Carbon Transfer Questions

[holmburgers]

I know there are a lot of variables involved (light source, sensitization technique) and so each person should do his or her own testing.. but, do you think that a reliable method to translate variable-contrast printing grade to sensitization concentration can exist?

It'd be very convenient to be able to find the desired contrast w/ silver-gelatin and that would leave you with only the exposure time to figure out when switching to carbon.

 

[Vaughn]

Well, if my negative can make any kind of decent silver print, using any paper/filter/developer combo, then I know that I do not have enough contrast for a carbon print (or at least for the way I make them -- YMMD).

If a negative has too much contrast to make a platinum print with no contrast agent added (Na2, Potassium chlorate, or dichromate), then I know I have a negative that will make a great carbon print.

I suppose the best way is checking with a densitometer, but I do not have one.

 

[PVia]

If a negative has too much contrast to make a platinum print with no contrast agent added (Na2, Potassium chlorate, or dichromate), then I know I have a negative that will make a great carbon print.

Assuming the above, what is your dichromate dilution?

Oh...and is there a way to determine equal dilutions of either ammonium or potassium dichromates? IOW, a 3% amm di is equal to a ?% pot di solution...

 

[Vaughn]

8% AM, diluted 1:3 (one part stock to three parts acetone). For an 8x10 (9x11 tissue) that is 5ml:15ml for brush sensitizing.

 

[Vlad Soare]

I'm getting close. I used a 1% solution, and the contrast is much better, though there's still room for improvement. I think I'll try 0.75% next time. I used a negative that gives a good straight print on grade 3 paper.
I think I know what happened last time, when the tissue didn't peel from the final support. The tissue was bigger than the negative, and I didn't mask the edges, so they over-hardened, probably all the way to the support.

I know there are a lot of variables involved (light source, sensitization technique) and so each person should do his or her own testing.. but, do you think that a reliable method to translate variable-contrast printing grade to sensitization concentration can exist?

I think it can. I think that if the following things:
- brand and concentration of gelatin
- type of pigment and concentration
- concentration of sensitizer
- duration of the sensitizing stage
- sensitizing procedure
- time between sensitizing and exposure
- UV lamp used
- time between exposure and transfer
are always the same, and both the glop and the sensitizer are made with distilled water, and the sensitizer is always fresh, then a certain concentration of sensitizer should always give the same contrast grade.
But that's just a guess, based more on common sense than experience. We all know that photographic processes can sometimes elude common sense.

How long do your tissues take to dry after sensitizing? After two hours mine felt dry to the touch. I gave it one more hour for good measure and then exposed it. It seemed to be completely dry, but after the exposure I had trouble separating the negative from the tissue.
How long should I wait for the tissue to dry before exposing it? Simple tactile assessment doesn't seem to work.

 

[Vaughn]

Good looking print! Congrats!!

Too many unknown variables to answer your question about drying time:

How much water do you use in sensitizing a tissue? This determines how fast it will dry. For an 8x10 I use 15ml acetone and 5ml of stock AD solution, so I am adding 5ml of water to the tissue. If I used 70% alcohol instead of the acetone, then there is almost twice as much water added to the tissue (9.5 ml of water total). If I use 91% alcohol, than there is 25% more water than using acetone.

RH of the room where the tissue is drying is important to know.

Do you use a fan on the tissue while drying? Two hours should be enough if a fan is used.

How hot does the glass over the tissue get during exposure? Too hot will draw moisture from the tissue towards the negative. Slightly warm is okay, very hot is not.

 

[holmburgers]

I like the tone of your print, a nice "eggplant"! Was your negative enlarged, or is it natively LF? Digital neg?

 

[Vlad Soare]

Thanks, Vaughn. I see your point. Too many things can affect the drying time. I sensitized the tissue by immersing it fully in sensitizer and then agitating the tray vigorously for three minutes. I used just potassium dichromate in water, no alcohol or acetone, then left the tissue to dry naturally, no fan or anything. The glass gets very slightly warm, barely noticeably.
Next time I'll try to give it more time before the exposure. Anyway, the negative wasn't damaged because I exposed it emulsion side up. Besides, even the back side looks fine, no stuck pieces of gelatin or anything like that.

