I've got the blues - Cyanotype pain

[jda]

It could be? If I'm looking at the correct paper it appears to be a lot more expensive, more difficult to source, and doesn't come in smaller sizes. For those reasons I haven't tried it. I'm also hesitant to try different papers for cyanotype right now give all my difficultly with getting the sensitizer to absorb evenly.

Eventually I'll try some other cotton papers to see if I can find one that works as well. I do agree cotton is a much nicer material than cellulose, especially when holding it or

Superior in what way?

Canson XL watercolor is an inexpensive paper that works well with traditional cyanotype, an inexpensive alt process. It is a great place to start.

There are many papers that work with cyanotype especially if you are willing to treat the paper with acid to remove the carbonate buffer present in many papers. Maybe it is a bit counter intuitive, but many inexpensive papers work well for cyanotype right out of the package probably because they do not have any (or only small amounts) of carbonate buffer in them. Carbonate is added to 'fancy' papers so that they meet one of the standards for archival-ness which less expensive papers may ignore.

A good resource for alt process papers is "The Massive Paper Chart" (see: https://www.alternativephotography.com/massive-paper-chart/). If you do a lot of alt process work the paid version is well worth the money but there is also a free version with just the basics (scroll down on the cited page).

Lastly, with regard to carbonate buffers and pre-treatment of papers with acid, I find that if I 'develop' my cyanotypes with a first wash of 15% vinegar instead of plain water, I can use papers that would otherwise require acid pre-treatment straight from the package.

Thanks for your reply,
I have a history of using 100% rag papers with pt/pd, so I'm cautious of cellulose paper. That's why I questioned the Canson Edition paper against the Canson XL watercolor which is cellulose. I'm ordering some Canson XL to try it.
I have the "Massive Paper Chart". Maybe I missed some information there.. It's hard to know how much calcium carbonate is in each paper with regards with how to treat it.
Also, doesn't that 15% vinegar wash bleach your fine highlight detail?

 

[cirwin2010]

Thanks for your reply,
I have a history of using 100% rag papers with pt/pd, so I'm cautious of cellulose paper. That's why I questioned the Canson Edition paper against the Canson XL watercolor which is cellulose. I'm ordering some Canson XL to try it.
I have the "Massive Paper Chart". Maybe I missed some information there.. It's hard to know how much calcium carbonate is in each paper with regards with how to treat it.
Also, doesn't that 15% vinegar wash bleach your fine highlight detail?

I can't speak to fgorgas vinegar wash, but I acidify the paper in 10% sulfamic acid until it stops fizzing (about 25-30 min) then give it a thorough wash.

The surface layer stops bubbling really quick in the sulfamic acid, but it takes much longer to neutralize the center of the paper fibers. Small jets of bubbles will appear at the paper edges after a while.

 

[Raghu Kuvempunagar]

with regard to carbonate buffers and pre-treatment of papers with acid, I find that if I 'develop' my cyanotypes with a first wash of 15% vinegar instead of plain water, I can use papers that would otherwise require acid pre-treatment straight from the package.

I believe this is in the context of Classic Cyanotype and the same vinegar developer wouldn't work for New Cyanotype without pre-treatment of the buffered paper.

Superior in what way?

From an archival point of view perhaps. Apparently, acid-treatment of non-rag papers introduces pulp acids or so I gathered in a Altphotolist thread.

 

[Alan Townsend]

Thanks for your reply,
I have a history of using 100% rag papers with pt/pd, so I'm cautious of cellulose paper.

This is one of my pet peeves on definitions. Provided your paper "rags" are all cotton, they are also nearly pure cellulose. Here's the Google AI:




AI Overview

Yes, cotton is almost pure cellulose (90–95%), making it the purest natural form of this polymer. It is a renewable, biodegradable carbohydrate comprising long, linear chains of glucose units, which provide strength, durability, and high absorbency to the fiber.

That's why I questioned the Canson Edition paper against the Canson XL watercolor which is cellulose.

Both cellulose, just from difference plant sources with different impurities.

I'm ordering some Canson XL to try it.
I have the "Massive Paper Chart". Maybe I missed some information there.. It's hard to know how much calcium carbonate is in each paper with regards with how to treat it.

Calcium carbonate, which is normally called "chalk" is not soluble in water and is dispersed in paper as little particles of nearly inert material. It reduces water absorbtion and physically strengthens the paper. Chalk will react with strong mineral acids, but is nearly inert to the milder organic acids used in alt processes for the most part. In art papers, it acts as a buffer to absorb acids. Since not water soluble to any degree, it doesn't affect the Ph of the paper unless a strong acid is present. Hence the acid free designation.

