A few paRodinal questions.

glpozza · Jul 23, 2014

Hello. I'll attempt to make a batch of paRodinal next week, but there are some subjects that i believe aren't really clear on the other threads.
I can get powdered paracetamol. Will it be a significantly improvement over crushed tablets? The powdered version is 3x more expensive.
If I can use a 50% solution of sodium hydroxide, should I use twice the amount of the anhydrous version? (i.e. 20g anhydrous would become 40g liquid)
Some users sugest reducing sodium sulfite would result in a finer grain. Anyone ever tested it?
Several images seem to have their contrast corrected in photoshop after the 1:100 stand development. Since I intend to wet print, could someone point to "straight" images so I know what to expect?

I have a fairly good experience in b&w lab, using mostly D76, HC110, microdol and TmaxRS as film developers, but I've never mixed a developer from scratch before. Nevertheless, I've been printing in some alt. processes (gum and carbon), so handling chemicals isn't really an issue.

Thank you all in advance.

Rudeofus · Jul 23, 2014

A 50% solution of NaOH is a liquid that contains 500 grams of NaOH per liter. This means you should add 40 ml, not 40 g of NaOH 50% solution if you want 20 g NaOH.

As far as these "doing/adding/changing this will give finer grain" things go, you will have to test yourself. Too many reports are wildly inaccurate, outdated, overly hyped, or based on poor test procedure or unintentional underdevelopment.

Likewise, you can not rely on scanned results to evaluate contrast, because scanning software does all kinds of "smart" adjustments that you have no control over. Modern photographic multigrade papers can handle a wide range of negative contrasts, so you shouldn't worry unless your negs look waaaay off.

Xmas · Jul 23, 2014

Rodinal or a clone is normally easily available simpler to buy a bottle.

You don't need to use it 1+100 unless you want flat negatives, most people use 1+7, 1+25 or 1+50.

The sulphite is so low a level at working dilutions you would need to increase it for more solvent effect but the concentrate is saturated normally so not practical.

If you don't have safety googles dont handle sodium hydroxide. One mistake and you need a dog.

Rodinal was only recommended for slow and medium speed films if you want fine grain use microphen or ID-11.

glpozza · Jul 23, 2014

Thank you for your answers.
The only developer I can find in Brazil nowadays is D76, and for around $20 a liter, so I'm looking for a better alternative.
The safety googles are ready.
Should I invest in the powdered paracetamol or it's just a waste of money?

Xuco Martin · Jul 23, 2014

If you want crystal clear Parodinal is ok to buy powdered if you really miss accounts is extremely cheap due to its high concentration although the 1:50 dilution
I use it a lot and with very good results, if you want more fine-grained sulfite add a little water you use to dilute.

Se você quer cristalina Parodinal é ok para comprar pó, se você realmente perca contas é extremamente barato, devido à sua alta concentração, embora a diluição de 1:50
Eu uso-o muito e com resultados muito bons, se você quiser sulfito mais refinado adicionar um pouco de água que você usa para diluir

(there was a url link here which no longer exists)

David A. Goldfarb · Jul 23, 2014

I made a batch once just out of curiosity using expired uncoated generic acetaminophen tablets that we would have tossed out anyway, and I was surprised at how good it was and that it worked with the same development times as I would use with commercial Rodinal. I still use it occasionally for slow to medium speed films usually, and the concentrate seems to last forever like Rodinal. As long as you can trust your pharmacy to supply the what it says is in the bottle, and it's cheaper than the powdered kind, I'd just buy the cheap stuff, or check the back of the medicine cabinet for the extra-large bottle of 500mg tablets you probably bought 10 years ago, because it was such a good price, and you thought you were going to have more headaches than you did.

glpozza · Jul 24, 2014

Sadly I never had headaches...
I found another place with a better price for paracetamol, so I'll try it with the powder.
Since most of the threads about parodinal seem to lack the results, after I get all the chemicals and process a test film, I'll get back with the results and the formula used. It may take 2 or 3 weeks.
Thank you.

Xmas · Jul 24, 2014

Dead Link Removed

Zorkicat is an APUG member...

pdeeh · Jul 25, 2014

Forum member dorff has done lots of work with paRodinal, and he created a calculator spreadsheet to help people optimise their recipes using different ingredients.

It can be found here: (there was a url link here which no longer exists)

It's not particularly user-friendly to those of us without a background in chemistry, but it is very useful nonetheless.

