Pharoh Lith, a long-tray life ferrous-HQ paper developer designed for lith printing

[grainyvision]

Originally posted here: https://grainy.vision/blog/magic-lith-prototype-update-7-exf-pharoh-lith

“EXF1G” partial gold toned

“EXF1G” partial gold toned


Thanks to weird ideas and interesting non-photography chemistry papers, I’ve stumbled onto an extraordinary method of lith printing. I call it “Pharoh Lith” as a pun on ferro as in iron in a less common oxidation state. Pharoh Lith is a developer that basically breaks every rule in the book for a developer in order to exploit some exotic chemistry. The formula for EXF1 is as so:

• 2L of water
  
  
• Some shreds of steel wool (amount is not important)
  
  
• 3g of hydroquinone (can be in propelyne glycol or TEA. Either work just as well, but TEA may require pH adjustments)
  
  
• 0.8g potassium bromide (8ml of 10%)
  
  
• 1.5g of sodium hydroxide (30ml of 5%) (target pH is between 11.5 and 13)
  
  
• Preferably waiting 20-30 minutes before using this developer to allow the chemistry magic to happen (otherwise, first 2 or 3 prints will develop too fast and not exhibit good contrast)
  

Process (recommended)

• Rinse print before development (removes incorporated developers and ensures more even development)
  
  
• Develop. Typically takes 5-15 minutes depending on developer temperature, bromide content, and paper choice. Lithable papers will develop very quickly after the induction period
  
  
• Put into proper acidic stop bath; citric acid or regular indicator stop should be safe for this. Water bath can also be used but must be changed often. If the stop bath becomes alkaline it can cause iron fibers to seem to appear on the print and cause staining
  
  
• Rinse well under running hot water, at least 30s, to remove any stray fibers etc
  
  
• Fix in acidic (ie, not TF-4) fixer
  
  
• Rinse well
  
  
• Dip into acidic solution “to taste”. Strong solutions of oxalic acid will remove the superimposed iron image and decrease overall density on certain papers, but a short and dilute dip will help clear highlights without affecting other tones. A stronger >1% Citric acid should in theory remove any sludging from highlights with no tonal changes at all, though may be less efficient at clearing sludging and thus also affect archivability. More testing required. This acid dip can be skipped, but permanence will be especially unknown if not fully toned afterwards.
  
  
• Standard archival rinsing
  
  
• Tone image in an archival toner (gold or selenium)
  

When this is mixed the developer will quickly turn “dead developer brown”. This is exactly what you want. Basically the way this developer works is that the HQ quickly dies (forms photo-inactive benzoquinone) both from the iron in solution, and generally fast oxidation in such an alkali solution with no sulfite. However, if you’re patient and wait for the developer to die pretty much completely, an amazing thing happens. It comes back to life as a fairly stable developer. It’ll still be opaque dark brown so inspecting development progress is annoying, but the developer will work with consistent results over several hours, though it does get slower with more time. If you intend to try this prototype, I recommend buying some cheap pH strips. After the 30 minute warm up period, and occasionally with more prints and time sitting, the pH of the solution will decrease. If the pH drops below 11 you’ll get poor results that also develop incredibly slowly. Anyway, so the results of this are rather incredible AND universal. It works on every modern paper tested so far, though less-hardened papers normally capable of lith will require some chemical adjustments to slow down development (probably more restrainer, maybe less initial HQ).

“EXF1D” (before toning), Ilford Cooltone RC in Pharoh Lith from 645 ortho litho negative

“EXF1D” (before toning), Ilford Cooltone RC in Pharoh Lith from 645 ortho litho negative

The overall properties of the prints produced (of course still depending upon paper choice some)

• Fairly even development in most cases with proper agitation, even on hardened modern papers
  
  
• Somewhat warm-brown (depending on bromide content) shadows and extremely warm highlights and midtones, tilting more toward the red and golden colors rather than green.
  
