Van Dyke over Cyanotype

[Bronson Dugnutt]

There was cyanotype + salt print process I experimented with a few years ago with some success.

I separated the original negative into two; one for the salt print and another for the cyanotype then proceeded as follows:

1. Expose, process, and dry the salt print as usual.
2. Sensitize the print with cyanotype solution. Note: This will bleach out the silver image due to the ferricyanide.
3. Expose and process the cyanotype as usual.
4. Brush a dilute developer solution (I used HC-110) onto the bleached silver areas to redevelop the silver.

You can see an area in the lower right hand corner where I failed to redevelop a portion of the silver.
The alkaline nature of the developer causes bleaching of the cyanotype so its a bit of a balancing act. A slightly acidic amidol developer might work for tray processing but the paper would probably stain.

 

[nmp]

There was cyanotype + salt print process I experimented with a few years ago with some success.

View attachment 252681

I separated the original negative into two; one for the salt print and another for the cyanotype then proceeded as follows:

1. Expose, process, and dry the salt print as usual.
2. Sensitize the print with cyanotype solution. Note: This will bleach out the silver image due to the ferricyanide.
3. Expose and process the cyanotype as usual.
4. Brush a dilute developer solution (I used HC-110) onto the bleached silver areas to redevelop the silver.

You can see an area in the lower right hand corner where I failed to redevelop a portion of the silver.
The alkaline nature of the developer causes bleaching of the cyanotype so its a bit of a balancing act. A slightly acidic amidol developer might work for tray processing but the paper would probably stain.

Coincidentally, last couple of days I abadnoned my regular cyanotype work - no doubt inspired by the original premise of this tread, and jumped back into something I had started long time ago but didn't follow up as usual - namely, blue toning of POP and salt prints. I was going to start a separate thread, but may be I can describe the basic concepts here.

You don't have to do the actual cyanotype over the salt or VDB - you can get chemically identical results but with much better control and much ease (tray processing) if you follow the path of classic blue toning process and then revive the silver. First part is relatively easy, the last part as you are reporting is tricky.

Here is how I am approaching it:

Step A: Bleach + blue-tone salt print in K Ferri + FAC + KBr mixture.

Si converts to Si ferrOcyanide releasing K FerrOcyanide
K FerrOcyanide combines with KFerri to form Prussian blue
Si ferrOcyanide converts to silver bromide releasing one more K FerrOcyanide which further makes Prussian blue
Print is now all blue, having Silver been converted to pale yellow bromide

Step B: Convert silver bromide to image-forming silver.

B1) Use indirect toning - take your pick. I am looking at thiourea carbonate as well as home concoction of Black salt I have used in the past to tone salt prints.

B2) Develop - Bring back silver metal by using a reducing developer such as the regular paper developer as you are using. I don't have the traditional darkroom chemicals. I am wondering if a simple (ascorbic acid + base) developer will suffice, which I have plenty of. [I am also wondering if an alkali can be simply taken out of a developer as its function (as I understand) is to accelerate and increase contrast - latter is important if you are developing a print from a latent image. What we are doing here is simply flash expose and develop to the same degree all over. Perhaps the next step can be eliminated, if that is the case.]

If an alkaline developer is used, the blue will be bleached by the basic nature of both the developer (may be amidol is an exception) and toner, essentially forming yellow ferric hydroxide.

Step C: Regeneration of Prussian blue.

Treat the paper with K ferrOcyanide.
Ferric hydroxide reacts with K ferrO to form Prussian blue.

Now, in theory, your starting 1 atom of silver results into 1 atom of silver (or silver sulfide or combination) and if the reactions are efficiently performed 1 molecule of ferric ferrocyanide or Prussian blue.


:Niranjan.

 

[glbeas]

I made another test with the Mrhar calibration square and a Stouffer scale. I took a picture of it just as I got it out of the print frame and after processing it. Looking at the Stouffer scale it seems the exposure could be reduced a half stop, but if the neg is calibrated to that exposure it shouldnt matter so much. Im also wondering if its the process or the Stonehenge paper that is keeping the Dmax down. The image looks grainy in the shadows like the prussian blue is not sticking as well to the texture of the paper.

 

[nmp]

I made another test with the Mrhar calibration square and a Stouffer scale. I took a picture of it just as I got it out of the print frame and after processing it. Looking at the Stouffer scale it seems the exposure could be reduced a half stop, but if the neg is calibrated to that exposure it shouldnt matter so much. Im also wondering if its the process or the Stonehenge paper that is keeping the Dmax down. The image looks grainy in the shadows like the prussian blue is not sticking as well to the texture of the paper. View attachment 252741 View attachment 252740

Yes, paper has its own inherent limitations on how much pushing and pulling you can do with all the tricks. So sometimes you get a break when the paper is just right.

Anyway, if I look at the Stouffer, I think there is still difference between step1 and step2. If that is the case, then you can still increase the exposure. Is the Stouffer under the negative or beside it? In order to calculate the standard exposure time (minimum time for maximum density) you will have to expose just the step wedge with a blank Pictorico for much longer time, say 30 minutes or so, so that lower steps merge at some level. From that you can back-calculate the correct exposure after compensating for the base density of the Stouffer. I am sorry if I am repeating something you already know.

:Niranjan.

 

[glbeas]

The Stouffer is beside the negative.

 

[nmp]

The Stouffer is beside the negative.

In that case, you have to subtract the base density of the Stouffer and add the base density of the Pictorico. They sort of cancel each other but I think there is a difference.

 

[nmp]

Now, in theory, your starting 1 atom of silver results into 1 atom of silver (or silver sulfide or combination) and if the reactions are efficiently performed 1 molecule of ferric ferrocyanide or Prussian blue.

:Niranjan.

Correction for that sentence (the chemical balance is off):

Now, in theory, your starting 3 atoms of silver results into 3 atoms of silver (or silver sulfide or combination) and if the reactions are efficiently performed 1 molecule of ferric ferrocyanide or Prussian blue.

See this thread for a full demonstration of this method:

https://www.photrio.com/forum/threads/additive-prussian-blue-toning-of-silver-based-prints.177686/