Carbon - spots on my print & negative

R Shaffer · May 31, 2011

Hi All,

Got a problem I can't figure out. Prior to printing there are no spots on the negative. After printing there are spots on the negative & print. See attached.

I'm spirit sensitizing with acetone and allowing the tissue to dry for 4 hours, no fan.

Any ideas? Are the tissues just not dry?

I don't see this in the body of the print, but it is quite evident in the step wedge at the bottom. I am getting a bit of blistering, but I think I just need to use dead water. These are digital negs.

pschwart · May 31, 2011

put negatives in a polypropylene bag before printing (Crystal Clear is one brand).

R Shaffer said:
Hi All,

Got a problem I can't figure out. Prior to printing there are no spots on the negative. After printing there are spots on the negative & print. See attached.

I'm spirit sensitizing with acetone and allowing the tissue to dry for 4 hours, no fan.

Any ideas? Are the tissues just not dry?

I don't see this in the body of the print, but it is quite evident in the step wedge at the bottom. I am getting a bit of blistering, but I think I just need to use dead water. These are digital negs.

R Shaffer · May 31, 2011

pschwart said:
put negatives in a polypropylene bag before printing (Crystal Clear is one brand).

How much will that effect the sharpness?

I want these to be sharp with lots of very fine detail. I am getting that right now. When I tried printing with the negative backwards I lost far too much detail.

Also I have a pad of Grafix .005" plastic film. Would that work the same?

pschwart · May 31, 2011

You won't see the difference with 2mil bags. Losing negatives is an unacceptable risk, and the bags are a great way to store negatives. I think 5mil plastic film is too thick, and the bags are more convenient, anyway.

R Shaffer said:
How much will that effect the sharpness?

I want these to be sharp with lots of very fine detail. I am getting that right now. When I tried printing with the negative backwards I lost far too much detail.

Also I have a pad of Grafix .005" plastic film. Would that work the same?

gmikol · May 31, 2011

Looks like your tissue is not dry enough (or alternately, you're using too high a vacuum if you're using a plate burner.) I had this exact same thing happen to me a while back, and it was due to tissues I had hurried through the drying process. You'll note that the spots on your negative are white, and on the print they're black, meaning that the ink has transferred from the OHP to the gelatin.

4 hours seems like it should have been plenty of time to try. I typically do 1.5-2 hours, and the ones I rushed and found problems on was only 1 hour (plus too much glycerin).

Good luck.

--Greg

R Shaffer · May 31, 2011

Thanks Philip,

I ordered the bags as I think your right the 5mil is too thick. Bags were cheap, but the shipping was kinda pricey. Slightly more than the 100 bags.

Thanks Greg,

I'm gonna try hitting the tissue with the hair dryer just prior to printing and see if that helps, otherwise, the bags are on the way. The ink transferring to the tissue makes a ton-o-sense and I would not have thought of that.

pschwart · May 31, 2011

try Jerry's or one of the other art supply sites. They will all have an equivalent product and shipping is usually reasonable. Sometimes they don't specify the thickness so you will need to ask.

gmikol · May 31, 2011

Are you using a NuArc? Maybe just open up the bleeder valve a bit? Mine doesn't have a vacuum gauge, but the 26-1k models do. I've read a recommendation of 5-7 inches of vacuum only (full atmospheric pressure being almost 30), so it doesn't suck the water out of the tissue.

Retro-fitting a vacuum gauge to my NL22 is on my to-do list for the summer.

You've already ordered clear bags, but I use Print-File fold-lock mylar negative pages and just cut the fold-lock flap off and use it for printing until it gets too banged up, then just chuck it.

--Greg

R Shaffer · Jun 1, 2011

It was only $13 for 100 crystal clear bags big enough for 11 x 14 negatives and another $13 for UPS ground shipping. It seemed a bit much however, they got them into UPS yesterday and I will have them today. That's pretty impressive service.

I wish I had a plate burner with vacuum frame. I keep checking craigslist,even ebay, but nothing ever comes up within driving distance.

John Lockhart · Jun 1, 2011

I agree with the diagnosis. Too much pressure from the vacuum caused blotched prints for me and, if my tissue was not dry enough it would definitely strip the ink from the film if I was not layering it with acetate.

I like the plastic bag idea. I have grown tired of cutting and taping acetate to every negative and typing to keep it spotless. I have also thought of trying a layer of saran wrap that could just be discarded easily for each print.

I have an NL-22 as well and the only thing I don't like about it is the lack of a vacuum gage. I now leave the bleeder valve wide open and get sharp prints, but I would like to have a gage to be able to get a more precise amount of suction. Any advice on selecting and installing a vacuum gage on one of these would be appreciated.

- JRL

R Shaffer · Jun 1, 2011

My first crystal clear bagged print is up and drying. Looks absolutely fantastic, no spots, no frilling and it held on to all the detail & sharpness I had without the bag. It's just perfect!!

I'll give it a closer inspection after it dries, but it is by far my best carbon print. It is print #1 in a new series of Antelope Canyon prints. It's been a lot of work getting to this point, getting my basic carbon curve, trying different pigments, having issues with blisters & frilling.....

But I'm jazzed right now. Time to make a big bad new batch of glop so I can pour tissues in the morning.

Can't help with your vacuum gage John, but the bags Philip recommended are great. Much thinner than I expected and a huge variety of sizes.

Thanks for all the help!!

John Lockhart · Jun 2, 2011

That's very good to hear. I despise taping acetate to my digital negatives and have ruminated quite a bit on a better way to do it. While I wait to get some bags I may also try the saran wrap idea this weekend.

I also recently made a really cool portable tissue making jig for the magnetic sign material method. It cost me 30 dollars and worked very well for me the first ime last weekend. I will post up a photo soon.

- JRL

Carbon - spots on my print & negative

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