Tuesday, June 28, 2016

Putting That Chemistry Degree To Work

I have been a user (if not a devoted one) of caffenol ever since I ran into Reinhold's blog and saw the wonderful results he and others like Jon Caradies get with that simple 3-ingredient developer. I do enjoy weighing the ingredients on my little 3-beam balance and making the solution. The smell is a little funky, but I think it's growing on me and I don't mind it so much anymore. I even have my own modest gallery on Flickr where I upload various films both expired and fresh that have been processed with this earth-friendly concoction. Here is the first photo I ever developed and shared that was processed with caffenol-C-L.

Youth Football Trophies

I even went out on a limb and made my own variant, substituting ground up eucalyptus bark. I called it eucalyptol. You may have read about it HERE. That one needs to be revisited with a little different methodology, but I'll save that for another post. For this post, I want to talk about something very different. Okay, maybe it isn't "very" different. It is still a 3-ingredient developer made with things that are readily available at your local drug store and/or online. I chose to get my ingredients online just because it is easier than driving around to different places trying to find things. So what is this "different" developer? It is called Parodinal because it is a Rodinal clone based on Paracetamol. Paracetamol, also known as Acetaminophen, is the active ingredient in Tylenol which is cheap and abundant. Here is the shopping list and the amounts I use for a single 250 mL batch.

  • 30x 500mg Paracetamol tablets
  • 50gr of Sodium Sulfite (Anhydrous)
  • 20gr of Sodium Hydroxide (Anhydrous)
  • Water (distilled) to make 250ml

I based this recipe on what I found over on Martin Zimelka's blog. He in turn learned about it on APUG (I think).

For my first batch, I went simple. I made the Sodium Hydroxide (drain cleaner crystals) solution, then I just crushed up the Tylenol tablets with a stainless steel mortar and pestle and tossed it in. The Sodium Sulfite did not dissolve even in warm water, so I just combined the two as best I could and figured it would either work or it wouldn't and if it didn't, I'd try something different. But guess what? It worked!


It was a cloudy suspension for sure. The binders and coatings of the ground up tablets did not dissolve and just sort of sat there. They didn't seem to have any effect on the action of the developer and that jives with things I read online. It's just sort of disconcerting to have a cloudy developer. You get the feeling that that all of that sediment is somehow ending up on your film. To get around this, some people either start with neat paracetamol. That gets around the sediment problem, but it is a little more expensive and a little more difficult to obtain. Others filter the binders out of the solution, I suppose with something like a coffee filter. That is also effective, but sheesh! That can take a loooong time to filter. Who has the patience for that? So what is a chemist turned data scientist to do? Extract the paracetamol away from the binders! Alright, so that isn't really going to save me any time. In fact, it's probably going to take a lot longer since I don't have a roto-vap handy. Ah well, it would be fun and interesting to see if I could get a clear developer that worked.

So off I went to the hardware store to find an organic solvent that would dissolve the paracetamol and leave the binders behind. I had done some internet research and found out that methanol is great at dissolving paracetamol. But pure methanol is hard to buy because it is quite poisonous. Next best? Ethanol. Denatured alcohol is mostly ethanol with a little bit of methanol thrown in to make it undrinkable. I ground up 36 tablets, just in case the extraction efficiency was low. I ground them up very fine and poured it into a bottle with 200 mL of denatured ethanol. I shook that for a few minutes. Then I let it settle and poured the supernatant (the clear part) through a coffee filter into a plastic tub. Thinking back, a shallow glass dish would have sped things up. That took about 2.5 days to evaporate. Yeah, I know. Filtering would have been faster, but this has more 'cool factor'. Once the ethanol evaporated, I had a pink-ish powder. I scraped it off the walls and bottom of the tub and weighed out 15g. I ended up with a few grams left over, so that means that the extraction efficiency is quite high. Now I used that as my paracetamol source and followed the recipe as before. Bingo! A nice clear solution (with some of the sodium sulfite settled on the bottom). I let it 'age' for a few days and a sort of 'crust' formed on the top. So I gave it a shake and re-filtered this off along with the extra sulfite. The next day, the usual 'rodinal' crystals formed on the bottom of my bottle and I knew I was in business. I had a nice clear parodinal with preservative crystals. The only thing left to do was to develop some film. So that's what I did.


So what are you waiting for. Get out there and make some developer! :)