The sensitizer is a 5% working solution of ammonium dichromate mixed 50/50 with isopropyl alcohol. My standard is to apply 1ml of solution for ever 10 square inches of tissue. So, 4ml of dichromate solution and 4ml of isopropyl mixed for an 8x10. Sorry for the English measurements, but growing up in the US, I'm just used to thinking in terms of 8x10, 11x14 etc... The key point is that this is just a standard I have calibrated to, no and exact guideline. The amount of dichromate sensitizer applied and the exposure are the key factors in adjusting contrast. Many different combinations of tissues, sensitizers, and exposures can work. I also now use a foam roller for applying the sensitizer. It is much more reliable. These topics are also covered in greater detail in the book I wrote with Sandy King: www.johnlockhart.net/carbonbook
Thanks so much John, your explanations are really appreciated. I guess I will just convert your US measurements in the European ones for starting and then I will try to find my standard. I guess that it is all a matter of consistency... especially if I work with digital negatives... I still need to learn a lot about carbon transfer, I've just started and by far I have failed a lot. But I am sure I will find my way. About your book, I am really considering the idea of buying a copy: I have seen some preview of it somewhere and it looks so interesting. I am sure it will be very useful to me. It would be really cool if you or Sandy come to Italy for a workshop. It is also a wonderful Country to visit, you would be very welcome :-)
One more question (sorry): is the solution amount related to the tissue thickness? I mean, you use that amout for a 1mm glop? What if you have a 0,5mm glop? Do you need half dichromate or still the same amount?
what if i have only potassium dichromate? I don't use alcohol then?
You said 8ml of solution for (ho many?) square inches of tissue...? Sorry it's a bit hard to understand :-)
The sensitizer is a 5% working solution of ammonium dichromate mixed 50/50 with isopropyl alcohol. My standard is to apply 1ml of solution for ever 10 square inches of tissue. So, 4ml of dichromate solution and 4ml of isopropyl mixed for an 8x10. Sorry for the English measurements, but growing up in the US, I'm just used to thinking in terms of 8x10, 11x14 etc... The key point is that this is just a standard I have calibrated to, no and exact guideline. The amount of dichromate sensitizer applied and the exposure are the key factors in adjusting contrast. Many different combinations of tissues, sensitizers, and exposures can work. I also now use a foam roller for applying the sensitizer. It is much more reliable. These topics are also covered in greater detail in the book I wrote with Sandy King: www.johnlockhart.net/carbonbook
Thanks so much John, your explanations are really appreciated.
I guess I will just convert your US measurements in the European ones for starting and then I will try to find my standard. I guess that it is all a matter of consistency... especially if I work with digital negatives... I still need to learn a lot about carbon transfer, I've just started and by far I have failed a lot. But I am sure I will find my way.
About your book, I am really considering the idea of buying a copy: I have seen some preview of it somewhere and it looks so interesting. I am sure it will be very useful to me.
It would be really cool if you or Sandy come to Italy for a workshop. It is also a wonderful Country to visit, you would be very welcome :-)
One more question (sorry): is the solution amount related to the tissue thickness?
I mean, you use that amout for a 1mm glop? What if you have a 0,5mm glop? Do you need half dichromate or still the same amount?