Carbon Transfer Questions

[Vaughn]

Not very long -- 6 minutes or something like that. I have to hit the on button 5 or 6 times. But it does allow things to cool down some.

I assume you meant "the only thing that is constant is actual light output per unit", as it is the time that varies by the light out-put of the bulb (units are longer when the bulb is cold, and shortens as the bulb warms up and its light out-put increases.

I have the NuArc N1000 Instant Mercury Printer.

 

[Jim Fitzgerald]

Well, I have Gordon Chapples old NuArc 26 1KS unit. It goes to 999 units. 60 units is about a minute and a half. I'm typically exposing for 10 to 18 minutes.It does build up heat. I guess I should try multiple exposures with a cool down in between so I don't pull out to much moisture in the tissue. I think it may be easier for me to build a BLB unit to do the portrait images I wish to do.

 

[PVia]

Vaughn, I meant that if two people have identical Nuarcs, the light units are not exactly the same because the integrator may be calibrated differently, ie, Jim's machine does 60 units in 1 1/2 min as he notes. 60 units on my 26 1KS is 4 minutes. Same amount of light hits the glass, though, when counting by minutes (assuming new bulbs, theoretically speaking).

 

[PVia]

Jim, 10 to 18 minutes is a good benchmark for me...and based on my extremely limited experience in matters carbon, looks like where I am headed. Much thanks for this info...and for earlier today.

Thanks to both you and Vaughn, I have some more tweaking to do and another OCD to add to my neuroses ;-)

You guys are the best!

 

[Jim Fitzgerald]

Paul, you are welcome. Yes, the carbon monster is a beast... but when you tame it just a bit it gets really fun. Now that my 14x17 is done I can get back to work. I have 14 8x10 sheets to develop tonight and tomorrow I hope to get back to carbon printing. I do need to make some more tissue as I have workshops on the 12-13 and the 19-20th. Love to teach carbon.

 

[Jim Graves]

I thought the NuArcs were adjustable.

 

[Louis Nargi]

I went to a photo meeting tonight in my area and we were talking about this process. I found it very interesting.

 

[Jim Fitzgerald]

Jim, the Nuarcs are adjustable. I'd have to call Israel if I wanted to adjust mine. I have my times dialed in so no messing around for me. I did put a fan on the glass last night while doing a couple of test prints and it looks like that helped with my moisture problem. I'll try an experiment on a portrait this weekend.

 

[ghostcount]

@Jim F.

Have you tried cooling in between full exposure time? I mean if you find that a print takes 250 light units to be exposed properly, can you just do 5 increments of 50 light units and let the whole thing cool off for a few minutes between increments? I might try it this weekend but since I'm not as intimate with my NuArc I was wondering if this technique gives the same exposure. It could help in mitigating tonal discrepancies due to moisture.

 

[Vaughn]

Jim, mine NuArc is an enclosed system. I'd have to by-pass the safety switch (which keeps the lamp from being turned on when the door is open) in order to run an extra fan on it. I'll just keep doing multiple short exposures with time to cool off in between. Glad you found a way to keep yours cool with longer exposures!

 

[Jim Fitzgerald]

I'm going to do a test image this weekend and will report back. I also have an inexpensive dehumidifier coming in to control the humidity of my darkroom. It was 56% when I did the last two exposures. My tissue dried for 3 hours after sensitizing. I think the additional fan may be the answer I have been looking for for a long time. I'll know in a couple of days. If I had to do multiple exposures with a cool down period in between it would take way to long to make a print IMHO. If that was the case I'd build a BLB unit instead. I may still do that to have an additional unit to use.

 

[holmburgers]

I went to a photo meeting tonight in my area and we were talking about this process. I found it very interesting.

It really is an incredible process. To think that you can embed almost anything you want inside the gelatin, and then make a photograph with it, certainly allows for the most flexibility in any photographic process.

Not to mention that the results can be completely permanent. As long as its support is a high-quality paper (or similar) the pigment image will outlast just about anything.

And then of course there's tri-color carbon...

 

[Jim Fitzgerald]

Got to get the monochrome down before the quest to color begins!!

 

[PVia]

I thought the NuArcs were adjustable.

