View Full Version : Cyanotype - 10 times faster

03-17-2011, 02:42 PM
why does nobody use the second cyanotype process, the one hershel used?

Solution A: 400g ferric ammonium citrate green in 1l of destilled water (store in dark bottle)
Solution B: 10g potassium ferricyanide in 1l of destilled water

Float paper in solution A (or use a brush)
dry (dimmed light!)
expose about 10 times less than with the original cyanotype formula. You will see a faintly printed image on your paper. The darkest shadows should have the colour of the not-exposed paper.
float the paper in solution b (a brush can reduce the resolution of the print)
wash until all the yellow is gone.
dry (and wait 1h for the full contast.)

Advantages: it gives me sharper prints 10 times faster
Disadvatages: you need a lot more chemicals

try it!

p.s. this is where i found it: (in german)

03-17-2011, 03:51 PM
Do you have some samples?

03-17-2011, 04:07 PM
Why not immerse the paper in solution b? I don't see the need for the float, if the unused solution washes out. I, too, would like to see some images, especially if you have the same image done with this process along side traditional cyanotype or Mike Ware's new cyanotype.

03-17-2011, 07:22 PM
@earlj - sorry, i meant immersing (bad english)

proof of concept from a 30x40cm paper negative (foma 311n, paterson acu, arches aquarelle 21x29cm cold pressed precoated with gelatine/formalin/tween)


the exposure time was 1h10min. Usually I expose for 12h using the traditional A&B mix.

full 300dpi scan (7 megs) http://quanttrader.at/img043.jpg

anyhow, seeing the negative you can guess what is lost on the print. If anybody can tell me how to avoid this - please help ;-)
http://quanttrader.at/img044s.jpg (scanner too small for full image)

i brushed this image with solution A 2 times and immersed it in B for development.


03-17-2011, 08:07 PM
You have a pretty nice range of tones in this print. Traditional cyanotype does not display a long contrast range, and you seem to have a negative with a pretty broad range. I don't know what your density range is, but this print looks pretty darn good to me.

I am going to give this method a try. The extra chemicals is no big deal, as cyanotype chemistry is cheap, and you can re-use the 'developer', can't you?

03-18-2011, 08:08 AM
to be true I have got no practical knowledge about reusing the chemicals. I would assume that you can reuse the sensitizer. The developer is polluted with a lot of blue and unexposed sensitizer.
But if you keep it in a dark place...

I used the developer for several prints and kept it dark in between. Everything was fine.

But it is my third day with this formula - and I could not find anything on the net about it...

Let me know how it worked out with your negs!


p.s. There is an alternative formula for this process give in Cassell`s cyclopedia of photography (1911) page 68. But it uses uranium nitrate and a much higher concentration of solution B.

if you search for "the alternative method is to use single solutions" at google books you`ll find the except. (sorry I don`t know how to link directly)

p.p.s I had some bad experience with hot pressed arches aquarelle paper. It seems that the tonal range of the print depends on how much sensitizer is applied to the paper.

03-18-2011, 01:17 PM
I too am hard pressed to see the shortcomings in the print. The only shadow dropout is the door way at the bottom, but the mid-tone separation is excellent. I haven't seen many examples like you have here.

Doug K
03-18-2011, 02:40 PM
Interesting process and nice print. I'm heading out of town for 2 weeks, so I won't be able to try this this weekend, but I will when I come back. I expose in the sun, and my times usually run around 6 minutes or so. The faster exposure might be just what I need with my UV LED lightbox experiment. The speed of the formula isn't so much an interest for me with sun exposure, but I do like the tonal range.

03-18-2011, 06:40 PM
Hi Phil.

Is this method similar to the Cyanotype Rex process? I did try splitting parts A and B a while ago but only brushed on part B to develop and had issues with the brush marking the print. What is the quantity of part B you use for your development bath? Do you use a full litre?

Best regards,


03-19-2011, 03:54 AM
Hi Evan,

I have got no idea about the REX process. I never did it...

You do not need 1l of the solution to start. I tried immersing and brushing, and if you use a hake brush, the outcome is about the same.
For my tests i setteld with brushing on A and immersing in B.

