Nitrogen Processing

**Roger Beck** · 14-Nov-2019, 12:25

Nitrogen Burst

I thought I would share how nitrogen burst processing works, it's all in Kodak Publication E-57 "Gaseous-Burst Agitation in Processing" from 1979 and will give evenly processed negatives. The last run I did after making a couple of changes came out perfectly processed. The 8x10 cloud image was tweaked with extreme contrast to bring out imperfections and processing anomalies. The negative was processed with the top of the image at the bottom of the tank, closest to the bubbles. Nothing. Not even edge marks. I'm preaching to the choir and most of what I learned was from this forum and its members, thank you for your generous help.

I was originally going to call it Bubble Agglomeration In Nitrogen Burst Agitation because that is where the process is delicate. The bubbles come out of the plenum 1/4" from bottom in 1/64" holes (Kodak recommends 1/32" or smaller) spaced alternately 1/2" apart at 30 degrees pointing down, in one second bursts every ten seconds at 35 psi, bounce off of the bottom and flow upward forming a closely and evenly spaced group of small bubbles. The rising bubbles don't agitate the developer, they displace it 5/8" inch. The up and down movement give it the regular, intermittent and random agitation needed for uniform development. Problems with bubble streaking occur if they are not evenly spaced or are too big. The system is scalable up and down and I don't see why it couldn't work for 11x14 and larger, the plenum just has to match the size of the tank. If you buy existing parts you can assemble a system with a wrench and screwdriver.

Tank - The original 3+1/2 gal Kodak Hard Rubber Tank at 10+1/4" high would work fine if it were one inch taller to accommodate a plastic tube plenum. A tank that accepts Kodak racks and is tall enough for gas burst has inside dimensions of 7+7/8" wide x 10+7/8" deep x 11+1/4" tall. California Stainless or Arkay may have some old stock but last I checked they were pretty low, they also will make custom tanks and plenums. Raising the height of a Kodak tank 1" around the top will get you started right away.

Racks and Hangers - Kodak Developer Hanging Rack 40 with Hanger Separators for 3+1/2 gallon tank. Usually the rack and distributor are separate items, but Arkay made them as one piece, on the right. I haven't used it but if it works as-is it is a good deal. Normally there would be more tubing at the bottom.

https://www.bhphotovideo.com/c/produ...el_Hanger.html

There is a smaller 2 gal. version of the Arkay rack/tube combo that holds 7 hangers, the metal frame keeps the tubing properly spaced.

**Roger Beck** · 14-Nov-2019, 12:26

Gas Distributor (sparge or plenum) - I bought mine from California Stainless and added holes. I drilled a 1/64" hole every half inch, plus the ones that were there, for a total of about 110 holes, it came with 22. I glued 1/4" rods to the bottom, weighted it down with an iron rod and wired the tubes for even spacing.

Connections - - The compression connection came with the California Stainless plenum and the other type is a nib from an Arkay tank.

Gas Timer - Usually made by California Stainless or Arkay . They can be also be made from Grainger parts. I use the recommended 1 second burst every 10 seconds.

Nitrogen Tank and Gas Regulator - Gas supply stores have compressed nitrogen in several tank sizes. It is pressurized at 2000 psi and a gas regulator brings it down to a usable psi of 20-40. The pressure of the original Kodak setup was 15 psi, mine uses 35 psi to raise 3+1/2 gal. of developer 5/8". Whatever psi makes the liquid rise 5/8" is what works. I use a Smith #30-150-580.

And that's my setup, the rest of the details and specs are in Kodak E57 and will show you how to connect everything with tubes and clamps. I don't have a link for it but I can send you a copy of mine. The key for me was 1) lots of tiny holes for tiny bubbles, 2) plenum positioned 1/4" off of bottom of tank, 3) burst pressure, duration and timing. These settings are a starting point and what has worked for me and not a refutation of anything else. If you are using nitrogen can you post info/pictures and descriptions, especially non standard sizes.

**Peter De Smidt** · 14-Nov-2019, 13:51

Thanks for the write up!

**Tin Can** · 14-Nov-2019, 14:45

Great documentation Roger, thank you!

I run a stock Calumet gas burst system, I made my own timer as the 2 old ones I obtained didn't work

I find it very easy to use and we can turn the lights on between baths

**Michael Kadillak** · 14-Nov-2019, 17:54

Glad that you got things figured out Roger and thanks for sharing. Persistence as they say pays dividends and you were surely persistent.

**Mark Sampson** · 14-Nov-2019, 19:18

It's worth noting that a system like this is best suited to a properly replenished developer and a fairly large amount of film. Once it's dialed in it works very well; I used a nitrogen-burst system from 1985-1991 or so when I worked at Kodak. (The Wing-Lynch 4E which replaced it was a very different beast.)