Cyanotype Beginner Question: How to Reduce Graininess?

I recently started cyanotype, and I have a question I’d like advice on. Please take a look at the attached ChartThrob image (10cm x 10cm).
The graininess is quite noticeable. Is this normal?

The paper I’m using is Arches Watercolor Paper, Hot Pressed, (300gsm), Natural White.

I’m using Jacquard sensitizing solution, double coating it. After applying the solution, I dry it with a low-temperature hair dryer for about 15 minutes each time. The room humidity is around 40–50%.

I’ve looked into various solutions to address this issue, but I haven’t been able to find anything that works.

Is there any way to reduce this graininess?

Thank you!

Why are you double coating? I have never found this necessary.

How long are you waiting for the sensitizer to soak in before applying heat? I try to avoid 'forcing' the drying stage with heat. If you are going this route, I would probably wait about 5 min after coating (the paper should not show any sheen) before applying heat.

I much prefer to let paper dry at ambient temperature for an hour minimum before exposing. I tend to coat a batch of paper (six to ten sheets) at the beginning of a dim room session and expose the first sheet starting an hour after I sensitize the last sheet.

Lastly, and probably most importantly, try adding Tween 20 to the sensitiser. I keep a 10% (w/v) stock of Tween 20 and add 1-2 drops of this stock per half mL of senstizer. The amount is very dependent on the paper. Tween 20 is also know as Polysorbate 20 and is readily available on Amazon.

If all else fails, try a different paper even though Arches Aquarelle is supposed to be usable for cyanotype.

The graininess is not normal.

How are you coating the paper? The biggest issue I see with folks getting started is getting the coating process working right.

Frank pretty much summed up what I was going to say.

I'd recommend you try acidifying the paper beforehand. I almost always do that with any paper, although with some you don't need to, but it almost never hurts. Also keep the process acidic until you wash. I even put acid in the mix before I coat. Citric acid is what I use for a first bath after exposure. One teaspoon in a liter of water is about right. For acidifying the paper I use Sulfamic Acid usually, but sometimes I use Citric if I'm lazy. You acidify the paper and then wash and dry it before you coat it. If you put the paper in acid and it bubbles, then you need to acidify it. Acidifying everything also has the benefit of making the paper last a long time. I've printed weeks later.

I've never used Arches that I can recall so I can't comment on that. I'd recommend that you use one of the papers that are more or less made for alt processes. Bergger COT or Revere Platinum both work easily.

Hope that helps.

D_Quinn said:

Is there any way to reduce this graininess?

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Yup, avoid double coating and extensively brushing around the sensitizer. It looks like you're damaging the paper surface, which can be rather sensitive when the paper is wet, and dislodging fibers.
Careful technique is one part of the answer to your question, another part is trying a couple of different papers until you find something that suits your taste. But the former is the major aspect of your present problem.

A third aspect is the nature of the (inkjet) negative itself. Inkjet negatives can give a rather coarse/grainy rendering. It often helps to try a different combination of ink channels to get a smooth tonal range. In doing so, try to find a configuration that creates not excessively more density in the negative than your process requires. The result of this would be a very dramatic adjustment curve, and that tends to emphasize coarseness and introduce issues with posterization. Classic cyanotype has a very steep curve and thus requires very little density to block the highlights; something like 1.2logD (by comparison, salted paper likes >2.1logD, which is only 0.1% of the transmittance!) You may get the best results using a different combination of ink channels on your printer than what you've been using so far for other processes.

D_Quinn said:

I’m using Jacquard sensitizing solution

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Did you buy this as a kit that comes in the form of two powders that you need to mix with water and then combine? What is the color of the sensitizing liquid at the moment it's being brushed onto the paper? How does your sensitized paper look once it's dry, immediately before exposure?

fgorga said:

I try to avoid 'forcing' the drying stage with heat. If you are going this route, I would probably wait about 5 min after coating (the paper should not show any sheen) before applying heat.

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We all have our ways, but I consistently blast my alt. process prints dry virtually immediately after coating. It works great and does not present any problems with fogging etc. The worst that can happen is if the coating is a little heavy, a droplet is blown to a corner of the sheet. To prevent this, dab up any 'ridges' or droplets of sensitizer from the edges of the sensitized area with a piece of tissue paper. Then blast away with the hairdryer on maximum heat to dry the paper within a minute.

You have lots of good responses - I'll add a couple of things.

1. How big is your test print - seems to me, judging by the fiber structure I see of the paper on the side, the image you have presented is enlarged. How does it look at 1:1 at eye level? Perhaps it it not so bad as you think. Print an image and you will find it is not as distracting as you might envision. As a matter of fact it might actually add to the charm of the print, depending on the subject.

