There is a way to add ascorbate to Rodinal working solution that seems to give somewhat finer grain without disturbing its other characteristics. This is described in www.unblinkingeye.com somewhere. Briefly, mix 1 teaspoon ascorbic acid powder with 1/2 teaspoon sodium bicarbonate in a small amount of water. When effervescence ceases, add 20 ml Rodinal concentrate and water to 1 liter. Treat the mixture as 1:25 Rodinal. This essentially forms a sodium paraminophenolate-ascorbate developer that you can play with while you're having phun.
I have a tendency to get carried away having phun instead of taking photographs. I'll out the ascorbate idea but after I've tested the EZ KOHnal I made.
One question, why not just add Sodium Ascorbate? Some health food stores seem to have it.
No reason except it doesn't seem to keep as well as the acid, and some recipes call for the acid. If you decide some day to play with stock solutions in glycol or TEA, the ascorbate will not dissolve but the acid will. I find it more convenient to have a container of ascorbic acid and one of baking soda than one of ascorbic acid and one of sodium ascorbate. Besides, when things don't go right, the baking soda helps the ensuing gastric disturbance, so I need the baking soda anyway.
Originally Posted by chakra
I let the original batch of KOHnal sit for a couple of days. When I came back the color was darker and the pinch of precipitate was gone. This was in a light-tight and air-tight 50ml falcon tube.
So I thought, I'll remake a 50ml batch and see what happens. If I follow the amounts from your formula and let the solution sit for a day, I get a 50ml solution that is the color of Agfa Rodinal (light pink in the beginning, turns darker after a day) and has a whitish pink precipitate of about 4 ml volume at the bottom. More importantly, the pH is at 11.9 which is exactly what you get. I brought the pH upto 12.
I've developed a roll of Tri-X in commercial Rodinal which is drying now and will develop a strip of 10 frames of Tri-X from the same batch to see how it looks. We should have a comparison soon.
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Here is a sample from a 35mm Tri-X 400 strip rated at 400 and developed for 10 minutes at 20 degrees celcius. Agitation was for the initial 30 seconds and 2 inversions at the beginning of every minute from then. Water Stop. Fresh Kodafix.
Scanned at 4000 dpi in 48bit Color using a Nikon LS-50 at 4000dpi and resized to 15%.
I was found two different formula for EZ-Rodinal
1st early version found here: http://www.apug.org/forums/forum37/2...titutes-4.html
Start with 700 ml water at room temperature.
Add 170 grams of anhydrous sodium sulfite, 14 grams sodium hydroxide, and stir till dissolved. Warming it a little won't hurt. Add 40 grams p-aminophenol (not the hydrochloride). It will not all dissolve. Add water to make 1 liter. When you transfer from the mixing vesel to storage, do not filter out the sediment. Use it like AGFA Rodinal.
2nd (latest) version from EZ-Rodinal article http://www.apug.org/forums/forum223/...z-rodinal.html
To 400 ml water, add:
85 g anhydrous sodium sulfite.
40 g p-aminophenol base.
Stir well. Add
13.8 g sodium hydroxide or 19.2 g potassium hydroxide.
Add water to make 500 ml.
rewrite this formulas for 1l concentrate:
Sodium sulfite 170g
p-Aminophenol base 40g
Sodium hydroxide 14g
Sodium sulfite 170g
p-Aminophenol base 80g
Sodium hydroxide 27.6g
easy to see that 2nd version have twice amount of p-Aminophenol. Compared to known Rodinal formula from http://www.digitaltruth.com/data/rodinal.php
p-Aminophenol Hydrochloride 50 g
Potassium Metabisulfite 150 g
Sodium Hydroxide 100 g
Cold water to make 1L
while we mix all ingredient reaction describes next formulas
K2S2O5 + 2NaOH = K2SO3 + Na2SO3 + H2O
C6H4OHNH2.HCl + 2NaOH = C6H4ONaNH2 + NaCl + 2H2O
MW(C6H4OHNH2.HCl)=145.59, so formula contains 50/145.59=0.343M of p-Aminophenol Hydrochloride. For PAP base MW(C6H4OHNH2)=109.13. and amount of base will be 109.13*0.343M=37.48g. This is near the 50g in 1st version of EZ-Rodinal.
Amount of K2SO3+Na2SO3 is 1.35M. We need 1.35M*MW(Na2SO3)=1.35M*126.04=170g of Sodium sulfite. This is also same as in 1st version.
So my question - is the 2nd version of EZ-Rodinal correct?
I won't go into the details of the rest of the discussion, but wanted to make two quick comments.
1) I made the A&T version, but only after I had decided to dissolve the p-Aminophenol in hydrochloric acid to be sure I had the hydrochloride version. The rest went well, and the developer worked exactly as it should. It seems laborious, but given the amount of developer it makes for fairly little trouble and money, it is well worth it.
2) I have since settled on parodinal, which works exactly the same and is a lot cheaper and easier to make still. The reason it is cheaper is because paracetamol is available in bulk quantity for next to nothing via pharma suppliers, while 4-aminophenol is usually special order as an AR grade lab chemical. If you haven't done parodinal before, I must urge you to give it a go and decide for yourself. For a very straightforward, foolproof method, look up my thread with the attached excel calculation sheet. If it fails you, I'll make you a 1 litre bottle and keep it for you until you visit South Africa. It will still be good 20 years from now.
Dorff, a link please. Can't find it. TIA
look up my thread with the attached excel calculation sheet