Carbon printing and bubbles

[sanking]

I would recommend working out your transfer procedures with RC silver papers as they are about as reliable as it gets for carbon transfer. If you can not make a good transfer on RC silver papers something in the methodology is way off.

Soak time is dependent on several factors, including water temperature, the percentage of the glop, sugar loading, and coating thickness. In my work, which is primarily with tissue made with a 10% gelatin (250 Bloom gelatin) solution, with 0.5% sugar, and poured to a wet height of about 1.0 mm, I soak the sensitized and exposed tissue for about three minutes in the summer in water at about 72º F, and four minutes in the winter in water at about 66º F. My experience is that too short of a soak can be as bad as soaking too long.

Sandy

[Jim Fitzgerald]

The interesting thing about carbon printing is the variables. Where I live by the beach, my soak time is short in comparison to what Sandy does in his work flow.
Generally my results are consistent. No bubbles. I think the temp of the development water is a problem.

Take Sandy's advice and use RC paper for the transfer. Most of all establish a repeatable work flow and beware of "Cycles of the Moon"

[John Jarosz]

My experience is that too short of a soak can be as bad as soaking too long.

I have always felt this is true, but I have no hard data to confirm it.

+1 on the "Cycles of the Moon".

[sanking]

I have always felt this is true, but I have no hard data to confirm it.

+1 on the "Cycles of the Moon".

Yes, it is easy to advise that soaking too short is as bad as soaking too long, but that begs the question what is long enough. As Jim suggests, we can really only learn from a consistent work flow where all of the important parameters are identical (or as similar as possible).

That said, the major determinants in soak time are, 1) tissue coating thickness, and 2) amount of plasticizer (sugar) and/or humectants (glycerine) added to the pigmented gelatin solution, and 3) temperature and time of the soak bath. Each can have a major impact on how fast the tissue absorbs water in the mating bath.

One of the characteristics of carbon printers is that are by nature inclined to experimentation for its own sake so they tend to not listen to the advice of others and set out on their own personal adventure in formulating the pigmented gelatin solution, and in pouring and sensitizing it. This creates a condition akin to chaos in terms of a common approach, which is good in that we are all right every now and then, and can always blame our failures on events beyond our control!!

But there is truly something awesome about the elegance of the process, and at heart its basic simplicity. It is sad that many photographers will die having never made a good carbon print, or worse, never even seeing one.

Sandy

[Jim Fitzgerald]

Yes, it is easy to advise that soaking too short is as bad as soaking too long, but that begs the question what is long enough. As Jim suggests, we can really only learn from a consistent work flow where all of the important parameters are identical (or as similar as possible).

That said, the major determinants in soak time are, 1) tissue coating thickness, and 2) amount of plasticizer (sugar) and/or humectants (glycerine) added to the pigmented gelatin solution, and 3) temperature and time of the soak bath. Each can have a major impact on how fast the tissue absorbs water in the mating bath.

One of the characteristics of carbon printers is that are by nature inclined to experimentation for its own sake so they tend to not listen to the advice of others and set out on their own personal adventure in formulating the pigmented gelatin solution, and in pouring and sensitizing it. This creates a condition akin to chaos in terms of a common approach, which is good in that we are all right every now and then, and can always blame our failures on events beyond our control!!

But there is truly something awesome about the elegance of the process, and at heart its basic simplicity. It is sad that many photographers will die having never made a good carbon print, or worse, never even seeing one.

Sandy

Sandy, I could not agree more. I knew from the moment I saw first carbon print what my destiny was as a photographer. How great is that! Seeing a great carbon print is something special. Making one is heaven.

[brucep]

No, just me interchanging sugar and glucose incorrectly. It is definitely common old sugar.

Interestingly, in the book Photography Theory and Practice by Clerc, he actually uses a mixture of Loaf Sugar (which I believe to be the same as granulated) and Glucose syrup, so using Glucose must have some positive benefit unless it used to be much cheaper than loaf sugar and you could get away with using some to save money.

Bruce

[Jim Fitzgerald]

The advice I give all of my students is follow my directions and don't ask why. Learn my established procedures. Once you have control of the mechanics of the process you can start asking questions why? The what if's come later after you can transfer and make beautiful prints all the time.

[brucep]

My comment was in response to Sandy's comment about not knowing what effect using glucose would have on the process rather than planning to try it.

I would say though, that without understanding as much as I can about the process I would be making wild changes to troubleshoot problems rather than targeted changes based on logical reasoning.

Anyhow, the same book I quoted above recommends mating at room temp if the room cannot be kept at 65°F to stop the formation of micro bubbles as the water warms up, and to soak the tissue until it stops having any tendency to curl. Just tried this, which was a 3min soak at 22°c and a perfect transfer with no lumps or holes😀.

Very happy.

Bruce

[sanking]

Interestingly, in the book Photography Theory and Practice by Clerc, he actually uses a mixture of Loaf Sugar (which I believe to be the same as granulated) and Glucose syrup, so using Glucose must have some positive benefit unless it used to be much cheaper than loaf sugar and you could get away with using some to save money.

Bruce

People have experimented with dozens of plasticizer type substitutions for cane sugar, from karo to molasses to sorbitol. None work any better than sugar, so why bother since pure cane sugar is one of the most commonly available substances on the planet, and *any* substitution in a pigmented gelatin solution can result in unexpected results. People in very arid climates (less than 25% RH) may also need a humectant in the pigment, and for that glycerine is as good as any. Where I live the RH rarely goes below 30% RH, and any glycerine added to the glop is more of a nuisance than help.

Did I mention that *any* substitution in a pigmented gelatin solution can result in unexpected results?

Sandy

[sanking]

Anyhow, the same book I quoted above recommends mating at room temp if the room cannot be kept at 65°F to stop the formation of micro bubbles as the water warms up, and to soak the tissue until it stops having any tendency to curl. Just tried this, which was a 3min soak at 22°c and a perfect transfer with no lumps or holes��.

Very happy.

Bruce

Congratulations on the good transfer. I used to believe that more than two minutes at 72º F was too long for the mating bath. However, I have come to understand that many of the problems we experience in transfer are due to dichromate degassing, which is alleviated by a fairly long soak.


Sandy