Also, doesn't that 15% vinegar wash bleach your fine highlight detail?

No, cyanotypes are bleached by basic solutions, not acidic solutions. The vinegar reduces the contrast of the cyanotype slightly while oxidizing the Prussian blue similar to hydrogen peroxide, so it strengthens the tones.

 

[jda]

That's a very compete

I can't speak to fgorgas vinegar wash, but I acidify the paper in 10% sulfamic acid until it stops fizzing (about 25-30 min) then give it a thorough wash.

The surface layer stops bubbling really quick in the sulfamic acid, but it takes much longer to neutralize the center of the paper fibers. Small jets of bubbles will appear at the paper edges after a while.

Thanks for the info.

 

[jda]

This is one of my pet peeves on definitions. Provided your paper "rags" are all cotton, they are also nearly pure cellulose. Here's the Google AI:




AI Overview



View attachment 419965
Yes, cotton is almost pure cellulose (90–95%), making it the purest natural form of this polymer. It is a renewable, biodegradable carbohydrate comprising long, linear chains of glucose units, which provide strength, durability, and high absorbency to the fiber.


Both cellulose, just from difference plant sources with different impurities.


Calcium carbonate, which is normally called "chalk" is not soluble in water and is dispersed in paper as little particles of nearly inert material. It reduces water absorbtion and physically strengthens the paper. Chalk will react with strong mineral acids, but is nearly inert to the milder organic acids used in alt processes for the most part. In art papers, it acts as a buffer to absorb acids. Since not water soluble to any degree, it doesn't affect the Ph of the paper unless a strong acid is present. Hence the acid free designation.

No, cyanotypes are bleached by basic solutions, not acidic solutions. The vinegar reduces the contrast of the cyanotype slightly while oxidizing the Prussian blue similar to hydrogen peroxide, so it strengthens the tones.

Thank you for the detailed response Alan.

I had not previously considered that they are both cellulose, but your explanation makes sense.

I am always open to new information, even when it challenges my current perception.

 

[koraks]

Since not water soluble to any degree, it doesn't affect the Ph of the paper unless a strong acid is present.

This is not strictly true; calcium carbonate has very low solubility in water - and that's pertinent in this case as it does in fact result in a little bleaching of a cyanotype printed on calcium-carbonate buffered paper. This can be observed by making the same print on the buffered paper and paper where the buffer was removed; the print on the buffered paper will have a slightly different hue (tending a bit towards magenta) and moreover, the most delicate highlights will be bleached back a little.

 

[Raghu Kuvempunagar]

is nearly inert to the milder organic acids used in alt processes for the most part.

If this were true then buffer neutralisation with Citric Acid wouldn't have worked. But it does work.

 

[Alan Townsend]

If this were true then buffer neutralisation with Citric Acid wouldn't have worked. But it does work.

I did use the term "nearly". I do not wish to look up the references on the Cyanomicon on this, but Ware elaborates on this subject quite a bit. Ware makes the statement many times about mineral acids required to dissolve chalk.

My crude understanding, which may be wrong, is that most weaker organic acids like citric, tartaric, acetic and others form complexes with chalk that remain in the paper. So they do have an effect, but more like a surface effect on the little grains of chalk that coat them and then change the behavior. However, the chalk is not removed, which is partly good. Removing all the chalk greatly reduces the strength of the paper.

A few years ago, I experimented with removing all the chalk in some water color papers using fairly strong (10%) muriatic (hydrochloric) acid. After an hour soak, the paper is so weak it almost falls apart when removed from the tray. After drying, it's so porous it can't be used without sizing several times. My point is that removing too much chalk can be as bad or worse than not removing enough.

I believe all we need is to remove or neutralize a certain amount of chalk that is near the surface on the side we are coating. I remember the long thread here on Photrio on using sulfamic acid soaks of various strengths for various times. Much discission on how strong and how long. Five percent and five minutes sounds good to me, but now many have increased this greatly for unknown reasons. If you recall, I use a lot of citric acid in my sensitizer, and this remains in the paper until developed,, but also only effects one side of the paper. Yes, this also helps with the chalk problem. So does a little citric acid in the wash water.

