to prevent streaks the tissue must remain soaked and not be allowed to become dryed at all whilst brushing.

tray sensitizing is a lot easier, and less smelly, just refrigerate 1 litre of cold water with the appropriate percentage of dichromate pre mixed into the water, pour it in a tray and imerse the tissue for lets say 2min, pull out and gently squeegee. hang to dry.

occasionally pass the dichromate through a muslin cloth to prevent contaminates, top up if necessary, i have litre bottles from .25% - 2% dichromate

+ if more contrast is desired than .25 % then just shorten the soak time from 2 min - 1 1/2 min etc

hope this helps

[R Shaffer]

before i switched to tray sensitizing due to having a baby in the house and the acetone fumes being overpowering, i used to measure out say 10ml of dichromate + acetone 1-1, and pour it over the tissue to swamp it and just gently pushed it around with a foam brush.

to prevent streaks the tissue must remain soaked and not be allowed to become dryed at all whilst brushing.

tray sensitizing is a lot easier, and less smelly, just refrigerate 1 litre of cold water with the appropriate percentage of dichromate pre mixed into the water, pour it in a tray and imerse the tissue for lets say 2min, pull out and gently squeegee. hang to dry.

occasionally pass the dichromate through a muslin cloth to prevent contaminates, top up if necessary, i have litre bottles from .25% - 2% dichromate

+ if more contrast is desired than .25 % then just shorten the soak time from 2 min - 1 1/2 min etc

hope this helps

That is really interesting and I sure could do without the fumes from the acetone.

I would be curious if the dichromate concentration changes with use?

[Andrew O'Neill]

If acetone bothers you, then use 99% isopropyl alcohol.

[paulie]

That is really interesting and I sure could do without the fumes from the acetone.

I would be curious if the dichromate concentration changes with use?

ive been using the same bottles for 6 months and have noticed no changes
but then i also make test strips using the same solution each time so the tests match the sheets perfectly
works for me but others may have different opinions

the great thing about tray processing is that you dont have to buy acetone/alcohol