Carbon highlights "eaten out"

[gattu marrudu]

It is painful to read of your quest for highlight detail in con-tone carbon printing. While many will come forward with advice the sad truth is that carbon prints have a well-documented problem with the loss of highlights (see the 11-17-11 APUG Post: Highlight Loss in Carbon Printing) This can easily be seen when printing a step wedge, but most carbon enthusiasts print "pictures" and are satisfied with the results of their efforts.

Charles

I will include your link here for convenience: http://www.apug.org/forums/viewpost.php?p=1259943
Having that important information in mind, in my case I can change the way I want my prints to look. I moved to carbon from palladium with the specific goal of getting better shadow details, which Pd was giving me a hard time with. The prints are in low key and I can tone down the highlights without having the picture sell its soul to the devil.

Thanks!

[Vaughn]

I do not seem to have many problems with eaten out highlight when printing carbons from continous-tone negatives. Perhaps I have not noticed it. The one or two times I have noticed it it has been due to, or I have attributed it to, over-developed negatives.

The below might be of some limited help. I rephotographed a 8x10 carbon print with a digital camera and the quality of the reproduction is suspect.

The highlight section that is enlarged is out in the sun (on white granite), compared to the heavy shade of the foreground. There is detail in the highlights.

[banana_legs]

Hi Charles,

Yes I completely agree with you and the post you referred to that good highlight detail is always going to be an issue with carbon and con-tone negs. I have found however that it is possible to make the problem even worse if the receiving substrate is not well sized. The problem can also be worse if very high sugar concentrations are used in the glop; the gelatine layer is almost 'softer' then and more prone to washing away in development. I have also had more issues with thin, highly pigmented tissue, rather than thick tissues with low pigment concentrations, I have assumed being due to less gelatine being needed for the highly-pigmented case and so the highlight layer is very thin.


Best regards,

Evan

[gattu marrudu]

Hi Charles,

Yes I completely agree with you and the post you referred to that good highlight detail is always going to be an issue with carbon and con-tone negs. I have found however that it is possible to make the problem even worse if the receiving substrate is not well sized. The problem can also be worse if very high sugar concentrations are used in the glop; the gelatine layer is almost 'softer' then and more prone to washing away in development. I have also had more issues with thin, highly pigmented tissue, rather than thick tissues with low pigment concentrations, I have assumed being due to less gelatine being needed for the highly-pigmented case and so the highlight layer is very thin.


Best regards,

Evan

I was just thinking about that. So if instead of using B&S's tissue (which is great to start with, but thin and very concentrated in pigment AFAIK) I made my own glop, thicker and with less pigment, would that help?

The fact is that my highlights are REALLY bad sometimes, so I cannot really blame it completely on the tissue. I can't imagine B&S selling a tissue which yields such bad results for reasonably processed prints.

But, trying to rule out all other factors, I tried acidic mating bath, double hardened substrate gelatin, even fixed out silver photo paper. The highlights are still being washed off. So I will try brewing my own glop next.

[Vaughn]

Since I make my own tissue and I use the minimum amount of pigment, my highlights will actually be made of a thicker layer of gelatin than using a tissue with a much higher pigment amount. This is what could be protecting my highlights from being 'eaten out'.

I use 4 grams of lampblack watercolor paint (from tubes) to 750 ml water, 90 grams gelatin (food grade) and 60 grams sugar. Different brands of watercolor will contain different amounts of lampblack...so one needs to standardize on one brand if one goes that route.

[banana_legs]

Hi Gattu,

The temperature of the developing water can also have an effect too (quite a subtle effect, but sometimes noticeable); I recently did a run of 6 prints in quick succession and used the same developing water for them all. The water was in a tray sat on top of a water heater plate, which does not have good temperature control. Over the course of the prints, the 'blown highlight' regions around some lamps that were in the image got larger and larger, yet the shadow areas and rest of the image looked exactly the same. It took me a while to realise that it was the temperature of the developing bath that had been slowly increasing between the prints, making the print contrast just slightly higher for each successive print.

The first print was developed at 41 degrees and looked fine, the 5th at 47 degrees and much detail in the lamp area that was present on the first print was lost by the 5th print (I was floating the paper face-down to develop for 30 minutes). For the final print, I turned off the heater until the water had cooled to 40 degrees, then turned the heater back on during the development, giving a similar temperature profile to the first print. The result was that the first and the last print looked near identical, indicating that the exposure and sensitisation was consistent between prints too and only the temperature of development had varied for the others.

The negative was unusual for me in that it was a picture taken in a dark room with a few lamps that essentially were blown out in the print and did not have a good tonal range. I printed to capture the detail in the room and so knew the lamps would print white. It was the size of the 'halo' around the lamps which grew as the temperature of the water increased. I assume that the hotter water softened the gelatine more. On inspecting the print for 'correct development', I stopped the development when the bulk of the room looked right, rather than the highlights. Thus it was not as if the prints were overdeveloped as the rest of the image looked fine, rather the contrast of the image had changed.

Best regards,

Evan

[mark]

Pardon my ignorance but what does con-tone mean?

[Vaughn]

Continous-tone negatives (such as the ones we get from our cameras), as opposes to one made of dots for screen printing.

[Andrew O'Neill]

When I went to a higher pigmented tissue (16g per litre 9% glop), I found it challenging to preserve large, smooth areas of highlights, especially with digital negatives. Going back to 6g was much better. Are you using in-camera or digital negatives?

[gattu marrudu]

Are you using in-camera or digital negatives?

Neither one - I'm using 35mm TMZ mechanically enlarged to 7x10", which gives me quite some grain.

@Evan: I haven't felt the need to standardize development yet. Until I have to pull an edition, I can just lift the print and see what it looks like. My temperature goes over 40C sometimes, which might be destroying the thinner layers of gelatin.

Also, I noticed visible differences between supports treated differently (more or less sizing, one or two coats, more or less formalin). Hot-dog rolling leaves a relatively rough texture, which I am concerned might create micro-bubbles or weaker points during mating. So even if up to 10% concentration is suggested for gelatin, I prefer two coatings of 4% and roll until the gelatin starts to set and yields a finer texture.