Question about home made "Rodinal"

Fisrt: as far as I'm aware, I was the first to offer the name it has now. I gave it the name Parodinal, punning on two properties: it is made from PARacetamol, as they call it in most of the rest of the world, and it is a "PARODy" of the real stuff.

The 72 hour stand time is to allow time for the lye to cleave the acetyl groups off the acetaminophen to convert it to p-aminophenol, which is a MUCH better developing agent than the n-acetyl p-aminophenol that acts as a pain reliever.

However: you got the wrong thing. You got the PM formula -- the diphenhydramine is an anihistamine, used in this formula for its sedative properties. I don't know what if anything it will do in the developer. I recommend buying the plain 500 mg "non-aspirin pain reliever" with the warning that it contains acetaminophen and to see the label for more warnings (apparently this stuff isn't as safe as it was thirty or forty years ago). Your price wasn't bad, though; same dollar store should have the plain tablets for the same or lower price per tablet.

Donald Qualls said:

Fisrt: as far as I'm aware, I was the first to offer the name it has now. I gave it the name Parodinal, punning on two properties: it is made from PARacetamol, as they call it in most of the rest of the world, and it is a "PARODy" of the real stuff.

The 72 hour stand time is to allow time for the lye to cleave the acetyl groups off the acetaminophen to convert it to p-aminophenol, which is a MUCH better developing agent than the n-acetyl p-aminophenol that acts as a pain reliever.

However: you got the wrong thing. You got the PM formula -- the diphenhydramine is an anihistamine, used in this formula for its sedative properties. I don't know what if anything it will do in the developer. I recommend buying the plain 500 mg "non-aspirin pain reliever" with the warning that it contains acetaminophen and to see the label for more warnings (apparently this stuff isn't as safe as it was thirty or forty years ago). Your price wasn't bad, though; same dollar store should have the plain tablets for the same or lower price per tablet.

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Thank you Don. And $1 is not going to break the bank. I was just curious and will still try to do this, making believe that the diphenhydramine will be inactive with this developer (wishful thinking). It is worth the gamble. - David Lyga

Diphenhydramine is an antihistamine, so it looks like you bought an anti-allergy combination drug instead of plain old acetaminophen/paracetamol.

You may have to experiment, but I don't think it's safe to assume that the diphenhydramine won't have an effect.

Donald Qualls said:

(apparently this stuff isn't as safe as it was thirty or forty years ago).

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We've learned since then that a person can overdose on acetaminophen/paracetamol and destroy the liver. There are many cases of people causing fatal damage through overuse of these products, without intending to do so. So the warnings aren't trivial.

It's safe in the recommended doses over the recommended length of time. Higher doses or longer dosage periods increase the danger. At a point, you can cause enough damage that your death will be days or weeks away and there is nothing a hospital could do for you.

David Lyga said:

Each caplet has 500mg of Acetaminophen PLUS 25mg of Diphenhydramine HCI. Does this second ingredient do anything positive or negative to the Rodinal experiment?

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It's a chemical that has found no use in photochemistry. Be the trailblazer and let's know what you discover.

David Lyga said:

I do have more questions regarding this "do it yourself" Rodinal. First why is it called "PA" Rodinal? Second, why must is be left untouched for 72 hours after mixing and before use? And, today, I bought 24 caplets at the Dollar Tree for $1. Each caplet has 500mg of Acetaminophen PLUS 25mg of Diphenhydramine HCI. Does this second ingredient do anything positive or negative to the Rodinal experiment? - David Lyga

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Because it’s made with Paracetamol. It wouldn’t be active by the looks of it as a developing agent. But it’ll add some sodium chloride to your mix by reaction with the base which may affect your formula so what, but unlikely since it’s so much less than the paracetamol amount. Cheapest paracetamol I’ve seen is around 80 cents AUD for the same amount at supermarkets.

and the idea is to let it sit to make sure hydrolysis is carried to completion before using it, so to reach “full strength”.

PhotoJim said:

You may have to experiment, but I don't think it's safe to assume that the diphenhydramine won't have an effect.

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It won't, because it is not a redox active compound.

Don't waste your film trying it.

Raghu Kuvempunagar said:

It's a chemical that has found no use in photochemistry. Be the trailblazer and let's know what you discover.