2. Secondly, given that the "grain" mimics the paper fiber structure (to my eye at least when you compare the bare paper in the periphery) - I would simply go to a paper that is smoother (as recommended above - such as COT320 or HPR, etc) before doing anything significant with the process/chemistry (except double coating - which in my experience is not worth the trouble) and see where that leads you. Very good chance what you are seeing is a manifestation of the rough surface of the paper even though it is hot-pressed. If the other side is smoother, try using that side and see if that makes a difference.

Good luck.

:Niranjan.

Thank you everyone for your many helpful pieces of advice!

Regarding the double coating, I read somewhere that it enhances the tonal range by making the Dmax darker, so I’ve been using a foam brush to apply it. However, as koraks mentioned, I may have been damaging the surface by going over it multiple times. I’ll give single coating a try and see how it improves.


I also used a hairdryer (on a low setting) immediately after applying the sensitizing solution, so perhaps the solution didn’t penetrate deeply into the fibers. I plan to compare the results between using a hairdryer and natural drying to see what differences arise.


As for Tween 20, I found Polysorbate 20 and ordered it right away!


The actual size of the chart is 9.5 x 9.5 cm (3.7 x 3.7 in). So, when viewed on a computer screen, the chart should appear larger than its actual size. That said, even looking at the physical chart, the mid-tones do appear grainy, which surprised me a little, as I’ve never seen a cyanotype in person before.

As for the paper, I have Canson XL and Hahnemühle Platinum Rag, so I plan to try those this weekend! I'll find a smoother side of those papers. If the same issue persists, my next step will be to acidify the paper.


Many thanks

D_Quinn said:

Thank you everyone for your many helpful pieces of advice!

Regarding the double coating, I read somewhere that it enhances the tonal range by making the Dmax darker, so I’ve been using a foam brush to apply it. However, as koraks mentioned, I may have been damaging the surface by going over it multiple times. I’ll give single coating a try and see how it improves.


I also used a hairdryer (on a low setting) immediately after applying the sensitizing solution, so perhaps the solution didn’t penetrate deeply into the fibers. I plan to compare the results between using a hairdryer and natural drying to see what differences arise.


As for Tween 20, I found Polysorbate 20 and ordered it right away!


The actual size of the chart is 9.5 x 9.5 cm (3.7 x 3.7 in). So, when viewed on a computer screen, the chart should appear larger than its actual size. That said, even looking at the physical chart, the mid-tones do appear grainy, which surprised me a little, as I’ve never seen a cyanotype in person before.

As for the paper, I have Canson XL and Hahnemühle Platinum Rag, so I plan to try those this weekend! I'll find a smoother side of those papers. If the same issue persists, my next step will be to acidify the paper.


Many thanks

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For what it’s worth I got results like this when coating with a foam brush. I ended up giving up on foam brushes and buying a nice hake brush and I would never go back. My suspicion was that the foam ended up roughing up the paper fibers, even when I was being gentle.

These are what I use: Creative Mark Mandalay Artist... https://www.amazon.com/dp/B0049UZJUI

aconbere said:

For what it’s worth I got results like this when coating with a foam brush. I ended up giving up on foam brushes and buying a nice hake brush and I would never go back. My suspicion was that the foam ended up roughing up the paper fibers, even when I was being gentle.

These are what I use: Creative Mark Mandalay Artist... https://www.amazon.com/dp/B0049UZJUI

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Indeed. That can be a culprit! I’ll get a soft hake brush tomorrow. Thank you!

Yes, a soft hair brush works best IMO for cyanotype. Doesn't have to be very expensive, although a good-quality brush is generally a worthwhile investment. The brush I use the most for this kind of work cost me around €15. Just to illustrate that affordable stuff often works just fine.

I really wouldn't worry about the hairdryer; on a suitable paper, the emulsion adheres to the fibers in mostly the upper layer of the paper virtually instantly.
I personally never use a wetting agent or surfactant (photoflo etc.) because in my experience it does more harm than good. By breaking the surface tension of the sensitizer, it tends to soak in far too deep into the paper, causing mottling and problems with clearing later on.

nmp said:

... As a matter of fact it might actually add to the charm of the print, depending on the subject....

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I don't have much to add, but was entertained by this comment because it was the first thing I thought of. I sometimes print my negatives on plain cheap printer paper because I like the textures I can get that way..... My first reaction to seeing this post was "maybe I should try arches hot press to get texture like that"... and what nobody else mentioned was that you seem to have perfect whites available, which isn't always easy to do with non-acidified paper that wasn't made for alt processes ( like COT or HPR ).

Patrick Robert James said:

I'd recommend you try acidifying the paper beforehand. I almost always do that with any paper, although with some you don't need to, but it almost never hurts. Also keep the process acidic until you wash. I even put acid in the mix before I coat. Citric acid is what I use for a first bath after exposure. One teaspoon in a liter of water is about right. For acidifying the paper I use Sulfamic Acid usually, but sometimes I use Citric if I'm lazy. You acidify the paper and then wash and dry it before you coat it. If you put the paper in acid and it bubbles, then you need to acidify it. Acidifying everything also has the benefit of making the paper last a long time. I've printed weeks later.