I plan on experimenting with the ferroblend process soon, and plan on using a few ml of a 5% solution of muriatic acid on one side of that paper coated just like the sensitizer, left in place for about five minutes, and then washed out. This should limit the damage to a thin layer on one side of the paper yet be effective at doing the good things we need. I think there is too much fear about the chalk removing, or acidifying the paper subject. I approach this from the direction of removing as little as I can while still getting the results I want. This conserves time and materials.

 

[koraks]

most weaker organic acids like citric, tartaric, acetic and others form complexes with chalk that remain in the paper.

I'd expect that citric acid with calcium carbonate will just become calcium citrate and carbon dioxide. Calcium citrate is moderately soluble in water and I'd expect sufficiently so to mostly wash away. Even if it doesn't, the carbonate is still gone at this point and I don't expect that the lingering citrate will do much harm.
From a more practical viewpoint I can only conform what @Raghu Kuvempunagar also said, i.e. that citric acid does appear to work to remove or at least very dramatically reduce the alkaline buffer from a paper. I guess ultimately that's what counts.
Whether or not this only happens on the surface, I don't know, but I do understand the logic that we may only have to avoid the carbonate from getting close to the image layer esp. during the time the paper is wet. However, given the marginal solubility of calcium carbonate and the sensitivity of Prussian blue to any amount of carbonate, I would expect that also remaining carbonate deeper in the fiber mat would present problems with bleaching if they remained in the paper.
And I honestly doubt citric acid couldn't get there while at the same time removing it at the superficial layers of the paper.

 

[nmp]

Organic acids will neutralize CaCO3 - take some chalk powder and drop it into citric, acetic or oxlaic acid. While calcium citrate (less) and calcium acetate (quite a bit) are water soluble as @koraks pointed out, calcium oxalate (think kidney stones) is not so it stays in the paper. Calcium sulfamate is highly soluble so it will come out easily when washed after treatment.

Secondly, the acid treatment also takes out some of the sizing agent such as gelatin (it's ph dependent) as well as perhaps other additives - that also makes the paper more porous as well as more hydrophilic. That in itself can also affect the outcome of the process.

In other words, it is complicated.

:Niranjan.

 

[Alan Townsend]

I'd expect that citric acid with calcium carbonate will just become calcium citrate and carbon dioxide. Calcium citrate is moderately soluble in water and I'd expect sufficiently so to mostly wash away. Even if it doesn't, the carbonate is still gone at this point and I don't expect that the lingering citrate will do much harm.

Not a chemist, but my understanding is that many complexes form using buffered papers. May not be as simple as you suggest. My memory is that soluble chemicals do not form since they remain ions in solution. The least soluble chemicals would remain, which is calcium carbonate in the many complex forms that it has. The amount in solution is a little under 0.002 g per liter.

From the cyanomicon II page 215

If buffered papers are unavoidable, such as Fabriano Artistico, or
Whatman Watercolour, the chalk should be destroyed by pre-treated in a
bath of dilute (5% v/v) hydrochloric acid, or 5% - 10% w/v sulphamic acid,
for about 10 minutes, then washed.

page 276

Most contemporary practitioners have been driven
to the last resort of soaking their chalk-buffered papers in dilute acid in
order to destroy the calcium carbonate before coating them with iron(III)
sensitizer. Unfortunately many practitioners think that oxalic acid is also
suitable for this purpose, but calcium oxalate is just as insoluble as
calcium carbonate. Hydrochloric acid can be used, but recently it has
been found very convenient and effective to employ 10% sulphamic acid
for this purpose.677 Nonetheless, it is a tedious and unnecessary
procedure that tends to degrade the paper surface and strength.

Citric acid is mentioned as additive for preventing fogging on p. 216

7.4.6 Citric acid prevents fogging
Chemical fogging (“greening”) of the coating due to paper impurities may
often be prevented by adding citric acid to the sensitizer, before coating,
to a final concentration of
ca. 2%. Add one drop (0.05 cc) of a 40% w/v
solution of citric acid per cc of sensitizer. Do not add citric acid to the
stock of sensitizer, because it will shorten the shelf-life.

The organic acids are not mentioned for use to remove the chalk, although one would think eventually that may work. The low solubility like me mentioned with oxalic is likely part of the problem.

From a more practical viewpoint I can only conform what @Raghu Kuvempunagar also said, i.e. that citric acid does appear to work to remove or at least very dramatically reduce the alkaline buffer from a paper. I guess ultimately that's what counts.

The test of this is if his prints fade in the next fifty years or so. Ware is adamant about removing all the buffer, even though testing has shown only the buffer contacting the image is relevant.