  
• Some minor overall staining which will give a subtle peachy tone to the paper base. This can be partially removed with farmers reducer, but it is thus far impossible to remove it completely. Highlights will otherwise be extremely sensitive to both ferricyanide bleaching and farmers reducer
  
  
• Great amounts of contrast control via exposure over highlights and midtones, and a fair amount over lower midtones and shadows. ie, it feels pretty much 90% like lith printing for contrast control. Blacks will come in first, highlights and midtones won’t move after the induction period like in lith printing… but the shadows can tend to darken somewhat fast compared to how quickly blacks completely darken. With previous experiments though, this effect can probably be controlled some with restrainers like iodide and chloride.
  
  
• A long lasting and consistent developer. I used it for 3 hours and made 7 prints, and other than making pH adjustments and a bit of iron sludging (easily cured with a quick acid dip) the prints looked nearly identical, but with warmer blacks at the end due to bromide added by printing
  
  
• An iron image superimposed on the silver image in the shadows and especially blacks. This effect is why the image is so warm, and also why the permanence without toning is in question. The iron is most likely simple iron (Fe3) oxide, but if there is any iron hydroxide or other iron salts, then this can oxidize the silver over time. With selenium or gold toning though, the silver would be protected from oxidation. Gold toning is especially nice for this, producing blue highlights and midtones (if you go far enough) and warm brown shadows, if you don’t go for complete toning. If completely toned the entire image will be rather blue with shadows being closer to neutral. Note however, that this iron image can cause differences for bleaching. Typical ferricyanide bleach will not touch the iron image and any uncleanliness will be revealed by small specs of prussian blue. Ferrocyanide bleaching would in theory convert the iron image to prussian blue, allowing you to potentially shift the dramatic warm colors to insanely cold and blue colors after redevelopment of the silver. Note I haven’t tried that at this point, need to order some ferrocyanide first. The iron image will be rather weak and nowhere near black enough to use with complete bleaching and fixing of the silver
  
  
• Extremely fine grain at lower pH levels (11.5) and increasing grain in the shadows as pH is increased. Development also goes somewhat quicker and contrast is higher with a higher pH level.
  

“EXF1G” (before toning), MGV RC in Pharoh Lith, printed from 645 ortho litho negative

“EXF1G” (before toning), MGV RC in Pharoh Lith, printed from 645 ortho litho negative

Explanation of chemistry:

This is more of a best guess, but this is how I think the chemistry behind this works. According to a paper, the reaction of HQ with metalic Fe goes like so:

1. Fe is oxidized by HQ, producing Fe2+ and Q (benzoquinone)
   
   
2. Fe2+ ions will reduce Q ions to HQ, ie, it restores the developing ability. Fe2+ ions are converted to Fe3+ in the process
   
   
3. Fe3+ is made insoluble by the alkali solution and converted to Fe3+ oxide and Fe3+ hydroxide. Fe3+ can combine with HQ to once again produce Q.. but it seems like an alkaline solution makes it decompose naturally more quickly than HQ can decompose it.
   

Fomatone 133 FB in Pharoh Lith from 645 ortho litho negative, strong oxalic acid “bleached”

Fomatone 133 FB in Pharoh Lith from 645 ortho litho negative, strong oxalic acid “bleached”

Basically the iron functions as a “battery” for the HQ. You charge it with HQ in the solution, and it consumes pretty much all of it, then begins to release it but over a much longer time period. The paper referenced claims that HQ will still be in solution over 10 hours later, but at around 1/4 of the level originally put into the solution, and with a great curve when the HQ first begins being produced with it going from about 10% lower than initial amount to 50% lower over 2 hours. The paper only used a pH of 9 however, so using this significantly higher pH and plus introducing silver halides into the mix puts this into mostly uncharted territory. In addition to the Fe2+ regenerating Q into HQ, it also is a reducing agent and I believe will function as a weak developer. With a higher pH however this effect seems to mostly disappear, probably due to Fe2+ being unstable in alkaline solutions. This is why a pH of at least 11.5 is recommended. Below this level you’ll get a more normalized non-lith type of contrast and significantly more staining. The actual staining function of this developer I don’t really understand and can’t find any reference to. There are ancient ferrous based developers which produce a similar effect, but these are typically only ferrous sulfate or ferrous oxalate, and only within an acidic solution. In this process, the Fe2+ has nothing to become a complex/salt with other than the bromide, which I also believe is only possible in acidic solutions.

