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.
http://www.rogerbeck.com/LFPF/Garden%20of%20the%20Gods%2012fb.JPG
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.
http://www.rogerbeck.com/LFPF/tanks.jpg
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/product/65329-REG/Arkay_602345_81_14HR_Stainless_Steel_Hanger.html
http://www.rogerbeck.com/LFPF/racks.jpg
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.
http://www.rogerbeck.com/LFPF/arkay7.jpg
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.
http://www.rogerbeck.com/LFPF/Garden%20of%20the%20Gods%2012fb.JPG
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.
http://www.rogerbeck.com/LFPF/tanks.jpg
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/product/65329-REG/Arkay_602345_81_14HR_Stainless_Steel_Hanger.html
http://www.rogerbeck.com/LFPF/racks.jpg
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.
http://www.rogerbeck.com/LFPF/arkay7.jpg