If you overexpose the print a lot of collodial blue is build on the print when you immerse it into the developer. If you clean off this collodial blue with a soft shower, an unsharp picture reamins which has not got a nice blue. If you use a brush you get heavy brush strokes.


p.s. i am off for 3 days

03-19-2011, 07:20 PM

I have just re-read your first post and noticed the quantities are quite different from 'traditional' cyanotype:

Solution A: 400g ferric ammonium citrate green in 1l of destilled water (store in dark bottle)
Solution B: 10g potassium ferricyanide in 1l of destilled water

For my 'traditional' version, I use A: 250g of FAC in 1L and B:100g of PF in 1L. A bath of potassium ferricyanide at 10g per litre is a 1% solution and therefore quite cheap as my normal 'part B' is 10 times the strength. Your part A is almost twice the strength of my part A however. Is the 1% solution for part B correct? Hopefully I will get a chance to try your formula over the next few days; the thought of a longer tonal range is very appealing!

Best regards,


03-19-2011, 07:52 PM
1% works! But I did not test if you could reduce the concentration of solution A. 40% is a lot!

03-22-2011, 08:09 AM
Collodial Blue - Solarization

This is a test strip which shows the effects of an overexposure:


Look at the right end of the strip. This is where the negative ended. First you see the dark blue stains. They do not adhere to the paper very good, thus using a brush, you would distribute this overexposed blue over your picture and get the brush stains.

Second you see that there is only a light blue on the right end of the strip. The picture itself has got a darker blue. Solarization.

I never observed this with the traditional process. There the solarized areas on the picture give the darkest blue possible. (after washing and drying)

In general, with this alternative cyanotype process the exosure time seams to have a much higher impact than with the traditional mix.

did you guys find out something new?


03-24-2011, 06:20 PM

I managed to do a quick experiment a few days ago and now all the images have had a chance to oxidise fully. To fix some of the variables, I cut an 8"x10" sheet into 4 pieces and tried different sensitiser and exposure combinations to establish the speed of the sensitiser for generating shadow density, and then also to give an indication of the usable tonal range. I used a digi-neg 101 square test target where each square is a 1% black level change in photoshop. There is also a fragment of a picture of a dog in each image to see the impact of the change of variables.

In the image,
1. The top left hand test target is from a coating of 40% FAC solution, developed in 1%PF, exposed for 5 minutes under my UV lamps.
2. The top right test is a coating of 25%FAC in a 3% gelatine solution, exposed 10min and developed in 1%PF.
3. The bottom left test is my normal 25%FAC+10%PF coating exposed for 10 minutes and developed in 1L water with 1.5ml of 10% Hydrochloric acid.
4. The bottom right test is the same coating as in (1) above, but 10 minutes exposure

I had most of the dark blue in images 1 and 4 wash off in the developer in a similar manner to the border of your last image Phil, however the blue reached full density almost instantly on development, rather than having to wait for it to oxidise. The 'traditional' cyanotype in (3) took a day to oxidise but the final density of the blue appears to be darker than in (1) but not as dark as in (4), suggesting the alternative coating method is roughly 1/2 stop faster for shadow density. The main difference though is the range of tones in the alternative method is massive when compared to the traditional cyanotype; a very real bonus! In my 101 step % scale, the traditional process only has useful tones in the 0-15% range, whereas the alternative method has useful tones in the 0-35% range.

Test (2) was an experiment. For previous work with cyanotype-on-glass I mixed a 3% gelatine solution and added 25% FAC to it. Out of interest I tried this emulsion with the alternative development method, hoping the gelatine would act as a binder to keep the Prussian Blue in situe; I had no noticable wash off of the blue whatsoever! For the tests I used the 1%PF solution as one-shot but with the gelatine in the sensitiser mix, I am sure I could have used the developer for a fair few images as it looked the same colour as the mix left in the bottle! The 25% compared to 40% of FAC does not seem to have altered the shadow density or tonal range much, if anything the 25% mix appears to have darker shadow detail, but it may also be an effect of the gelatine holding more pigment in place.

I plan to do a few more tests on a wider range of papers to see how repeatable the results are; the method is well worth perfecting to capitalise on the fantastic tonal range.

Best regards,

Evan Attached files http://f295.f295.org/uploads/cyano_comparison_small_8456.jpg (http://f295.f295.org/uploads/cyano_comparison_small_8456.jpg)

03-25-2011, 04:39 PM
Hi Evan,

Thanks for the great tests! 8) I especially like the top right.
I`m out of chemicals and have to be patient for a week or so :-(


p.s. I never tried mixing the gelatine with the FAC, but it seems to give great results. You did not add any hardening agents like formalin to the gelatine?

