First test with carbon transfer.. why is this happening?

[glpozza]

Why there is this "border" in my print? It is were my tissue ended. Should I just cut it smaller or am I doing something wrong? It was printed on inkjet paper.
I've also identified contrast and sensibilization issues, wich I plan to fix on my next test.

 

[Vaughn]

My guess it is just carbon particles stuck to the inkjet paper. Inkjet paper is designed to tightly hold onto pigments/inks, so the paper might be the cause. When transferring to photo paper, I just wipe off any of it that is around the image after development with a soft cloth or paper towel.

 

[glpozza]

I've tried that. Most of the overexposed tissue was easly brushed away. This line is deep into the paper. I believe you are right about the inkjet paper, I just dont know why it happens only there.

 

[Vaughn]

Inkjet paper is coated (I believe) with clay particles...very small particles which greatly increases the surface area of the paper so that it can grab a lot of ink. To some extent I think there is an issue of "static cling", or something along that line, that tightly grabs onto gelatin and pigment very tightly. The upside is that transfer time for inkjet paper tends to be much shorter than for fixed out photo paper.

But the down side is that the pigment particles can be difficult to wash off the surface of the paper. I even had this problem with one type of photo paper (Oriental) -- I ended up with images that seemed slightly fogged. The problem did not happen with Ilford papers (but others have had no problem with oriental, so it is a bit confusing). I fought this issue for a year before going back to Ilford papers.

Using a different brand of inkjet paper might yield different results. Looking Good and Good Luck!

 

[glpozza]

I had no idea it could cause fog. It could be the cause of my low contrast (I'm using 4% potassium). I was reluctant in using photographic paper as it is much more expensive, at least until I get the process correct. For now I'll stop brushing away the overexposed gelatine, maybe achieving a less agressive visual result. Thank you, Vaughn.

 

[Vaughn]

"Fogging" is perhaps not the best of terms to use, as it is not due to the usual causes of fogging in photographic processes (fogged by light or chemical aging).

If you are having trouble getting a rich black, even with over-exposure, you might need a little more pigment in the mix. This will also increase contrast. And it would be a interesting experiment to sensitize with 2% just to see the difference it makes.

It appears you are using inkjet negatives. If this is correct, I suggest posting here:

http://www.largeformatphotography.info/forum/showthread.php?110457-Carbon-Transfer-Prints

Some very experience folks there!

Some great help available there!

 

[glpozza]

Thank you. I've posted my image there.

 

[Andrew O'Neill]

When I pour my tissue and then score along the magnetic frame to remove it, I get a slight ridge. If I don't mask outside of the tissue area prior to exposure, I also get this mark. I transfer onto acrylic sized art paper, so I can easily rub it off with my finger during development. Inkjet paper seems to grab onto it and not let go. I'd also be concerned about what appears to be brush marks in the print. Are you spirit sensitizing?

 

[glpozza]

Yes, I've seen the brush marks. I'll try to be more carefull in my next tissue, maybe use another tool for that. Could you explain your sizing process? I´ve used PVA (glue), but it melted in the warm wather.

 

[Vaughn]

Brush marks -- what I am seeing in your print could be from stopping too soon when brushing. Brush until there is no more sensitizer pooling anywhere on the surface of the tissue. You should feel the brush start to drag across the tissue surface. There is no danger of scratching the surface of the tissue from over-brushing, at least from what I have observed over the last 20 years.

Any kind of brush will do -- as long as it does not leave any of the brush hairs behind! I use regular household paint brushes, others have have great results with foam brushes.

 

[glpozza]

Nice. I thought it was from missing some parts of the tissue. I really was worried about scratching the tissue.
Are you using acrylic medium? Isn't it water soluble?

 

[glpozza]

To finish this post. I've tested acrylic gesso and got really good results. The brush marks are gone and now I'll focus in the contrast. Thank you all.

 

[Vaughn]

Great to hear!

