Carbon printing: small bubbles around the print

Lightfire

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It's going to be my third attempt to do a carbon print. Everything is going okay, so far but I always have the same problem: there are a lot of ugly tiny bubbles around the whole pic. I tried to change mating time/water temperature, developing temperature... But it didn't do anything about the defect I get.
If anybody had the same problem, it would be great to know any possible solutions of the problem.

P.s. I tried to use different papers (fiber-based+fixed, yupo, rc-papers). It worked better with some expired soviet fiber-based paper, which has a very bad gelatine coating, because it's almost unhardened. As the result, there weren't any tiny bubbles, but there were a lot of fog in highlights. But anyway, I saw a lot of great examples of carbon prints transferred to yupo paper, which didn't have such a problem with bubbles...
 

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Vaughn

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1) How long do you let the glop rest after mixing in all the ingredients? I prefer to let the glop sit in a warm water bath for several hours after to let air escape.

2) Are you adding any alcohol to the glop? This reduces bubbles in the glop by reducing surface tension.

3) Have you let your transfer water sit for 24 to 48 hours to de-gas? Adding alcohol can help here, too. Boiling water, then letting it cool is another way to quickly de-gass water. Some folks can use water straight out of the tap, but they are lucky as this is not usually a good idea.

4) - Perhaps clean the final support surface with alcohol. Just a wild guess and its easy to do.
 
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Lightfire

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Andrew O'Neill said:
Try less exposure. Too much will result in blisters.
Click to expand...

I already did. It doesn't seem to be affected by exposure time in this case. They appear even if the print was underexposed.


1)I always let it rest for a couple of hours, ~2-3;

2)During my previous attempt I added some ethanol to the glop, but it didn't seem to help to get rid of the bubbles. I wonder, is it okay to add ethanol instead of isopropyl? I mean, I can get isopropyl, but I already have some 70% ethanol, so... If it works, I might try to add it to a new glop;

3)I used distilled water that was left in an open bottle for a couple if days. But... Only for mating. I used ordinary tap water for developing the print. Besides that, I guess its quality is worse than in USA/most of European countries, so maybe that fact could affect the result as well. I guess I'll try to boil some distilled water to use it for both developing and mating;

4)Hmm... I'll just try to do it. But again, is it okay to use ethanol for such purposes?

Thank you very much for your advice. I hope something of those will work in the way I need.
 

Vaughn

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Hmmm...sounds like you are doing a good job. I believe ethanol should work as well, but I have used only isopropyl (70%, 91% and 100%...does not seem to make a difference so far). Some water sources just has more air in it -- and one's pipes and faucets can add air into the water.

Bubbles that cause raised bumps in the surface of the print indicate air trapped (or generated somehow) between the tissue and the tissue support. Bubbles in the glop itself will leave nice round white areas in the print (the bubbles replace the pigmented gelatin -- so your issue probably is not in the glop itself.

Bubbles in the developing water should have no affect on the print, as that is a surface issue.

Good luck in tracking this all down!

PS -- I have only used dichromates to sensitize
 
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Lightfire

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Right, and that is the problem. Because they are between the transferred gelatin and the support. I checked the tissues for bubbles after coating and I definitely didn't see any. But... There's another problem -- the dust. May it be the reason of the defect? I mean, although I cover the tissues during drying to avoid the dust falling on them, it doesn't help perfectly. I'm not sure if it affects the result tho...

P. S.
I use potassium dichromate as well. I tried both brush coating with alcohol and soaking in dichromate solution. Both worked well
 

Vaughn

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I would not think the dust would result in bubbles. People have reported a bubble problem on Yupo that was miminized by washing the surface of the Yupo first. No experience with Yupo as a final support, though.

Occasionally (but rare) I'll get a print that has a group of micro-bubbles on it like yours -- with nothing different being done with that print compared to the bubble-free prints.

I stick to brush sensitizing to deliver the exact amount of dichromate I want...minimizes the dichromate I use.
 

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Lightfire

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I checked the print after it's completely dry and... It doesn't look as bad as it could be. I mean, the blisters are still there, but they don't look like some kind of "skin disease". I had much worse bubbles before. I guess, I'll simply try to get rid of any gas in mating tray at all and clean a sheet of fixed fiber-based paper with alcohol. And, probably, it's still a good idea to add some alcohol to the glop. I'll reply here after another attempt. Hope this time it's going to be better.
 

Vaughn

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Good luck! I do not think I got an image yet on my third attempt, so you are ahead of schedule!
 

Andrew O'Neill

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If you're absolutely certain it's not due to exposure... Assuming you have done an exposure test... What is the temperature of your development bath? I maintain a 42C temp. Higher than 45C gives me blisters.
 
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Lightfire

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Andrew O'Neill said:
If you're absolutely certain it's not due to exposure... Assuming you have done an exposure test... What is the temperature of your development bath? I maintain a 42C temp. Higher than 45C gives me blisters.
Click to expand...
I actually made a test print and it had blisters in all parts of the pic, including the ones which were underexposed.

The temperature of my development bath was about 38C. During my previous attempt I used a higher temperature. The blisters were worse. But the problem didn't completely dissapear with lowering the temperature...
 

Andrew O'Neill

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Personally I do not care for fixed out RC papers or Yupo. It's more difficult to control blisters... And I don't care for the plastic look. I do like fixed out fibre based papers, especially matte. But... My favourite is acrylic sized art papers. Try sizing your own papers. Acrylic is the quickest, and easiest way. No hardener required. Matte and glossy types.
 