Whether or not this only happens on the surface, I don't know, but I do understand the logic that we may only have to avoid the carbonate from getting close to the image layer esp. during the time the paper is wet. However, given the marginal solubility of calcium carbonate and the sensitivity of Prussian blue to any amount of carbonate, I would expect that also remaining carbonate deeper in the fiber mat would present problems with bleaching if they remained in the paper.

There would be almost zero carbonate ions in the paper, since as the paper dries they will form stable compounds. In dry paper, the calcium carbonate is locked in position.

And I honestly doubt citric acid couldn't get there while at the same time removing it at the superficial layers of the paper.

Not sure what you mean here. I really hate looking up references in the Cyanomicon. Bottom line si Ware says use muriatic acid of sulfamic acid to remove the chalk. The weaker acids would take much more time. How deeply in the paper do we need to remove or disable chalk is the experiment I will do in the near future.

 

[Raghu Kuvempunagar]

From a more practical viewpoint I can only conform what @Raghu Kuvempunagar also said, i.e. that citric acid does appear to work to remove or at least very dramatically reduce the alkaline buffer from a paper. I guess ultimately that's what counts.
Whether or not this only happens on the surface, I don't know, but I do understand the logic that we may only have to avoid the carbonate from getting close to the image layer esp. during the time the paper is wet. However, given the marginal solubility of calcium carbonate and the sensitivity of Prussian blue to any amount of carbonate, I would expect that also remaining carbonate deeper in the fiber mat would present problems with bleaching if they remained in the paper.
And I honestly doubt citric acid couldn't get there while at the same time removing it at the superficial layers of the paper.

If Citric Acid doesn't neutralise all or most of the buffer, then one would expect to see some bubbling of Carbon Dioxide, due to the residual buffer, in the development stage of New Cyanotype where Sulphamic Acid is used. I haven't seen any with Lanaquarelle.

 

[jda]

Looking for suggestions: What ratio citric acid to 1000ml water do you recommend for de-buffering. I know it varies by paper. 2 g:1000ml is what have used and it is too weak.

 

[koraks]

I know it varies by paper

Not really. You just want an excess.
If you assume that the paper will only contain a certain % of weight of buffer material and you know the weight of the paper, then you can work out how much you need.

I would say that a few grams of citric acid per sheet will do the job and you only need enough water to fully submerge the paper - assuming you're going to do one or a couple of sheets at a time.

 

[Alan Townsend]

If Citric Acid doesn't neutralise all or most of the buffer, then one would expect to see some bubbling of Carbon Dioxide, due to the residual buffer, in the development stage of New Cyanotype where Sulphamic Acid is used. I haven't seen any with Lanaquarelle.

Cyanomicon II p. 260

Fading of Prussian blue requires the simultaneous presence of several
contributing factors: light; a reducing agent (electron donor) in intimate
contact with the solid; and cations to migrate into the lattice and balance
the increased negative charge brought about by reduction. Molecules that
are small enough to be occluded within the voids of the Prussian blue
lattice should be particularly effective in promoting the photoreduction.
To test this possibility, pure Prussian blue coatings on paper were
prepared by successive coats of potassium ferricyanide and ferrous
sulphate, then part-coated with solutions of oxidisable anions such as
citrate and oxalate, and allowed to dry. The density of the impregnated
Prussian blue paper was compared with the control region after a period
of dark storage to ensure that there was no reduction in the dark, then
the whole sheet was given a standard fading exposure. The reductant-
coated area was found to fade in the light much more rapidly than the
control area, showing that these oxidisable organic anions do indeed
promote photoreduction of the pigment. It may be significant that the
anions effective in promoting fading in Prussian blue are also those that
normally render iron(III) photoactive in its salts, and are consequently
present in the cyanotype sensitizer.
To improve the light fastness of cyanotypes, therefore, the presence of
excesses of these free anions, such as citrate or oxalate, should be
avoided. Since an acid development bath is desirable in the processing of
new cyanotypes (
Ware formula employing ferrioxalate sensitizer), it is
better to use a very dilute mineral acid such as hydrochloric or nitric,
rather than citric or oxalic acids, which have been previously
recommended.

So Ware suggests hydrochloric acid or sulfamic acid for buffer removal without loss of lightfastness. Also, from other reading I've done, the organic acids take much longer to remove the buffer, and complexes with oxides and hydroxides complicate the chemistry.