Chris, the negative is a native 4x5". HP5+ developed in ABC Pyro.

 

[Vaughn]

Yes, tissue sensitized that way would take much longer to dry -- the fan would help a lot.

You might also try reducing the sugar content, but that is a whole other kettle of fish.

The damage I have had to film emulsion due to damp tissue has been a local change in the gloss of the emulsion -- enough to affect the way UV passes through and can be seen as blotches in areas of even tonality...a bummer.

And then there was the 11x14 neg that became glued to the tissue when I let the glass get way too hot. When I separated the negative from the tissue, I accidently tore the 11x14 negative in half. This was in a demo for one of our photo classes -- quite dramatic!

 

[paul_c5x4]

I used just potassium dichromate in water, no alcohol or acetone, then left the tissue to dry naturally, no fan or anything.

What ever you do, do not use isopropyl alcohol (CAS number 67-63-0) with any potassium dichromate solution - It will cause the dichromate to crystallize out. Found that out the hard way

 

[holmburgers]

If it hasn't been explicity said, I'll say it... Vaughn is doing spirit sensitization with ammonium dichromate and Vlad's talking about tray sensitization with potassium dichromate.

There, I said it!

(just incase someone lurking in the shadows was confused)

 

[Hexavalent]

What ever you do, do not use isopropyl alcohol (CAS number 67-63-0) with any potassium dichromate solution - It will cause the dichromate to crystallize out. Found that out the hard way

I use 50/50 isopropyl and water all the time for a 2% K dichro solution - it does not precipitate.

 

[Vaughn]

What ever you do, do not use isopropyl alcohol (CAS number 67-63-0) with any potassium dichromate solution - It will cause the dichromate to crystallize out. Found that out the hard way

That is what I have been told, yet people have used PD and isopropyl with no problem when tray sensitizing -- a confusing situation.

When I returned to carbon printing after several years of doing platinum printing instead, I had AD and isopropyl turn dark after mixing -- I had no problems before. Same AM, -- perhaps the additives to the isopropyl had changed (which is one of the reasons why I switched to acetone.)

So it is not as cut-and-dried as one would think.

 

[Hexavalent]

I should mention that I use only 99.953 % pure (electronics grade) isopropyl, not the "rubbing alcohol" from the drugstore that often contains fragrance, colour, GONW etc.,

Also, gradually adding the alcohol, rather than dumping it in lessens the chance of precipitation, as does using distilled/rev-osmosis water.
Phase of the moon is probably a significant factor

 

[holmburgers]

...Phase of the moon is probably a significant factor

I'm pretty sure I read something to this effect in an old archaic book on photography. Any idea what that would've been?

I mean, I'm like most people in that I plan my life around the movement of celestial bodies, but what effect could this have on my photos? Do I get more megapixels???

 

[Vaughn]

That is what I have been using lately to add to the glop to reduce bubbles, though it might be a grade higher since it says 100% -- tho I suppose once opened it sucks a little bit of moisture in from the air and is no longer 100%. I don't trust the "rubbing alcohol" anymore...at least not for adding to AD/PD.

Just re-read the bottle -- it is 100%, corrected for water. Water is listed at 0.008%

 

[Curt]

Two questions about comments previously posted. One is RH, is there a decent RH meter that one can purchase and use to record the humidity levels and keep track of them seasonally. The second one is another that Vaughn mentioned, what can I use with 11X14 and or ULF negatives to protect the negative from sticking and ruination from exposure. I've not had any sticking with the NuArc but with a bulb, Eye, I can see the heat building up. Heat was a problem with the Sun too I've heard, was it Jim Graves before getting a NuArc.

Vlad, that's a nice portrait, are they your parents, archivally it's going to last a long long time, one good reason to make carbon prints. Well done, keep asking questions, we all learn a lot from them and it helps to re-discuss topics and clear up partial information some have.

Best,
Curt

 

[Vaughn]

hello Curt!

I use Clear bags http://www.clearbags.com/crystal-clear-bags/protective-closure-bags

Here is the 11x14 size http://www.clearbags.com/crystal-cl...-14-1-8-crystal-clear-protective-286x359.html

A hundred of them for $13

I cut off the glue flap part and just put the negative in the bag -- protects both sides that way -- or cut them up as single layered sheets. Most Art supply places carry them and are occasionally on sale.

