U of S | Mailing List Archive | alt-photo-process-l | Clearing cyanotypes, minimizing bleeding into highlights

Clearing cyanotypes, minimizing bleeding into highlights

Hi. My first post - and its a basic one.  I've been wading through the
archives and searching and reading all my references and I'm somewhat

The only thing holding me back from doing cyanotypes is the
difficulties in clearing the print without blue bleeding into the
highlights.  I cannot maintain paper white.  I've been using the PDN
system to calibrate my exposures (been playing with Pd, POP, Silver -
cyanotypes keep driving me back to Pd printing). Mark Nelson made some
suggestions and I combined with some reading and interpolation and am

- Traditional Cyanotype (Bostick and Sullivan kit).
        3:2 mix (A:B) - to increase speed. Two drops Tween 20
        per 10ml emulsion.

- Humidity is 50-60% in room - paper left out for at least
        1/2 hour to stabilize.

- Brush coat (hake brush), work emulsion to paper to get a 
        consistent layer with fairly gentle strokes

- Air dry about 2 hours (I know, I know - Mark keeps telling
        me to be consistent - I watch a movie during drying).

- Been focusing on Crane's Diploma Parchment from B&S - 
	calibrate to a 2m 56s exposure using 31 step tablet and X-rite
	810 (I think) densitometer. (Diploma Parchment has
	much better wet strength than Crane's Platinotype
	had it seems to me)

- Dmax 1.29+ (partly because I am not using hydrogen peroxide 
        any more as I think it aggravated the bleeding into
        the highlight areas). And 21 steps of scale.

- Mark passed on Sam Wang's (?) suggestion to clear the exposed
	paper inverted in a water bath. I add about 5 ml of a 1:100
	dilution of Hydrochloric Acid to about 2 liters of clearing
	bath to start.

- I run water into the bath slowly to allow the water to change out
	the blue and keep it up until it remains clear (about 
	1/2 hour).  No hot water - so tap water circulating is about 
	50 deg F at this point?  (don't have the Ph of my water - 

- Remove print, lay on paper towel - lay another sheet of paper
towel on top - remove excess water, dry flat face up.

I'm wondering if I am asking too much from the process?

Any words of advice?

Mark suggested someone had success with Arches Platine - which
I had some of and I gave it a whirl - the paper is slower with
the same steps above - by 1 stop or more?


Thanks:-) And Happy New Year!