printing cyanotypes on hahnemuhle platinum rag (challenges)

[MichaelFS]

Hello all-

first time poster; a photographer friend highly recommended this forum.

I am a visual artist with a painting background working with cyanotypes for nearly 10 years, about 2/3 or more of that time working on canvas - which I've found to be more forgiving - and more recently on paper, particularly Arches Platine.
After struggling with what was probably a bad batch of Platine, I am trying to switch for the time being to hahnemuhle platinum rag, the 22" x 30" sheets.

I have printed a couple of sheets and am having lots of issues: splotching and lack of contrast, mainly.
I expose outside, and low UV levels have been part of the issue; the other issue is likely (possibly) due to coating process as well as the size and type of transparency I'm using:

i've been making hand-made transparencies, usually on Dura-lar drafting film, but in this case using Yupo paper, a white transluscent, synthetic paper. (https://yupousa.com/what-is-yupo/)
The size i'm using is roughly 22" square (about 21 3/4" by just over 22" specifically) so there's little margin from transparency to paper.

I'm attaching an image that has the hahnemuhle print on the left, and a print on Bee Mixed Media paper on the right for comparison- much better though still not ideal (https://www.jerrysartarama.com/bee-d...d-36inx5yd-808)

The feedback I've received from my contact at Bostick & Sullivan, where I've been buying supplies for years, is that (in lieu of using Tween), I should brush the paper with water, allow to be 80% dry, and then coat the paper with the cyanotype mixture (another contact there recommended 10% solution Ferrric Amon. Citrate and 10% Potassium Ferricyanide) to get a proper coating.

One last note is that I don't have any Tween in my studio, but am willing to get some if that's highly recommended, esp. based on my issues.

Thank you very much for reading and apologies if this it too long a post!

Michael

[Jon Shiu]

try this group?
https://www.facebook.com/groups/Alte...phicProcesses/

[jnantz]

I've never printed with yupo or on paper that large but I've gotten splotchy HPR, have you acidified your paper, how many coats of cyanotype chemistry are you doing, bone dry between coats?

[Jon Shiu]

what type of brush are you using?

[pigpen]

I'm very new to alternative processes so I'm hoping to learn as much here as the OP. Is it necessary to acidify your paper first? I've only been working with cheaper watercolor paper from walmart until I get better at the whole thing. I do have a pack of Arches and a pack of crazy expensive Hahnemuhle 100% cotton rag to experiment with. I thought that hahnemuhle was made special for this kind of thing, I don't remember watching any videos where they acidified the paper, especially hahnemuhle. Due you use oxalic acid or citrus acid?

[MichaelFS]

I've never printed with yupo or on paper that large but I've gotten splotchy HPR, have you acidified your paper, how many coats of cyanotype chemistry are you doing, bone dry between coats?

I have NOT acidified the paper.
I've been doing just one coat of the paper.

[MichaelFS]

Synthetic brush, 6" wide (I can show you the exact one if that would help; but don't believe brush is the issue)

[FotoD]

Using Tween *and* making sure HPR is humid enough is highly recommended.

Humidifying with steam 40s - 2min works. But with large papers brushing on distilled water can be easier. Wet the brush and brush on a thin even layer. Wait a couple of minutes until the surface is matte. Now you apply the emulsion.

4 drops of 10% Tween / ml emulsion should do it. But you can use more if it's not enough.

A soft synthetic brush helps avoiding brush marks.

Good luck!

[paulbarden]

I would suggest: try sizing the paper with Arrowroot size before applying the cyanotype sensitizer. Make sure the size is dry before applying the cyanotype, of course.

[jnantz]

I would suggest: try sizing the paper with Arrowroot size before applying the cyanotype sensitizer. Make sure the size is dry before applying the cyanotype, of course.

I was going to suggest the same thing after acidifying the paper ...