post alternative techniques

[Ramiro Elena]

Beautiful tone and gradation. I need to try that formula!

[Colin Graham]

4x5 TMX contact print, ferric ammonium oxalate cyanotype. Schneider 75/8. TMX is a b*tch to contact print due to its UV blocking base, so printing times are quite long: I think this was 9 minutes at a distance of about an inch with a 50W face tanner unit. Other negatives (both printed and real ones) take about 2-3 minutes at a distance of 8 inches, so the difference is quite a few stops.

Are you using Mike Ware's formula? I used to get quite a speed bump by diluting Ware's with 40% citric acid. It's mainly intended to help the solution work on a broader range of 'impure' papers, but it also helped me cut exposures quite a bit as well on Fabriano EW, Arches, and BFK Rives. At high dilutions such as 1:1 it does result in a color shift from that rich prussian blue to a traditional cyan, or at least it did for me on these papers.

[koraks]

Yes, I am, that's to say: I only add the dichromate when mixing the sensitizer, currently one drop of 2% per ml of sensitizer. I also add 40% citric acid, but also a single drop per ml. I'll try increasing the amount of citric acid and see what happens. Btw, the mixture as it is now already prints 2 to 3 times as fast as traditional cyanotype with a much longer tonal scale. But I'm not quite happy yet with the dmax.

[Colin Graham]

I mostly used Ware's for tri-color and cyan-palladium processes, so the softer contrast and the traditional cyan hue were useful for that. At high citric acid levels the Ware's does lose some of its richness.

[Vaughn]

4x5 TMX contact print, ferric ammonium oxalate cyanotype. Schneider 75/8. TMX is a b*tch to contact print due to its UV blocking base, so printing times are quite long: I think this was 9 minutes at a distance of about an inch with a 50W face tanner unit. Other negatives (both printed and real ones) take about 2-3 minutes at a distance of 8 inches, so the difference is quite a few stops.

The long exposure probably helps with the tonality -- the printing-out image has time to form and do its self-masking thing. Also, the exposure times do not change much by moving the light closer...the inverse square law does not apply as strongly at short distances with diffuse light sources and lights in reflectors.

[koraks]

I'm going to do some more experimenting today; I'm not wrote sure how the levels of dichromate and citric acid work in practice, so I'll have to figure it out so I can adjust the process to match different negatives - insofar that's possible.

Vaughn, you're right; it isn't exactly a square relationship. However, distance is a parameter I use all the time to vary exposure (in addition to time obviously). So far, this has allowed me to fit all exposures for the processes I use in a 2 to 10 minute frame, which is quite convenient!

[Will S]

Bromoil from contact print 8x10 - David Lewis paper. My daughter as Isaac Newton in a GB Shaw play.

[Monty McCutchen]

Will that is very nice. What a great process to add to the memory of your daughters experience and role in the play. Really well done

Monty

[Colin Graham]

I'm going to do some more experimenting today; I'm not wrote sure how the levels of dichromate and citric acid work in practice, so I'll have to figure it out so I can adjust the process to match different negatives - insofar that's possible.

Dichromate increases print contrast, citric acid decreases it.
Supposedly, with adjustments, Ware's can handle a negative DR of up to 2.6- but I'm just quoting from the link provided earlier.

[koraks]

@Will: I agree with Monty: well done in every respect!

Colin, that's exactly as how I understand it. But I'll need to experiment to get a feel for what's what. I don't have a densitometer, so I can only rely on visual inspection and experimentation. I just tried some prints with only a drop of 40% citric acid and no dichromate added to the mix and they came out quite bland. Dmax is lacking and contrast is low. I'm currently drying a few papers with the opposite mix: 3 drops of 2% dichromate per ml of solution (went overboard a bit!) and no citric acid. Let's see how it works out.