Just got done reading the article on nitrogen burst agitation in View Camera.
Question out of mere curiosity: why nitrogen? Why not air from a scuba tank? Is it because nitrogen is inert? Isn't air inert enough? Are development times so long that aeration of the developer is an issue?
Nitorgen is used to minimize the oxidation.
steve simmons
Although I have not yet read the article in View Camera on nitrogen burst agitation I have discussed and exchanged many messages with Michael on the subject. There is no question in my mind but that nitrogen burst agitation is an ideal system for minimal type agitaiton procedures, which is capable of giving more apparent sharpness with enhanced adjacency effects, along with highlight compensation.
If nitrrogen burst type systems can be produced and sold at a reasonable price I have no doubt but the system will become very popular.
Hopefully View Camera will follow up on Michael's article with details of future testing, etc. For many of us this method of agitation would appear to be ideal and I really look forward to more information.
Sandy King
Steve hit the nail on the head in the fact that Nitrogen is inert and as a result, it avoids unintentional chemical interaction with developers. Secondly, once one acquires a tank (that will always hold its value), the nitrogen is very inexpensive. I am taking in my empty 16 ft3 test tank next week and upgrading to a 65 ft3 one and the difference in the price of the larger volume of nitrogen is only a few dollars more than the smaller volume.
I found the film developing system so easy and "hands off" I decided to put a coffee pot in the darkroom.
Cheers!
A hard rubber or stainless tank set for film or paper, along with saran baskets for holding the film or paper is one of the most reliable ways of processing large sheets. Even better are stainless hangers.
A nitrogen sparger goes in the bottom of the tank, and a timer/pressure regulator goes above the tanks.
The sparger moves along with the rack which holds the film or paper, so you only need one of them.
This system was used by Kodak when color processing was released to the public in the 50s. It has been used ever since. I loved using it. We had this installed in every lab at Eastman Kodak where we processed film.
In cylindrical film tanks, which we often used, we had sets of spiral spargers fitted to each type of cylinder.
Ron Mowrey
As I understand from the article, the agitation is not due to the movement of the bubbles themselves but a quick rise and drop in the volume of liquid in the tank attributable to the burst release of the nitrogen gas. If my understanding is correct, this can be replicated by mechanical means other than use of a gas, thus eliminating the need for a gas pressure regulator etc.
The mechanical version is to use hangers and lift and lower the hangers into the tank and developer.
Or, you could do a false floor this is lifted and lowered thereby raisng and lowering the developer. I don't know if designing and constructing this would be any easir.
steve simmons
I have a nitrogen burst system built into my sink which is actually a color processor. I guess it's time to try it out. The only drawback is that it has 2 gallon tanks...EC
Yes, as Steve said, you can dip and dunk sheet film hangers in your tanks to accomplish your agitation.Originally Posted by cyrus
I can say without hesitation that to make the broad comparison that the rise in the fluid level attributed to a gaseous burst agitation with inert nitrogen gas can be accomplished by mechanical means other than dip and dunk is probably a stretch. I would only comment that the darkroom research that Kodak performed to perfect the gaseous burst process was extensive and 100% dependent upon the explicit variables listed in the referenced publication. To deviate from this set of operating criteria is simply foolish because the process works marvelously and since there is no manual contribution in the process beyond putting in and taking out the cage holding the sheet film hangers, it is absolutely consistent. If the costs have you in a pickle, I can only tell you to hunt up these components in the used market because their are bargains everywhere.
In the used market I purchased a gas regulator valve for $15, a tank with plenum for $40 and a solenoid valve and interval timer combination for $50. For another $200 for the large nitrogen tank you are in business for as long as you want to process film. These components are in the basement of used photo stores all over the country collecting dust. That said, one must satisfy their own personal objectives for processing sheet film. My point in writing the article was to at least provide a basic understanding of a proven film processing alternative that has been around for 40 + years and let the reader take it from there.
I can tell you that I have tried just about every processing technique out there in the last ten years and I find that once it is set up, gaseous burst agititation is remarkably easy to use and provides consistent results and negative scratching that is such a risk/possibility with tray processing is minimized to as near zero as possible.
Just another tool to consider adding to your tool box.
Cheers!
Or you could drop a weight in the tank!
I was just curious. Not being familiar with this process (and still not quite sure if its a bit too much for the couple of negs/week that I develop - but then again I'm an ignorant newbie) I had always assumed the movement of the bubbles is what cause the agitation...
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