“EXF1D” partial selenium toned

“EXF1D” partial selenium toned

 

[adelorenzo]

Holy cow man you're on a roll here!

 

[chris77]

very interesting indeed! thanks for sharing

 

[esearing]

have you tried it as a second pass developer using bleach/reducer and redevelop?

 

[grainyvision]

have you tried it as a second pass developer using bleach/reducer and redevelop?

Someone else asked me about this in PM, here is what I said to them:

I haven't tried this yet, I mean, I just figured out this process actually works 3 days ago. It's currently designed for lith development, which can normally be done after bleaching to great effect, but requires somewhat different printing techniques like some over exposure to account for highlight losses. If you do try this after bleaching you'll want to make sure you rinse off the ferricyanide very well as in the developer it would form prussian blue, staining and spotting the print. I'm sure there are some differences that could be made if warm tones is the absolute priority and you don't care about the lith effect. I suspect a lower pH can be used (with a longer warm up period for the reaction to happen), and sulfite could be added which in solution I believe would create Fe2+ sulfate, a weak staining iron developer that is more stable at high pH levels. Note that Fe2+ sulfate is "natural" but also somewhat dangerous. It's the iron used in iron supplements which can of course cause problems with too much ingestion, though there should be no effect by inhalation and minimal absorption through skin. Either way, I wear gloves with all development. I got a small drop on my arm and it gave a minor burning sensation but didn't seem to actually leave any chemical burn. The developer itself will have a distinctly metalic smell that's not offensive. If you try it out I'd definitely be interested in hearing about it. If you don't have access to raw chemicals, I suspect that a similar developer to pharoh can be made by simply adding iron wool to a Lith A+B developer, with extra B to get the pH right, though a hydroxide based lith developer will probably be more stable than a carbonate based one. Carbonate will form Fe2+ carbonate and in my tests gave worse results.. Also I suspect the paper base staining effect will happen with redevelopment in this, ie, peachy orange borders

 

[grainyvision]

I accidentally posted an update to this in PM, woops. Either way, I think I've found a contender for a pharoh lith formula without the iron sludging and iron image bits (which can be added later in a more controlled way I think anyway). The formula I used is as so:

EXF4 formula:
* 2L water
* 4g ferrous sulfate heptahydrate
* 60ml of triethanolamine (TEA)
* 12g of potassium carbonate (from a 20% solution, 60ml)
* 0.6g potassium bromide (6ml of 10%)
* 0.25g of sodium hydroxide
* 2g of hydroquinone in propelyne glycol 10% (20ml)
* Final pH is between 10.5 and 11

I actually tried to do a print before adding the hydroquinone. It developed an extremely weak image after 10 minutes which mostly disappeared after fixing and severely stained the paper. There was also some metallic iron present in the solution at this point. I then added the hydroquinone and the metallic iron slowly dissolved away. There was still some minor sludging problems for 1 or 2 prints afterwards, but after that it seemed to have minimal sludging and minimal iron image, but does require a good rinse in running water to unstick any microscopic iron bits. Dipping into oxalic acid seemed to have no effect on image either before or after fixing. There is still some minor orange staining. The exciting thing about this developer is that it continued working at similar activity levels for 2.5 hours and over 16 prints. The bad thing is that I think these components are unbalanced. I do get delicate highlights typical of lith printing, but midtones develop too quickly in comparison to black levels. This works fine for when you want a higher contrast print, but does poorly with low contrast as there is a lot of midtones which all grow dark before a proper black level is set. This developer also didn't work well with lithable paper. The entire thing would develop too quickly without a significantly faster black level development.

