Cyanotype Blotchiness

Greetings,

I've been making cyanotypes for a year now, but have recently encountered an issue that I was hoping to get a second opinion on. I'm encountering erratic blotchiness where there should be no emulsion following development. The attached image shows three versions of the same print using virtually the same procedure. In each case I did a long exposure (images 1 & 2 were exposed at 2.25 hours, while image 3 was exposed at one hour).

I've exposed prints for long periods before, and made entire an photo series having never encountered a problem like this one. The highlights in previous prints have been clean and white, and this a new issue that has cropped in the last month and a half. I coated each of these prints with chemistry using the same brushing technique (painting horizontally and vertically twice over) as previous prints, and I haven't made any changed to my light box. In the attached example I used the same transparency for each print as well.

I'm thinking my chemistry might be the culprit, because the purple blotchiness has been inconsistent from print to print while the rest of the procedure has been consistent. I've started to use a coffee filter on my Solution A to remove mold thinking that might be the cause, but that hasn't resolved it.

It could be that I didn't fully seal one of my solution containers and allowed some kind of reaction with heat and/or moisture from a nearby dishwasher that sits next to the cabinet where I was previously storing my chemicals. I've since moved the storage site of the chemistry.

If anyone has any thoughts on other potential causes, I'd be very glad to get other ideas to make sure I've tried everything. I've ordered new chemicals just in case, but would like to avoid wasting more paper or chemistry in case it's being caused by something else.

Thanks for your consideration and ideas.

All the best,
Dan

I can't say if chemistry is or is-not your issue, but also consider the paper you are using and the sizing method you are using.

Thanks Brian for your thoughts. The paper is an interesting point, but I've used the same paper over the last year and am now only encountering this issue.

You mentioned mold in your solution. Did you use any preservative to stop mold growth?
It might be pigment stain, with mold growth in time your ferric solution might have ferrous impurities.
When you mix B into solution A, do you observe any blue colored formation?

The only time I have ever seen a colour like that (assuming your scans are accurate in hue) on one of my cyanotypes is when I've bleached one with ammonia prior to toning.

Now ... paper. Just because you have used the same brand of paper for a year doesn't mean that the paper has not changed. Paper manufacturers sometimes change their methods, materials, sizing and so on.
So, the paper could potentially be a culprit.

If you size your paper, do consider whether you have changed the size or whether your size may have become contaminated.

Contaminated chemicals are also a possibility. Why not make up a fresh batch, using DI or distilled water, and test again?

Contaminated water from the tap, stray chemicals in your trays. Maybe there;s been a change of composition in your tapwater? (Perfectly possible, you only have to think of what happened in Flint)

Troubleshooting a problem like this means keeping an open mind and eliminating things iteratively. Don't change two things at once, just one thing at a time, and eventually you'll hit the solution.


Good luck

Herzeleid said:

You mentioned mold in your solution. Did you use any preservative to stop mold growth?
It might be pigment stain, with mold growth in time your ferric solution might have ferrous impurities.
When you mix B into solution A, do you observe any blue colored formation?

Click to expand...

Herzeleid,

I did not use any preservative for mold growth. I was just using a coffee filter on Solution A before using it. I recently thought I saw mold in Solution B, so I used a coffee filter on that too, but then I learned that I was filtering out the salts in Solution B (or at least I think that's what happened), which caused the print just to develop into a water-soluble yellow (not cyanotype). Perhaps there are impurities in Solution B. I'm not sure I saw blue colored formation, but I'll look for it.

pdeeh said:

The only time I have ever seen a colour like that (assuming your scans are accurate in hue) on one of my cyanotypes is when I've bleached one with ammonia prior to toning.

Now ... paper. Just because you have used the same brand of paper for a year doesn't mean that the paper has not changed. Paper manufacturers sometimes change their methods, materials, sizing and so on.
So, the paper could potentially be a culprit.