 

[glpozza]

Updating. Sized art paper, reduced the tissue thickness by 50 % and a really careless brushing.

 

[Vaughn]

Looking good. Perhaps using the same amount of dichromate solution, but diluting it more might make brushing more even. I dilute mine 1:3 for a total of 20ml per 100 sq inches (645 sq cm), applied half at a time.

 

[glpozza]

Yes! Your post made me realize something so obvious I have been doing wrong that I'm ashamed to post here. What about exposure? I guess there is a correlation between pigment/sensitizer/exposure, but is there a correct combination or is it just about the results? Both images were exposed for 10 minutes under a 45w uv light.

 

[Andrew O'Neill]

I use 10ml total solution and stop brushing (with foam brush) just before sensitizer has evaporated. If I keep brushing beyond this point, I usually end up with brush marks.

 

[Vaughn]

I have been lucky. I brush (paint brush, 1" to 1.5" wide) until the sensitizer is all gone, then a little more to get ride of any last liquid of the brush. I notice what looks like scratches on the tissue. but upon closer observation, they appear to be streaks of uneven swelling of the tissue. When I hang the tissue to dry, these lines disappear as the surface swelling and then drying (w/ fan) smooths out the surface of the tissue. While my scenes tend to be busy, which can hide a lot of sins, I have enough images with smooth tonality that I would see any scratches. Plus any surface defects get hidden -- in the final print using the single transfer, the surface of the tissue becomes the bottom of the image (next to the permanent support paper) due to the transfer.

 

[glpozza]

Now you got me confused. Both of you have diferent positions on when one should stop brushing. But, as Vaughn pointed out, the scratches would be under the image in the single transfer method, so any brush marks are result of too little sensitizer on that specific portion of the image (right?). Also, would a foam brush improve significantly the distribution over the tissue?

 

[Andrew O'Neill]

I wouldn't know. I've only ever used a foam brush.

 

[Vaughn]

I wouldn't know. I've only ever used a foam brush.

And I have never used a foam brush.

That is the 'problem' with carbon printing. Each person has their own way of working that they have established thru trial and error and have found has worked best for them. Andrew coats with half the liquid I do, thus will have different issues to deal with than the issues I have...and both of us have come up with methods that work best for us. There is no "right and only' way.

I feel that I get good even coverage with my method. Gelatin does not instantaneously swell, thus the gelatin that gets hit with liquid first will swell before the later places to get wet, but eventually the whole tissue swells to the same amount.

Eventually you will try this and that and come up with a method that gives you clean repeatable results for your working conditions.

 

[glpozza]

Yes, I've seen that with all the other alt-processes, but carbon seems to be te more particular in this aspect. I'll keep using the same brush and try with a small amout of sensitizer. It's raining a lot here, and I'm hoping to keep a reasonable drying time. Thank you all a lot for sharing your experiences.

 

[Mat23]

Howdy,
Not sure if this thread is still active but if it is could I have a little guidance please on coating thickness?
I have magnetic strip of around 1mm but after pouring it just looked way too think and I suppose I thought it would take forever to dry (Melbourne winter) so I scraped off and repoured it much thinner.
I`m beginning to think I made a mistake as my initial tests are just not happening.
Is there a minimum thickness or is the 1mm the minimum?

Cheers
Mat

 

[Vaughn]

The main requirement for gelatin thickness is that the gelatin is thick enough so that one does not expose (tan) so deep into the gelatin layer that one tans the gelatin all the way down to the tissue support. You will know this happens if the gelatin does not release from the tissue support -- and instead rips the image off the final support when trying to remove the tissupport in the development bath.

Having the tissue too thick just increases drying time...so one aims for a happy medium.

 

[Vaughn]

A nice way to sensitize tissue is to use a small (2" to 4" wide) foam roller instead of a brush.

Something like this: https://www.homedepot.com/p/4-in-x-...i-Roller-Cover-5-Pack-HD-MR-200-5-4/202097452