Paul
Member
Hi,
I have a question about contrast control with the kallitype process. I know it has been discussed here in passing, but I am still a little confused. When I first began making kallitypes, I followed Sandy Kings excellent article posted on unblinkingeye.com. I believe there is some mention of the ability to control contrast in the article, but he does not elaborate. He recommends a negative with a DR of 1.8. Makes sense.
I recently stumbled on another version of this article at alternativephotography.com where contrast control with the addition of potassium dichromate is discussed in greater detail:
Contrast can be controlled by the addition to the developer of a few ml of a 5% solution of potassium dichromate solution. The practical limit ranges from as little as 1 ml per liter of developer up to about 16 ml per liter. This allows the use of negatives from a DR as low as about 1.2 to a maximum of about 2.2. If too much dichromate is added, printing times will increase considerably and the image will take on a granular look. For negatives that have been developed to a DR of about 1.8 add about 2ml of the 5% potassium dichromate per liter of developer.
[After posting, I noticed that this paragraph appears in both articles, but I only see the recommendation for 2 ml with a 1.8 DR in the alternativephotography.com article.]
What I am wondering is this:
I was under the impression that a negative with a DR of 1.8 was appropriate for use with straight sodium citrate developer with no contrast agent additions. If it is recommended that one add 2 ml of potassium dichromate when using a negative developed to a DR of 1.8, does this mean that with straight developer a kallitype requires an even denser negative? Is this what is meant by a maximum of 2.2? In other words, shoot for DR of 1.8 with 2 ml of potassium dichromate, but if you miss that target and overdevelop you can skip the dichromate; and, if your negative is too thin, you can add more dichromate?
And last, but not least: does anyone have the DR numbers for a given quantity of dichromate per liter of developer, or is there a certain amount of trial and error with this?
Thanks,
Paul
I have a question about contrast control with the kallitype process. I know it has been discussed here in passing, but I am still a little confused. When I first began making kallitypes, I followed Sandy Kings excellent article posted on unblinkingeye.com. I believe there is some mention of the ability to control contrast in the article, but he does not elaborate. He recommends a negative with a DR of 1.8. Makes sense.
I recently stumbled on another version of this article at alternativephotography.com where contrast control with the addition of potassium dichromate is discussed in greater detail:
Contrast can be controlled by the addition to the developer of a few ml of a 5% solution of potassium dichromate solution. The practical limit ranges from as little as 1 ml per liter of developer up to about 16 ml per liter. This allows the use of negatives from a DR as low as about 1.2 to a maximum of about 2.2. If too much dichromate is added, printing times will increase considerably and the image will take on a granular look. For negatives that have been developed to a DR of about 1.8 add about 2ml of the 5% potassium dichromate per liter of developer.
[After posting, I noticed that this paragraph appears in both articles, but I only see the recommendation for 2 ml with a 1.8 DR in the alternativephotography.com article.]
What I am wondering is this:
I was under the impression that a negative with a DR of 1.8 was appropriate for use with straight sodium citrate developer with no contrast agent additions. If it is recommended that one add 2 ml of potassium dichromate when using a negative developed to a DR of 1.8, does this mean that with straight developer a kallitype requires an even denser negative? Is this what is meant by a maximum of 2.2? In other words, shoot for DR of 1.8 with 2 ml of potassium dichromate, but if you miss that target and overdevelop you can skip the dichromate; and, if your negative is too thin, you can add more dichromate?
And last, but not least: does anyone have the DR numbers for a given quantity of dichromate per liter of developer, or is there a certain amount of trial and error with this?
Thanks,
Paul
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