I referenced this thread a lot in devising my own lith printing formula. It seems to work well with reasonable tray life, but unfortunately short shelf life. The sulfite in my acidic part A works a bit too well and turns into mildly pressurized sulfur dioxide. The developer works great with no change in color over several months, but the sulfite ratio is wrong and inconsistent over time. ie, initially you need to add no sulfite. Later you need to add 0.2-0.8g depending on how old the part A is.
The developer is named ModernLithEZ. Instructions below (numbers in [] brackets are for doubling, for my own reference)
Part A:
Start with 80ml[160] of hot distilled water (distilled water is absolutely necessary here!)
1ml[2] triethanolamine 99% grade
0.1g[0.2] salicylic acid
5g[10] sodium sulfite
1g[2] boric acid
10g[20] ascorbic acid
11g[22] hydroquinone (not all will dissolve)
Top to 200ml[400] with hot propylene glycol
This may require some heating to dissolve all of the hydroquinone
Part B:
Start with 140ml[280] of cold or room temperature distilled water
10ml[20] triethanolamine 99%
8g[16] sodium hydroxide — DANGER
1.2g[2.4] potassium bromide
100g[200] potassium carbonate, anhydrous — DANGER
Top to 200ml[400] with cold distilled water. The solution should clear up significantly.
Part C — A simple 1% solution of polyethylene glycol 3350
200ml of water
2g of PEG-3350 (sourced in the US as “MiraLax”)
Part D (optional) — A simple 5% potassium bromide solution
100ml water
5g potassium bromide
Usage: Start with 30ml of part A added to 900ml of water, followed by 30ml of part B and 1ml of part C. Top to 1L with water. Ratios can be adjusted wildly to tune results and to optimize for different papers. Use as a lith developer, with over exposure of 2 stops or more to vary contrast, and pulling the print when it looks right.
This formula is an especially difficult challenge as my goal is not just to make a reasonable homebrew lith developer without formaldehyde yet having good tray and shelf life, but to also allow this developer to work on modern materials. The key factors I've learned is that the ratio amount of bromide to other components must be fairly low. Modern materials, especially RC papers, seem to suffer from the "lith bromide bleaching" effect. This is an effect where bromide+hydroquinone in low sulfite solution can actually render latent image centers undevelopable, meaning even with re-exposure it will not develop. I've observed this effect many times in figuring out these formulations. The effect is time and bromide sensitive... so, if the developer is too slow the effect can happen as well. It's a very difficult one to figure out... Regardless, as-is, this formula works for decent tray life when fresh. It doesn't work perfectly with as many papers as I'd like (Ilford MGFB and Adox FB papers give weird "pepper balls") but it works with a decent subset of them.
Months later, I'm now looking at a refresh of this formula to simplify it and try to figure out a method of flattening this sulfite "evaporation" problem. The part A obviously is a bit too acidic but would benefit from a bit more sulfite. I'd like to exclude hydroxide and TEA from part B, considering if I should move the bromide from part B to part A, etc.
Specific notes in this formulation that should be inspiring regardless:
* propylene glycol isn't "necessary" here, most manufacturers use diethyl glycol as it's cheaper. Neither seem to be photo active. The key benefit is propylene glycol will have less oxygen solubility than water, and hydroquinone is more soluble in it than water
* Boric acid was used on the recommendation in this thread, to prevent fog. I'm not 100% sure it's actually beneficial here.
* The part C is the real key innovation here. I believe it can be added in small amounts to nearly any homebrew developer to cure the "homebrew lith" look that causes LD20 and similar developers to give strikingly different results from any homebrew lith developer.
* The TEA is used here in part A because it is a chelating agent, same for salycilic acid. It should preserve the ascorbic acid (though it seems sulfur dioxide will destructively preserve ascorbic acid too)
* The TEA is used in part B in a higher amount to boost alkalinity slightly forming a weak buffer. It also potentially gives warmer results by being a silver solvent, and it is a preservative. It does react with hydroquinone oxidation products in some non-determined way. A TEA+hydroquinone+water mixture without sulfite will be transformed upon standing several hours into a normal contrast print developer upon adding carbonate. I've seen absolutely no research of this reaction and haven't studied it much though
* I'd prefer to avoid hydroxide for both safety and stability reasons in the part B. It was used because I was nearing the solubility limits on carbonate for neutralizing the ascorbic acid, and either way this much carbonate becomes a bit expensive
* The ascorbic acid is confirmed to act as a good preservative for hydroquinone. It becomes active in a way resembling weaker hydroquinone above pH 12
* For modern materials specifically, low sulfite and low bromide amount seems to be the key, but also slightly higher alkalinity. Very much sulfite at all gives obvious differences to dmax on RC papers
That being said, anyone on this thread have any ideas for this formula?
Studying the EasyLith MSDS, it is surprisingly sparse. Key things I think:
* Sulfite is in both part A and B (notice "burning emits sulfur dioxide" warning, typical of sulfite containing solutions)
* Boric acid I believe is a poison and thus must be listed on an MSDS, but it is not listed in either part A nor B. Borax is also not listed. Apparently this effect was not important for EasyLith
* A non-toxic preservative, like ascorbic acid is likely in part A. There is no indication of how the pH of 5.5 is reached, nor how the ascorbic acid is kept stable if that is the case. Maybe there is some non-toxic but more stable cousin to ascorbic acid used here?
* The carbonate in part B is only up to 40%. This rules out using a significant amount of ascorbic acid, unless they balanced it out with ascorbate and/or partially neutralized the acid. Otherwise 40% solution added in equal ratios would likely not bring pH up enough