RH meters -- I have something like this -- http://www.grainger.com/Grainger/GENERAL-Temperature-and-Humidity-Meter-3LPF7?Pid=search

Cheap, really only accurate plus or minus 5%, but that is all I need. I got mine through Light Impressions (who I don't really deal with anymore). It is 55% right now in the house with rain outside. Bumps up to 80% when I have all three of my boys here -- showers, cooking, etc!

Vaughn

 

[Vlad Soare]

Vlad, that's a nice portrait, are they your parents,

Thanks, Curt. Yes, they're my parents.

 

[Vlad Soare]

With 0.75% and a shorter exposure it looks a little better.
This time I had no bubbles in the glop (the big white spots that still remain are either part of the image itself, or dust in my scanner), but there is something new this time. You can see it on my father's right forearm, and on the corner of the bench by his right sleeve. It's a bunch of very small spots where the gelatin is swollen. It looks like it didn't stick well to the support.
I think I had air bubbles in the water when I mated the exposed tissue with the support. Am I right?

Anyway, the process doesn't seem to be too difficult. Time consuming, yes, but not difficult. My next step will be to make some contrasty 8x10" negatives. I can't wait.

 

[Vaughn]

If the bubbles are white or lighter than the surrounding areas, usually those are bubbles in the glop when poured. Trapped bubbles during mating will usually have the proper tonality, but will be raised.

But things are looking good!

Vaughn

 

[Curt]

hello Curt!

I use Clear bags http://www.clearbags.com/crystal-clear-bags/protective-closure-bags

Here is the 11x14 size http://www.clearbags.com/crystal-cl...-14-1-8-crystal-clear-protective-286x359.html

A hundred of them for $13

I cut off the glue flap part and just put the negative in the bag -- protects both sides that way -- or cut them up as single layered sheets. Most Art supply places carry them and are occasionally on sale.

RH meters -- I have something like this -- http://www.grainger.com/Grainger/GENERAL-Temperature-and-Humidity-Meter-3LPF7?Pid=search

Cheap, really only accurate plus or minus 5%, but that is all I need. I got mine through Light Impressions (who I don't really deal with anymore). It is 55% right now in the house with rain outside. Bumps up to 80% when I have all three of my boys here -- showers, cooking, etc!

Vaughn

Thanks Vaughn, I imagined they didn't come in that size for some reason. I can see where the meter would come in handy for the extreme weather changes.

 

[Jim Fitzgerald]

Curt. I picked up a RH meter from the garden department at Lowes for 8 bucks. Shows temps and RH. How accurate? It gets me in the ball park. I have noticed that humidity plays a part as does the heat build up in my exposure unit. I use a NuArc 26 1KS and if I have an area of light tones or skin tones I get blotching from the heat pulling moisture up from the tissue and trapping it at the Mylar. I think that for smooth tones and portraits an exposure unit like BLB may be the answer. Anyone using a NuArc and printing light tones such as snow or skin or sky getting clear highlights? I've been told it is a humidity problem. I've even let the tissue dry for several hours after sensitizing with no change in result and I filter the hell out of my glop. Cycles of the moon?

 

[Vaughn]

My NuArc is a 1000W unit. I have to hit the button several times (set on 99 units) to get a full exposure with most negs. I usually hit it and leave the room. So there is time in between exposures. This keeps the glass of the vacuum frame from heating up, as there is a cooling down time between. When I over-rode the timer and did a continous long exposure, it got too hot.

When I am using the 750W merc vapor lamp, I have fan blowing cool air from the outside over the glass of the contact printing frame to keep it cool.

 

[PVia]

Vaughn, how long are those 99 unit exposures? Everyone's nuarcs are set differently, the only thing that is constant is actual time, with the variables being the age of the bulb, the individual negative and dichromate sensitizer. (Actually, I know...there's a million other variables...)

But I am curious about this...

Jim, how long are your nuarc exposures in minutes? I have the rest of your variables elsewhere from talking to you this morning...