The NuArc's light output is not adjustable. It's on or off.

The unit's integrator counts the units of light that are emitted. As your bulb ages, the light emitted gets weaker and therefore it takes more time to reach the same amount of units.

So, if you know that an exposure for a certain process is 125 units with your machine, you will still get good exposures as the bulb ages, exactly 125 units.

Some people like to calibrate so that 1 unit = 1 second. I've never calibrated mine, which is approx 1 unit = 4 seconds. My 125 unit exposure is 8.3 minutes, while someone else's 125 unit exposure may be a bit over 2 minutes.

 

[Jim Fitzgerald]

Paul, I have found that my exposures run anywhere from 10-18 minutes depending on the density of the image. I pour a thick tissue and expose deep into the tissue. When doing this the NuArc builds up heat. Putting a fan directed at the vacuum glass helps to keep it cool and it looks like it may eliminate the problem I have been having keeping my skies clean. I'm not going to try to adjust the integrator and you are right. The integrator is nice to have. It keeps things consistent as the bulb ages. I have been able to repeat images referring to my notes. You have controls with carbon you just have to have a good work flow.

 

[holmburgers]

Got to get the monochrome down before the quest to color begins!!

I know, I know...

This is kinda like the proverbial you'll shoot your eye out.

 

[Andrew O'Neill]

8x10 (roughly) carbon print from digital negative (looks identical to pictorico. got it from a local screen printing supply co.) from 4x5 HP5 negative. Tissue contains 4g of lamp black pigment. Sensitized with 8% AD diluted 1+1 with acetone. Rising Stonehenge paper sized with acrylic polymer.
The image is of a very old, abandoned Ukranian Orthodox church, located in east central Saskatchewan. These beauties dot the prairie landscape up here. The August day I shot this, the temperature was 40C and very, very dry.

 

[PVia]

Very nice, Andrew...

 

[PVia]

The integrator function in the NuArc is one of those things that are hard to understand at first, because the integrator numbers are totally arbitrary from machine to machine. In the example I mention above, even though the numbers are the same, one exposure is 1/4 that of the other.

 

[PVia]

Paul, I have found that my exposures run anywhere from 10-18 minutes depending on the density of the image. I pour a thick tissue and expose deep into the tissue. When doing this the NuArc builds up heat. Putting a fan directed at the vacuum glass helps to keep it cool and it looks like it may eliminate the problem I have been having keeping my skies clean. I'm not going to try to adjust the integrator and you are right. The integrator is nice to have. It keeps things consistent as the bulb ages. I have been able to repeat images referring to my notes. You have controls with carbon you just have to have a good work flow.

Jim, I haven't explored this enough, but I understand what you're saying re to long exposures. I think that those who use other types of negs would be able to craft them for faster exposure times and hopefully eliminate the problem.

 

[Jim Fitzgerald]

Paul, very nice image! Bravo. I agree that one has to get the process dialed in so that one can cover all types of images with carbon. Crafting the negative for the process is key. Always a lot to explore and learn. This is what I love about this process. It keeps you thinking all of the time. I'd love to see the image you posted at some point. What was the exposure time in minutes?

Sorry, I meant to saw Andrew!

 

[Vaughn]

Hey Jim! Pour some tissues last night -- used x-ray film as the support. Easy to work with and in a few days I'll see how my system handles the thicker support! Thanks for the idea!

Beautiful image, Andrew! The clouds really add lift to the image!

Vaughn

 

[Jim Fitzgerald]

Vaughn, I love the "feel" of the x-ray film. A bit stiff during development when you go to peel it but It works great for me. Let me know how you like it.

 

[Vaughn]

I'll let you know, Jim! I was wondering how the peeling off of the tissue support will be. Not carbon related, but yesterday I developed a roll of 120 Agfa 25 that has been on my desk for awhile, and a roll of Tech pan that has been around for almost as long. The Agfa had images of my boys -- probably 7 years ago! What a fun discovery!

 

[Jim Fitzgerald]

Vaughn, I've got a dozen rolls of 120 I need to develop. Some are of my boys when they were in college and some of the others? I really need to develop them.

Takes some getting used to using the x-ray film as a tissue support but you can use it over and over