yellow staining in cyanotype highlights

[Markkent91]

Hi all,

This week I have been experiencing yellow staining in my cyanotypes. When I wash the cyanotype after exposure, I have recently noticed this week that the yellow sensitiser is very stubborn and does not wash out completely in the highlgihts. the large areas of yellow do eventually fade somewhat but small little patches of yellow still remain. This is in contrast to the ones i was making last week where I have had no issues with this and in the first 30 seconds washing of these ones, the yellow would be gone. Now even after hours of washing, yellow remains.

I have kept my process the same as usual: same paper, same water tap, new solution, same acetate negatives. This week the weather has been very humid and so the darkroom may be warmer than usual..could this effect the coated paper while it is drying? It is strange because this has only started to happen.

 

[Sirius Glass]

Would you show us examples?

 

[Markkent91]

Would you show us examples?

Unfortunately I don't have them with me at the moment. I do have a pictue of this one I made last week that was fine - this the same image I have been trying to duplicate this week . Try to Imagine the highlights of the background /sky stained yellow. Oddly, the highlights in the detail of the foreground don't stain as much as the sky / wash out much easier.

 

[Herzeleid]

What is the amount of sensitizer you use per cm square? Is this the traditional cyanotype formula?
Can you give details on your process?

 

[Markkent91]

What is the amount of sensitizer you use per cm square? Is this the traditional cyanotype formula?
Can you give details on your process?

yes traditional formula. I do not use any other chemicals or washes ( citric acid baths, peroxide etc). My coating method with a brush can be a little uneven
at times ( a few missed spots here and there) but over the last three months, I have never had this issue. I thought perhaps i was coating too much emulsion on the paper, so i used less on the brush for a thinner coating - no difference, still staining.

I will be continuing cyanotypes tomorrow so will take some photographs of the cyanotypes I produce and post them here. Any guesses so far what the problem might be?

 

[Herzeleid]

Do you control how much sensitizer you use per cm square? Common approach is 1.5ml per 8x10inch (20x25cm) print area. So that is 0.75 A and 0.75 B solutions, but that amount can be effected by the brush you use and the thickness of paper.

Edit: 8x10"

 

[pdeeh]

I do not use any other chemicals or washes ( citric acid baths, peroxide etc).

I suggest you try a very mild Citric acid first wash - half a teaspoon in 2L of water is what I use.

Why? Because Citric acid has the property of being a siderophore - that is, it combines with iron very readily and forms water-soluble complexes.

As a result, any process that requires iron-bearing salts to be washed out after printing-out (cyanotypes, VDB, Namias' sepia for instance) will benefit by washing out faster and more completely.

(As an example, when I make a Namias' sepia, if I wash in running tap water, it takes about twenty minutes to clear the paper of remaining visible sensitiser; Two consecutive washes of 90sec in 300ml of Citric acid solution clears the paper completely).

The very oldest texts on making cyanotypes mention Citric acid washes, so there's nothing "modern" about this, in case you're concerned about authenticity of process.

 

[Markkent91]

Do you control how much sensitizer you use per cm square? Common approach is 1.5ml per 8x10inch (20x25cm) print area. So that is 0.75 A and 0.75 B solutions, but that amount can be effected by the brush you use and the thickness of paper.

Edit: 8x10"

I do yes.I use a hake brush as the hairs are soft and do not damage the paper fibers.

 

[Markkent91]

Here are a couple of images of the issue. Sorry for low quality, I can't upload high mb images.

 

[Markkent91]

I suggest you try a very mild Citric acid first wash - half a teaspoon in 2L of water is what I use.

Why? Because Citric acid has the property of being a siderophore - that is, it combines with iron very readily and forms water-soluble complexes.

As a result, any process that requires iron-bearing salts to be washed out after printing-out (cyanotypes, VDB, Namias' sepia for instance) will benefit by washing out faster and more completely.

(As an example, when I make a Namias' sepia, if I wash in running tap water, it takes about twenty minutes to clear the paper of remaining visible sensitiser; Two consecutive washes of 90sec in 300ml of Citric acid solution clears the paper completely).

The very oldest texts on making cyanotypes mention Citric acid washes, so there's nothing "modern" about this, in case you're concerned about authenticity of process.

I will certainly give it a try and see what the results are. Would a couple of drops of lemon juice do the trick? how long should the print be washed in the acid bath for?

 

[nmp]

Could be that the tap water quality (pH) changed recently. Alkaline water will hydrolyze iron salts to Fe(III) hydroxide which is an insoluble orange compound, hard to get rid of. Citric acid would be an insurance against that in addition to the aid in washing out as pdeeh explained.

 

[Markkent91]

Could be that the tap water quality (pH) changed recently. Alkaline water will hydrolyze iron salts to Fe(III) hydroxide which is an insoluble orange compound, hard to get rid of. Citric acid would be an insurance against that in addition to the aid in washing out as pdeeh explained.

Possibly, might explain why this problem has arisen suddenly. How long should i wash the cyanotype for in the first wash of lemon juice?

 

[pdeeh]

I will certainly give it a try and see what the results are. Would a couple of drops of lemon juice do the trick? how long should the print be washed in the acid bath for?

As mentioned, I do two initial washes, of 90 seconds each, both baths fresh. I don't reuse.
Lemon juice is (according to the the Blessed Wiki) ~5% citric acid.
I have no idea how that racks up against my extremely scientific measure of ½tsp/2L.

Really, the best way is to give it a try. If I were doing it I'd use about a teaspoon in a litre. But that's just me.

Don't forget that lemons are also full of sugars and other fruity stuff, including Ascorbic acid, so if you get unwanted results, then it's time to head to eBay for a few hundred grammes of the real thing.

 

[pdeeh]

Sigh.
Couldn't leave it there, been to the kitchen and weighed half a teaspoon of anhydrous Citric acid :/

For all intents and purposes, it's about 2g (depending on how shaky my hand is on the day), so that makes the solution about 1g/L, or a 0.1% solution.

If lemon juice is ~5%, then you'll need 20ml of juice and 980ml of water for the same.

Anna Atkins never worried about this you know

(as for "Why has it changed?" - well, paper can change batch to batch, tap water rarely changes much but you can get the typical composition from your local water supplier's website, the amount of sensitiser changes - we just can't help that, we make little mistakes or variances when we make up the chems, and most of all, humidity changes, which will change the absorption of the paper as well as how fully it dries after sensitising - it's been really humid in my neck of the woods this past few days, whereas it was really hot and dry 10 days ago.
My recommendation?
Embrace serendipity.)

 

[Markkent91]

Hello all,

Just a quick update. Still having the problems with the staining. Tried some lemon juice but that made no difference. However, I then proceeded to experiment using stopbath chemicals for conventional developing and it worked a treat! Of course, the staining onbly existed in the large highlight areas so I carefully applied the stop to areas effected using a hake brush and then washed away the stop with tap water. I am still curious as to why this happened ( I like to solve problems!) but with a deadline, time is not on my side sadly.

So if anyone has similar problems with this issue, I recommended using stop chemcial and applying to the area but make sure it is very diluted and washed throughly after.

My guess would be the humidity has played a part in this issue, or could be just a coincidence but in my experience, I don't often believe in coincidences.

Thank you all for the advice and I hope this has been insightful to everyone!

 

[pdeeh]

acetic acid stop bath or citric acid stop bath?