I make up a batch every few months because it is very cheap indeed, and it's handy to have a quite all-purpose developer on hand when I'm messing about (I use it for both film and paper negatives); for anything I want to be sure is "properly" developed in Rodinal I have a bottle of RO9, but tbh if I look at films developed in RO9 and those developed in my paRodinal, I can't tell the difference.

glpozza · Sep 7, 2014

And the unexpected: I guess the lab sold me something else as paracetamol. I mixed to the hidroxide solution and it just sank. Wouldn't mix nor react. Had to Try again using tablets, so nothing new to report other than the obvious "it is working". Thank you all for the information and links to other threads about this developer.

timor · Sep 7, 2014

glpozza said:
And the unexpected: I guess the lab sold me something else as paracetamol. I mixed to the hidroxide solution and it just sank. Wouldn't mix nor react. .

This happens often with glycin where people are sold glycine instead.
One of my friends is actually adding sodium sulfite for smaller grain. But6 that, of course may change somewhat properties of Rodinal.

glpozza · Sep 7, 2014

Not sure if it was a simple mistake. I've also used the liquid version for a smaller batch and it seems to be easier to mix, since you can add water to the parodinal to reach the final volume, then the hidroxide, cool it, and the sulfite. Downside is that the liquid paracetamol is for kids, and now the lab smells like cherry.

Gerald C Koch · Sep 7, 2014

Sodium hydroxide is dangerous and should not be handled by people who lack experience manipulating dangerous chemicals. It can cause severe burns. When added to water it causes an exothermic reaction which can cause the mixture to explode due to the large amount of heat released.

I find it rather odd that you can obtain sodium hydroxide and sodium sulfite but cannot obtain any commercial developers other than D-76. If you can obtain some Metol you would be better off making D-23, a good all around developer.

glpozza · Sep 7, 2014

There is a broad use for sodium hydroxide, while the number of b&w photographers in Brazil interested in other developers isn't really on the rise. I'm using all the protections for the hydroxide, to the point of having a little OCD in the lab.

Gerald C Koch · Sep 7, 2014

So it's not a matter of certain developers being considered dangerous. Certain countries have restrictions on Rodinal-like developers considering them to be caustic and hence dangerous.

If you can get D-72 (Dektol) it can be diluted 1+9 and used as a film developer. Average developing time is 10 min @20C.

ME Super · Sep 7, 2014

Gerald C Koch said:
Sodium hydroxide is dangerous and should not be handled by people who lack experience manipulating dangerous chemicals. It can cause severe burns. When added to water it causes an exothermic reaction which can cause the mixture to explode due to the large amount of heat released.

While what you say is true, with proper care, Sodium hydroxide can be handled safely. It's used as a drain cleaner here in the US, after all.

The same can be said for compound X, which has the following properties:

Extended exposure to the solid form of this compound can cause tissue death.
Exposure to vapors created by boiling this compound can cause severe burns.
Inhaling the liquid form of this compound can be fatal.
It makes automobile brakes less effective.
Solid and liquid forms of this compound can cause car tires to lose traction.
This compound is 66% hydrogen, a known explosive.
This compound causes things to rust.

Compound X is water, yet everyone knows how to handle it safely. Armed with the proper knowledge, lots of dangerous chemicals can be handled in a safe manner. We handled sodium hydroxide in a safe manner when we were high school students. The same goes for Hydrochloric acid. Mix 500 mL of a 1M solution of sodium hydroxide with 500 mL of a 1M solution of hydrochloric acid, and you end up with 1 L of a 1M solution of NaCl - salt water. In high school chemistry class, we made these two solutions and mixed them together to do exactly what I just described. If an unruly bunch of high school students can do this, then glpozza should be able to do this no problem. Just be sure to follow appropriate safety protocols.

Gerald C Koch · Sep 7, 2014

ME Super said:
While what you say is true, with proper care, Sodium hydroxide can be handled safely. It's used as a drain cleaner here in the US, after all.

Sodium hydroxide can be handled safely if one follows directions carefully. Sadly most people don't bother to read the very detailed and explicit label or an MSDS . A few years ago a woman sued the manufacturer of a particular brand of lye even though she did not follow the directions. She used more than was recommended and used hot water. She lost the sight of one eye. The court held in her favor against the company.

One of the worst threats to safety is over-confidence. In the case of strong acids and bases a face shield would be a better choice than safety goggles.

ME Super · Sep 7, 2014

This is how we end up with products that don't work - people don't read or don't follow the directions on the ones that do work, so they change the formulas to make them safer - then they don't work as well.

A few paRodinal questions.

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