Traditional or New Cyanotype?

[chris_rini1]

I don't have a darkroom yet, so I'm using cyanotype to make proofs of

my 120 negatives. The New Cyanotype process is said to have more

contrast range, but I've not tried it yet. Any suggestions? Thanks,

Chris

[silent1]

The traditional is about 1/10 the price (at least in kit form) of the new cyanotype -- that, is the traditional kit makes a liter of mixed sensitizer (500 ml of each solution); the Formulary new cyanotype kit makes 100 ml total.

 

I'm not certain about new, but with a suitable high contrast negative and no potassium dichromate, traditional can record seven steps of a 21 step tablet (which is about what you'd get from silver gelatin printing); with the dichromate to enhance contrast (and allow good prints from "normal" negatives), this range is reduced to only five steps.

 

Negatives need to be higher in contrast than would print comfortably with silver gelatin, or the self-masking (due to printing out as you expose) will flatten the print too much. My recent experience is that a normal negative prints pretty well with a single drop of the 1% dichromate solution in 2 ml of mixed sensitizer (for traditional chemistry from the Formulary kit -- just ferric ammonium citrate and potassium ferricyanide, no oxalic acid or other additions). I've had exposures running about five minutes in bright, direct, midday sun (early August, 47 degrees north), perhaps a little more exposure needed with contrast enhancer added.

[reinier_de_vlaam]

One of the advantages of the new process is that it is less toxic so easier to handle (still it is not drinkable ;-)). Have a look on Mike Ware's homepage about it...

 

http://www.mikeware.demon.co.uk/cyano.html

[silent1]

Beg to differ, Reinier, but the new cyanotype is *more* toxic than the traditional. Traditional is just ferric ammonium citrate, which has been used as a dietary supplement (supplies iron) and potassium ferricyanide which, though the name is scary, is less toxic than many modern B&W chemicals -- the cyanide groups (six of 'em) are tightly bound, and it takes a strong acid to break those bonds and release prussic acid. No, you shouldn't drink cyanotype solutions -- there's plenty of strong acid in your stomach -- but traditional cyanotyp is certainly no more hazardous than pyro developer or even Dektol (some people have severe reactions to metol).

 

Some newer formulae contain oxalic acid, which is very toxic (there's enough in a single rhubarb leaf to kill you), and the "new cyanotype" that stores as a single solution is more toxic yet.