The exact chemistry behind this involves many interactions and a cycle of reactions.. This is my understanding from 2 different papers that I used to figure this out

* HQ (hydroquinone) easily oxidizes in alkali solution to Q (benzoquinone) which is then photographically inactive. HQ also produces a semiquinone upon reduction of silver halides which is responsible for infectious development effect. The semiquinone is extremely reactive, but also somewhat stable in an alkali solution. Both the semiquinone and HQ will oxidize Fe (metallic iron) and Fe3 (ferric oxide) to produce Q and (sometimes?) produce an irreversable polymerization of HQ which is not photographically active
* Ferrous(Fe2) sulfate easily oxidizes to ferric sulfate and/or ferric hydroxide or ferric carbonate in alkali solution. It is photographically active, but only very weakly in alkali solution (typically used in acid for alt processes). Fe2 will reduce Q back to HQ, producing Fe3 in the process.
* Ferrous hydroxide is a strong reducing agent and I believe the primary agent responsible for the iron image effect of EXF1, however it is just barely soluble in alkali solutions, so it tends to precipitate. It is quickly produced by reaction of Ferrous Sulfate with hydroxide, however it is somewhat unstable and will oxidize to ferric hydroxide, which is otherwise inactive.
* TEA is the big thing to complete this cycle to form something metastable. TEA has a very strong affinity to grab onto Fe3 ions and reduce them to Fe2 when in a strongly alkali solution (>9pH). It has an affinity to also grab onto Fe2 ions and convert them to Fe, but with less preference than Fe3->Fe2 (since it must remove 2 electrons instead of 1 in the former case). I believe it will even tear apart fairly stable compounds like ferric hydroxide in order to reduce it to a ferrous ion and hydroxide and form a complex in solution. It also I believe will form complexes with nearly all iron compounds aside from metallic iron, though apparently does not prevent the ions from interacting with HQ.

The ideal end result of this is the HQ is constantly dying and regenerating and will thus remain at a fairly constant level, and a decrease from development will recovery fairly quickly to the original amount. The problem is that these 3 variables are far from simple to balance for ideal lith results. I believe the lack of midtones right now is due to too much HQ being kept alive in solution. In theory with this cycle the HQ that is put in will slowly decrease by irreversible polymerization, but otherwise is constantly being regenerated, hence why the developer continued working at about the same level and speed for 2.5 hours despite containing no sulfite, and despite not seeming to form hydroquinone-monosulfate. I believe the TEA content is ultimately the determining component for tray life, while sulfate content determines how fast the HQ regenerates. HQ content ultimately determines how fast the TEA is used up due to constant regeneration by ferrous sulfate. A simple 500ml beaker test with 1g HQ, same pH (only carbonate), 1.5g of ferrous sulfate, and 30ml of TEA seemed to stay alive for 4 hours, was stable in activity level for 1.5 hours, and dropped off in activity quite severely after 4 hours (going from 35s to 1.5m for developing a fogged strip to black). The beaker test solution seperated after 1 hour of sitting into an orange top layer and green-grey powder at the bottom. After 2 hours the powder content was significantly less and had more of a grey color without the green. The top orange layer also darkened and became somewhat red. After 4 hours the powder layer was nearly gone and the top layer was extremely dark reddish-brown and difficult to see through.

Attached picture is from print #8, about 1.5 hours in, printed with a fairly low exposure for a high contrast look

 

[esearing]

would a gram of Metol added late in the mixture provide an adequate developer action as the HQ is dying? Since HQ regenerates the Metol it might give that boost in the shadows and mid tones. Metol may not be suitable for Lith since it may alter the grain size or cause too much fog.

 

[grainyvision]

I don't think metol would produce a lith effect, but if using it as a toning developer I don't think it would hurt. Sulfite could also probably be added. I'm curious to reformulate this as a normal developer rather than for lith printing, as I'm getting quite frustrated with the entire process and how delicate it is.

In other news, did a A/B test run of a simple HQ developer with a surplus of TEA and with/without ferrous sulfate. The without version lasted longer, both lasted a long time (6+ hours), but could not produce infectious development. I assume the TEA is scavenging the semiquinone and interfering with the infectious development effect somehow. Incredibly frustrating and basically puts a dead end to my ideas on how to improve EXF4. Will probably go back to EXF1 to see if I can improve the lith effect, and reformulate it to not be a lith developer (and hopefully be much more stable). Honestly though after cleaning a ton of iron oxide from my sink I'm a bit tired of the iron developer bit. Had to use the Iron Out I had on hand for chemistry experiments to actually clean for once (and it works really great for removing rust, as the name implies heh)