If you size your paper, do consider whether you have changed the size or whether your size may have become contaminated.

Contaminated chemicals are also a possibility. Why not make up a fresh batch, using DI or distilled water, and test again?

Contaminated water from the tap, stray chemicals in your trays. Maybe there;s been a change of composition in your tapwater? (Perfectly possible, you only have to think of what happened in Flint)

Troubleshooting a problem like this means keeping an open mind and eliminating things iteratively. Don't change two things at once, just one thing at a time, and eventually you'll hit the solution.


Good luck

Click to expand...

pdeeh,

I like the overall colors and hue, just not the inconsistent purple "bruises" that add a grainy quality with unplanned hues into the print, both in the highlights and shadows.

That's an interesting point on paper. I'm using Strathmore 400 watercolor paper, but I guess I hadn't considered they may have changed their paper over time. I don't typically size my paper.

I think I will take your advice and start with fresh Solutions A and B. You're right, it's better to take an iterative approach adjusting only one variable at a time.

danhendrickson said:

Herzeleid,

I did not use any preservative for mold growth. I was just using a coffee filter on Solution A before using it. I recently thought I saw mold in Solution B, so I used a coffee filter on that too, but then I learned that I was filtering out the salts in Solution B (or at least I think that's what happened), which caused the print just to develop into a water-soluble yellow (not cyanotype). Perhaps there are impurities in Solution B. I'm not sure I saw blue colored formation, but I'll look for it.

Click to expand...

Ammonium ferric citrate solution is prone to mold adding some thymol or sodium benzoate will stop it. I have never observed mold or precipitate in potassium ferricyanide solution. I never felt the need to filter any of the solutions. If that is the case, you might have contaminated solutions.

Regards
Serdar

Herzeleid said:

Ammonium ferric citrate solution is prone to mold adding some thymol or sodium benzoate will stop it. I have never observed mold or precipitate in potassium ferricyanide solution. I never felt the need to filter any of the solutions. If that is the case, you might have contaminated solutions.

Regards
Serdar

Click to expand...

Thanks for this information. I'm going to take a deeper look at both solutions to see if I observe anything.

I should also mention that after I expose the print, I've noticed some unevenness in the coloration before I've applied water to develop the print. This unevenness has been atypical of past prints when they were coming out as planned. That also suggested to me contamination of the chemistry rather than the water I use to develop the print.

danhendrickson said:

the inconsistent purple "bruises"

Click to expand...

yes that's exactly what I was referring to

I have only seen that color when the paper was not sufficiently dry after coating. Otherwise, I have no other clues.

Could it be that it's been muggier lately? Have they been drying sufficiently before exposing?

Mix up fresh chemistry.

Vaughn said:

I have only seen that color when the paper was not sufficiently dry after coating. Otherwise, I have no other clues.

Click to expand...

This solved it. Over time I must have gotten sloppy and not made sure each print was 100% dry. Last night I did a new run of prints using all the same paper, water, chemistry, etc, but this time used a hairdryer to make sure each page was bone dry before exposing it in the light box. The prints now come out perfectly, with no blotchiness.

Thanks everyone for all your ideas, discussion, and help!

danhendrickson said:

This solved it. Over time I must have gotten sloppy and not made sure each print was 100% dry. Last night I did a new run of prints using all the same paper, water, chemistry, etc, but this time used a hairdryer to make sure each page was bone dry before exposing it in the light box. The prints now come out perfectly, with no blotchiness.

Thanks everyone for all your ideas, discussion, and help!

Click to expand...

Uneven humidity after drying might cause uneven densities in the print. But purple color is still odd.

I dry my papers for 20 mins before printing, never used hairdryer. I always put a clear mylar between the paper and the negative, because I have damaged a few negatives before.
I did prints at relative humidity %75, I even added glycerin to see if moisture helps speed up printing speed in cyanotype.

IMO, something else is also going on, but I hope drying before printing helps to prevent this problem.