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I mixed a total of 50mL today. I am waiting three days for the 'fine wine' to become of value. I made 50mL of 'Rodinal" this way:

six 500mg caplets of the Dollar Tree acetaminophen. This is 3 grams of the acetaminophen. I got 24 caplets for a whole $1!!! Yes, these caplets also have the diphenhydramine (25mg each caplet).

5 mL (yes, by volume) of sodium sultife, anhydrous.

8 mL (yes, by volume) of sodium hydroxide.

WTM 50mL.

I crushed the caplets and used very warm water (which became yet warmer after the sodium hydroxide was added. About three hours after I mixed this, I put a tiny edge of B&W photo paper into it and it became immediately jet black. I will try film on Sunday, after it becomes 'vintage'. - David Lyga

I know, already, that there is a collective angst over my measurement method, but I am counting on this to work.

Andrew O'Neill said:

It's moments like this where I miss PE!

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Why? When you have someone far and away more brilliant, engaging, (and too often, deranging)? - David Lyga

David Lyga said:

Why? When you have someone far and away more brilliant, engaging, (and too often, deranging)? - David Lyga

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You're right. Once again, my humblest of apologies!

If the film turns black almost instantly in the concentrate, that's good. Once it turns a little pink, it's ready (doesn't always take three days).

Donald Qualls said:

If the film turns black almost instantly in the concentrate, that's good.

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It's a piece of photographic paper that turned black. If it is a paper that contains incorporated developer, then OP's test confirms only the strong alkalinity of his Parodinal concoction. He might want to test again with a piece of film.

David Lyga said:

I put a tiny edge of B&W photo paper into it and it became immediately jet black.

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OK, I took Donald Qualls's advice and did not wait the three days. It is pinkish orange and looks absolutely disgusting. But it works, and seems to work well. My exposure and development data for this picture are:

I used a VERY old Arista 50 (sold by Freestyle more than a decade ago, and I believe it to be rebadged Pan F+). EI that I chose was 32, so it has not lost speed. In fact, I think the negative is even slightly over exposed! Dilution was 1 + 49 and the temperature was 75F. I merely cut about two inches of film from the spool, inserted into the back of my Chinon CS (the film was placed a bit skewed, as you can see from the picture of the negative's borders). I developed the negative in a film can and constantly turned it around and around for the development time of 7 minutes. My precise working solution was .25 mL of "MY RODINAL" plus 12.25 mL water. This agitation method is somewhat similar to the Jobo method whereby constant agitation is done. The day in Philadelphia was very overcast and about 8:30 AM. My exposure was f4 and 1/30th. Again, it seems slightly OVERexposed. Maybe the film is actually about 50 or 64 in speed which says a lot for the longevity for old, SLOW film.

I have a very cheap digital camera so everything might not look extremely sharp. However, that negative is razor sharp and I tried to find grain but there was none to see.

Having said all of this, I stress that I have NO IDEA how long "MY RODINAL" stock solution will last. I highly recommend (HIGHLY RECOMMEND) that before drawing any liquid from the stock, you shake that solution so that you will be pulling representative components in the liquid. Again, that liquid looks truly disgusting.

I made a total of 50 mL of stock solution using the formula which I had posted earlier. I warn you that if you get any of this ugliness stuff on anything, it will stain mightily once dried.

The cost for me to make the 50 mL of "MY RODINAL" was about 40 cents. This, times ten would be $4, which compares favorably with $16 for the genuine article (since that comes in 500 mL sizes). The other ingredient along with the Acetaminophen, Diphenhydramine, seems to be inert as regards photo developing. - David Lyga

David Lyga said:

Diphenhydramine, seems to be inert as regards photo developing

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No surprise there, as I said. At most it will be acting as an additional accelerant due to it possessing a basic group, but given the very minor amount present and that you are already using excess sodium hydroxide (a much stronger base), this effect will be essentially nil.

All the undissolved solids in your mixture will probably be the excipients used in the pills.

Yep, that looks like a success. Generally, the slower the film, the less it fogs as it ages, and less fog == less loss of speed due to age.

Get the plain acetaminophen next time you buy, and good to go. As suggested earlier, plain APAP (acetaminophen/paracetamol) is almost certain to be cheaper per dose than that PM formula.