03-25-2011, 04:47 PM

Looking back through my notes, I did add 5 drops of formalin to 50ml of the gelatine solution; the formalin was added just to preserve it rather than harden it. The gelatine/FAC mixture sits in a brown bottle in my garage and I just warm it for a few seconds (hot water or microwave) to melt it. I actually mixed it just over a year ago and it is still in great condition so the formalin must just be about the right amount!

I just did another test, but as I was low on the 1%PF solution, I diluted it to about 0.3%. OOPs! the blue takes much longer to develop, but the extra water seems to wash out the FAC before it has had a chance to turn blue! The developer solution had a lot of blue in it and the print is far paler than before. The 1% solution seems to be a good compromise between near-instantaneous development so the FAC does not wash out and cost.

Best regards,


03-25-2011, 05:00 PM
Evan - the only addition that I would make is to try Mike Ware's new cyanotype recipe in the testing. Perhaps I can get up the steam to take a whack at it myself.

03-25-2011, 05:11 PM

Yes it would be interesting to see. I do not have any of Mike Ware's cyanotype at the moment though unfortunately. Interestingly, the tonal range/density I need from a negative for this alternative approach is the same as I am using for carbon transfer, although for digi negs, the curves are quite different.

Best regards,


03-30-2011, 07:11 AM

there is one point in your post that confuses me: the speed.
You mention that the split process is about a 1/2 stop faster than the traditional. (using your uv)

I did a couple of prints yesterday - and every print was done in less than 1/10 of the original time. Using my 4*60w uv lamp 10cm above print. This is 3-4 stops faster than the original process. With paper negatives i need about 1 hour under my uv-lamp (used to be 12h), with the sunshine 1/2h. Usually I leave the prints outside for 12h, with about 4h fully in the sun, the rest is shade. (Berlin)

I will post some prints of the same negatives using split and traditional process next week. The first results show no "world moving" differences - so for me the speed is the main argument for the fuss.


p.s. double coating seems to enhance the the tendency for the dark blue to detach, pre-lightning the paper just below zone 1 saves another 1/2 stop in total exposure time.

p.p.s first tests using your "gelatine-mix" turn out great! Higher densities, faster (due to no wash off)

Thank you for this!!

03-30-2011, 06:41 PM

My half-stop estimate relates to the Dmax (i.e. the darkest blue) and is an easy 'reference point' to monitor. Evaluating where the paper goes 'just white' in the highlights is really tricky to do accurately and I did not try to calibrate the highlight end, but it would take far more than 1/2 a stop extra exposure to make the highlights on the traditional cyanotype go just-white at the same negative density as the split method. For example, if you take the lowest dark blue set of squares in my test images as 'row 1' then in the lower right image, even at the end of row 5 there is a hint of blue. In comparison, for the traditional method in the bottom left, the end of row 3 is already completely white. The rows are in percentage steps in photoshop and not true stop-steps, but there is a huge difference in the tonal range. To get the traditional method to go just white at the end of row 5 would need much more exposure; I could quite believe that it may need 3 1/3 stops more which would equate to the factor of 10 you are observing.

I have often wondered, but never tested, if cyanotype suffers from reciprocity failure too; if it did it may also account for part of the apparent speed increase you see, but is unlikely to be present in my results with my comparatively short exposure times. One day I may do the experiments to test for reciprocity failure, but I really need a brighter UV source still to make sure I can get some very short printing times too. I think my garage is long enough to move the paper far enough away from the UV source to get exposure times of a few hours.

Best regards,


PS, I am glad the gelatine is working for you too; I have not tried double coating yet either so may have an experiment over the weekend.

03-30-2011, 10:32 PM
Interesting thread!
A question was asked about the cyanotype rex process. This is Terry King's "re-invention", in which the paper is sensitized with ferric oxalate and developed with potassium ferricyanide. You have to buy the PDF from him to get the details :p but that's the basic idea.

03-31-2011, 01:04 PM
Thanks Mary,

Looks like Rex is the same method, but just slightly different chemistry. I am guessing it is Ammonium Ferric III Oxalate that is used; luckily I have some so it may be a busy weekend!

Best regards,


Edit: With further thinking, Ferric Oxalate plus a bit of acid may be better ...