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?

[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?

[Alan Townsend]

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?

The watercolor paper I buy at my Walmart (Grumbacher) works very well for cyanotype witthout any pre-treatments using a 20-10 fac-pfc sensitizer, although probably not very archival since it is heavy on the chalk content. Some people use a 1% citric acid solution as pre-treatment for some papers that don't give a very deep dmax, like Strathmore 300 series papers, which I have found need this. Any watercolor paper can be soaked in an about 1% hydrochloric acid solution overnight to completely remove all chalk. This makes the paper like a limp rag, and requires many washings to remove the acidity, but may help with long term permanence. Too much work in my book as well.

Most cheap watercolor papers work quite well for cyanotypes. Save the expensive ones for your art gallery debut. I'm 71 years young and believe my cyanotypes will last the rest of my life, although that not may be as long as yours.

I foam brush my blue prints with a 1% citric acid solution after exposure to oxidize and extend the tonal range a bit, a 10% vinegar solution will work similarly, then wash in water using a different foam brush over the surface using several water changes. Brushing the surface while washing or toning will greatly improve the effects, much like watshing anything with a sponge using friction is better than soaking only.

OP since you are very experienced with cyanotypes (I prefer the term blue print since they are not cyan) I don't suggest cheap watercolor paper for you, but you should certainly use fresh sensitizer chemestry, but am sure you know that already. My experience is that ferric ammonium citrate solution (20%) will keep for only a few months. It is a mineral supplment, a food, that bacteria and fungi just love. A drop of dish detergent may substitute for the tween.

Alan Townsend

[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.

[Jon Shiu]

what type of brush are you using?

[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!

[MichaelFS]

Thanks so much!

BTW- do you (or anyone on thread) recommend a good online source for Tween?

thanks again!