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Yes. Removing carbonate buffers is very important for cyanotype. This is one process where the problem caused by carbonate buffers is well understood. Very simply, Prussian Blue (the pigment which forms a cyanotype) is susceptible to hydrolysis by alkali. The 'carbonate problem' usually shows up as an print that looks good when it comes out of the print frame becoming very weak upon washing in water (as the Prussian Blue is destroyed).

This can be avoided by, as @Patrick Robert James says by pre-acidifying the paper. I have also found that 'developing' a cyanotype in 10% (v/v) vinegar as the initial wash works perfectly well with carbonate-containing papers. In this case the acid neutralizes the carbonate quickly enough to avoid significant hydrolysis of the pigment.

That said, I would not bother pre-acidifying papers made specifically for alt process printing (e.g. HPR, Bergger Cot, Platine and Revere Platinum). These papers do not contain carbonate buffers by design. Thus acidifying them is not needed and might cause other issues.

koraks said:

We all have our ways, but I consistently blast my alt. process prints dry virtually immediately after coating. It works great and does not present any problems with fogging etc. The worst that can happen is if the coating is a little heavy, a droplet is blown to a corner of the sheet. To prevent this, dab up any 'ridges' or droplets of sensitizer from the edges of the sensitized area with a piece of tissue paper. Then blast away with the hairdryer on maximum heat to dry the paper within a minute.

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Absolutely!!! I always tell beginners that "this is my way of doing things but it is not the only way" and they are required to find what works for them!

koraks said:

Yes, a soft hair brush works best IMO for cyanotype. Doesn't have to be very expensive, although a good-quality brush is generally a worthwhile investment. The brush I use the most for this kind of work cost me around €15. Just to illustrate that affordable stuff often works just fine.

Click to expand...

Agreed!

I find that inexpensive 'gold' Taklon brushes such as these (https://www.amazon.com/Plaid-Enterprises-Inc-50557E-2-Piece/dp/B00J8HCPAY/) or these (https://www.amazon.com/Royal-Golden-Taklon-Brushs-Assorted/dp/B0018MD600/) work well for all alt processes. (Well at least the processes I have tried.)

Traditional Hake brushes also work well. However they are very absorbent and thus soak up a lot of sensitizer. This is not a real problem with inexpensive chemistry such as cyanotype and only becomes a real issue when using precious metals.

As an aside, save yourself some trouble by dedicating brushes to a single process. Cleaning brushes to avoid cross contamination is nigh impossible. Ask me how I know!!!

koraks said:

I really wouldn't worry about the hairdryer; on a suitable paper, the emulsion adheres to the fibers in mostly the upper layer of the paper virtually instantly.
I personally never use a wetting agent or surfactant (photoflo etc.) because in my experience it does more harm than good. By breaking the surface tension of the sensitizer, it tends to soak in far too deep into the paper, causing mottling and problems with clearing later on.

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I agree to a point. Most folks use surfactants at too high a concentration which can cause troubles as @koraks suggests.

That said, watercolor papers are the one type of paper where surfactants can often help. Watercolor papers (as compared to say printmaking papers) are heavily surface sized in order to keep water color pigments on the surface and thus easily workable when painting. Thus a little assist in getting sensitizers into watercolor papers is often useful.

However, I find that low concentrations of Tween 20 do not generally cause a problem with printmaking papers (or with alt process specific papers) and Pt/Pd or salt printing. But I'm not sure I have done enough testing to say this for sure with cyanotype.

Lastly, I'll say that I find Fabriano Unica (50% cotton) a very useful paper for cyanotype. It is inexpensive and thus 'matches' the cost of the sensitizer.

fgorga said:

That said, watercolor papers are the one type of paper where surfactants can often help.

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Yes, that's a very valid remark and I should have clarified that I mostly use printmaking papers. Watercolor papers indeed have a much more closed surface to the point where it almost appears to repel water. Btw, this is not the reason I rarely use them - it's their pronounced texture that I find a bit too oppressive for the kind of prints I like to make.

I agree with Frank, again, that Taklon brushes seem to be the most useful that I have found. They perform better than even those Richeson brushes that "everyone" swears by. Those are a waste of money I think. Mine just sit in the drawer these days. You can get Taklon brushes almost everywhere and they are pretty cheap. I am not fond of Hake brushes for coating cyanotype. They don't have any spring to them which makes coating with them a bit frustrating once they start drying out. I do like them for evening out the coating for gum prints though. They are fantastic for that.


You really just need to try different things and see what works for you. I suppose that is half the fun anyway.