Andrew O'Neill

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Also, tap water that is more alkaline will interfere with your transfers. It won't matter what substrate your using. Alkaline water is bad. My tap water here in Vancouver, BC is alkaline. Adding a splash of vinegar to the mating bath makes the water acidic. If you are sure that your water isn't alkaline, then try "dead" water. Keep tap water in a couple of jugs. It will be all gassed out when you go to use it... I used to use dead water until I realised that the issue was alkaline base.
 
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Lightfire

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It seems that fibre-based works better, actually. I have about 400 sheets of old paper, which isn't that good for silver-gelatine printing already, so I use it. I just tried RC paper and yupo for transferring as well.

Do you dilute acrylic gesso with water for sizing? It seems interesting to try, although I'd like to finish with fiber-based paper firstly.

Actually, I have problems with washing cyanotypes if I don't add some acid to my tap water. But... Should I try to use slightly acidic "dead" water only for mating? Or for development as well? I mean, I actually did mating in distilled water during the last time. But I guess it's better to check its PH up as well.
 

Andrew O'Neill

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I dilute acrylic medium 1+1 with distilled water. I apply four coats...drying between coats only takes about 15 minutes. I use a high density foam roller (the small "sausage" rollers).
I only add vinegar to the mating bath.. and a bit of isopropyl alcohol to eliminate micro bubbles (I've accidently missed this step once with no issue...just a habit I got into years ago).
My tissue is soaked for 1:30. The sized paper is not soaked. It goes in when I mate them, then pull them out together.
 

Andrew O'Neill

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and I use the "mate, no wait" method. Once the tissue and substrate are mated, and squeegeed, I prepare the development bath and in they go.
 

Andrew O'Neill

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Sorry, I'm throwing too much at you. Just try the vinegar in the mating bath trick and see what happens. Gotta teach my photo students now! Cheers!
 
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Lightfire

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Thank you all for your advice! They are definitely helpful and help to understand the process better.

I tried to use boiled water with additions of citric acid and ethanol for the mating bath. And...
When the print was wet, I could see some blisters, but when it completely dried... The surface was just fine.

I've got another problem, tho. The emulsion flakes off during the development. I guess it was a mistake to avoid leaving a safe edge around the negative. But in the same time... I know some people don't use a safe edge at all and it works fine. If you have any advice about that problem, it would be just incredible.

P. S. It was a print with an exposure test. I've been trying to get clear whites with the negative I have and I finally did. I mean, the contrast is too strong currently, but it's easier to manage it than dealing with other defects I mentioned.
 

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The safe edge is needed. At this stage of learning the process it will be important not to deviate too far from the standard practices of the process (such as a safe edge)...so many things can go wrong! LOL!

Once experience is gained and enough mistakes are made, then one can start tweaking the process to best fit one's vision.
 

Andrew O'Neill

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I ALWAYS use a safe edge... I use litho tape. It really is necessary, in my opinion. Even black construction paper with a hole cut out, and negative taped to it works great.
 
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Lightfire

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Thank you very much. I'll try again, but with leaving a safe edge around my negative. It's a bit difficult to keep everything on mind currently, but my experience shows that it's just a matter of time.

By the way, how should I agitate the print during the development bath? I mean, after I separated the tissue from the final support.
 

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Many different methods -- I leave the print face up, but under the water at all times. I grab the paper between index finger and thumb at a corner. I give the print sharp short shakes -- almost vibrating the unexposed gelatin off. Occasionally I will lift the print out of the hot water and slip it back in. Halfway thru, I will put the print in a tray of clean hot water to finish developing. I can see the image better and I like to get the image surface away from all that extra carbon in the developing water.

Time-wise, development is usually less than 15 minutes for my thicker tissues (a lot of unexposed gelatin to melt off). I lift the print by a corner all the way out of the water to see if any black flows off the bottom corner. If not, then developing is done unless I wish to reduce the print a little with longer development.

If a corner starts to separate and lift off the paper (frilling), reduce aggitation -- if you can keep the lift to a minimum and do not stretch the gelatin, corners can often be laid down after the last wash and they'll re-attach. Sometimes one can finish developing with the print on a sloped piece of glass and pouring hot water gently over the print -- with the frilled part of the print at the lower end. Careful not to pour as to force water between the paper and the image on the top section.
 
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Lightfire

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Alright, another attempt. Now it's much better in terms of transfer. I decided to try using acrylic-sized watercolor paper as the final support. It worked well!

The top part of the print looks just fine, but something went a bit wrong on the bottom part of the pic. The emulsion slightly started flaking off, so I didn't use any agitation during the development. I just put the print face down into the tray. As the result, the bottom of the age shows a bit of flaking of the emulsion and some bubbles under it, while the top part looks okay. Did I soak the tissue for too long? (1 minute). I didn't soak the paper sheet, just put it into water for mating when the time was running out. Thank you again for the advice, by the way!
 
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Lightfire

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Hmm, I decided to try one more time, using a weaker negative (it would be better to prepare a normal one from the beginning, but I'll do it later). I tried to make the mating time a bit shorter and left the "sandwich" under the pressure for additional 20 minutes. There's an improvement for sure. No flaking, no blisters... But... A small part of the emulsion looks like it was "moved". Could it happen because of some excessive water under the tissue? Or maybe I squeezed it to strongly while I was removing excessive water from the "sandwich"?

 
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