Fine grain developer from Paracetamol/Tylenol

[ME Super]

Cars rust faster in salt water than they do in fresh water. Salt is an oxidizing agent, not a reducing agent. Silver halides need to be reduced to metallic silver, so you need a reducing agent, not an oxidizing agent. That's why salt isn't used as a developing agent in silver halide photography.

 

[Alan Johnson]

A first result from a new formula:

Solution A:
Dissolve 5g sodium hydroxide in 90ml water, add the contents of 16 capsules (8g) of Paracetamol/Tylenol.Stir with gentle heating in a stainless steel pot,filter through cotton wool, make up to 100ml.
Store in a 100ml sealed bottle 7 days at room temperature to complete the hydrolysis and make the primary developing agent (p-aminophenol).
Note, sodium hydroxide is caustic, hazardous:
http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/sodium_hydroxide.html
It is sold as Lye or as Caustic Soda.

LS-1c
Water.............................................................800ml
Ascorbic acid (vitamin C powder).........................15g
Solution A above..............................................100ml
Sodium Carbonate anhydrous..............................50g
Water to.............................................................1L
Filter 2x through cotton wool.
pH=10.4 +/- 0.1 Develop for Xtol 1+3 time from massive development table at digitaltruth .com

Sodium Carbonate anhydrous may be replaced by Washing Soda.
In the US, Arm &Hammer Super Washing Soda is close to monohydrate so take 50x1.2=60g Soda.
In the UK, Washing Soda is usually the decahydrate so take 50x2.7=135g Soda.

After 16 days in a 1L glass bottle the pH was still 10.4.The developer still worked,see attachment.
I hope to report later how the developer keeps.

Grain obtained was similar to that with Beutler developer.The large grain is because the specification that all ingredients should be obtainable from local shops means sodium sulfite cannot be added.

 

[Alan Johnson]

I goofed in the post above, the development time should be the same as Xtol 1+0, not 1+3.
Now I just report that in a part full sealed bottle the developer is keeping well, at 52 days old its pH was 10.2 +/-0.1
Attached is a pic developed in it after 54 days.

The simplest explanation of what has been reported in the above posts:
Paracetamol/Tylenol is hydrolysed by the caustic sodium hydroxide (handle with care) producing p-aminophenol derivatives.
p-aminophenol is superadditive with ascorbate and regenerated by it,
ascorbate is oxidized to dehydroascorbic acid,
dehydroascorbic acid is orange,
dehydoascorbic acid is a stronger acid than ascorbic acid and tends to cause a fall in pH unless well buffered.
I don't think too much is public about ascorbate chemistry, it is post Film Developing Cookbook and other technical texts.

 

[Alan Johnson]

Continuing with this p-aminophenol/ascorbate formula,I noted that p-aminophenol/hydroquinone was used as early as 1902, see esp p197, Rodinal-Hydrokinone:
https://archive.org/stream/cu31924031226065#page/n0/mode/2up
Later p-aminophenol/hydroquinone was used as a tropical developer,see Digitaltruth.com formulas for Kodak D-13.
With more sulfite it was found in Ilford ID-44 ,I believe superseded by Perceptol.
Thus p-aminophenol was generally replaced by metol which is more active.
One would expect metol/ascorbate to be a more active developer than p-aminophenol/ascorbate tested here.

My LS-1c has now developed 7 films and 600ml of the original 1000ml remains in the bottle.Oxidation has occurred as the pH has fallen from the initial 10.4 to pH=9.9 after 94 days.
It still works, see attached pics.
It appears the oxidation product of ascorbate is quite a strong acid to cause this pH drop.The solution has a distinct orange tinge.I will continue to monitor the pH.

 

[Trask]

Very interesting, Alan. What if we cheated on the rules a bit, and allowed that we had some sodium sulfite available. Could one just add a small amount, maybe 20g/liter, without otherwise affecting the performance of the developer?

 

[Alan Johnson]

The chemistry of Metol (free base= 4 methylaminophenol) is discussed in many books, the chemistry of p-aminophenol is not. This is because Metol replaced p-aminophenol early on.
If you replace Metol by p-aminophenol based on the assumption that the chemistry may be similar it's really a research project.
Metol/Ascorbate/Sulfite is known to work.

 

[Alan Johnson]

This developer LS-1c , made from ingredients bought at local shops, is now 6 months old. It has been kept in a half full glass bottle for most of its life and has developed 9 films plus some test pieces.
It still works after 6 months, I developed a test film in it.The pH was originally 10.4, after 3 months it fell to 9.9 and now after 6 months it is 9.7.
A separate batch kept in a full sealed glass bottle had a pH of 10.2 after 5 months.
This strongly suggests that the fall in pH is due to the oxidation of ascorbate by the airspace in the bottle. A relatively large ascorbate concentration to start off with means there is enough which is still not oxidized to keep the developer working and a relatively large concentration of sodium carbonate has kept the pH high enough for the developer to still work.

LS-1c uses ascorbate to regenerate p-aminophenol.A correspondent pointed out to me that a certain Charles Thatcher took out a patent involving the use of hydroquinone to regenerate p-aminophenol nearly 100 years ago:
https://www.google.com/patents/US11...a=X&ei=64Q9U-6sEYyp7AaMooDAAw&ved=0CDcQ6AEwAA
This combination has more or less fallen into disuse but still a formula exists as Kodak DK-93 general purpose developer.

LS-1c is really only of interest if proprietary chemicals are not available, IMO, as it provides a low film speed, EI<50 (Xtol EI=100).At 1+3 dilution it works as a paper developer but the results are a bit flat compared with a proprietary developer. In complete absence of photochemicals the film can be slowly fixed in table salt solution:
(there was a url link here which no longer exists)

As noted before, care should be taken with the caustic sodium hydroxide:
http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/sodium_hydroxide.html

 

[Alan Johnson]

LS-1c, post 28, is now 14 months old. Since the 6 months report above it developed 2 more films and was then left in a half full glass bottle.
At 14 months I developed a test film , it came out very thin, barely visible images, except for slight darkening of the film leader.
The pH was originally 10.4, after 3 months 9.9, after 6 months 9.7, now after 14 months 9.6.
It has gone inky black, even stains the stop bath.
Inky blackness is usually associated with p-aminophenol oxidation products so I suspect that all the ascorbate is oxidized and some of the aminophenol as well.
Hence it is suggested that the shelf life be considered as 6 months only.

 

[Gerald C Koch]

P-aminophenol and metol are very similar as developing agents. Unlike metol p-aminophenol does not cause allergic dermatitis. The problem with p-aminophenol is its instability in air. It rapidly oxidizes in crystalline form and is thus only used in liquid developers like Rodinal. The hydrochloride salt has greater stability than the free base but is still less stable than metol. The main difference between the two developing agents is that p-aminophenol is a bit softer working than metol and produces somewhat less contrast when used in typical developer formulations like D-76 or DK-50.