Chemistry

[Ed Sukach]

In using both C-41 and RA-4 chemistry, there is a definite shelf life, which can be extended - a lot - by displacing the oxygen in partially filed containers with an inert gas.

JOBO / Tetenal catalogs a product called "Protectran" for this purpose. In trying to get this (comes in a spray can - I have *one* left), I was just informed that it has been discontinued, and I am searching for a suitable sustitute.

I know that most of the chemistry manufacturers recommend dry nitrogen. The problem here is a source of dry nitrogen. So far, the only one I've found would be
a supplier of industrial gasses - an entire "tank" for $LOTS.

Somewhere, I've read that the suppliers of fine wines carry spray cans of argon, for displacing the oxygen in partially filled wine bottles.

Anyone here have any knowledge of argon - which I undersatnd is an inert gas - and its probable effects when used to preserve photographic chemistry?
Or another suitable replacement for "Protectran" or dry nitrogen?

 

[Donald Miller]

Ed,
If you have a window manufacturer near you they will probably use argon and possibly other inert gases as a UV shield gas for use in "Low E" windows. I would think that any of the gases in the argon, xenon, nitrogen, possibly even helium class would work as a shield to slow oxidation of the chemicals.

As an aside, I have heard other photographers that use marbles in their partially filled chemical bottles to displace the liquid enough to limit the inclusion of oxygen through partially filled bottles. I have seen marbles that are used in some of the crafts in craft stores. Not sure if they are glass, though.

Good luck, let us know what you come up with.

 

[DKT]

well, the good news is that a tank of nitrogen should last you a lifetime....fwiw, we use "hospital grade" nitrogen with our Wing Lynch machine for doing E6. Nitrogen comes in different grades, and some of it can have small amount of oxygen mixed in as well.... I messed up once & ordered a lower grade of nitrogen and the chemistry really suffered--live & learn. I would think (don't know though) that you could get a smaller tank-size? I've seen photos of a portable WL machine once--that was the top part of model 4E fitted into a truck. If I remember correctly, the picture I saw had a small nitrogen tank lying alongside it. About the size of a scuba tank. Kreonite and some other manufacturers make nitrogen generators for the lab industry though, but I know they cost $$$$ compared to just getting the tanks...once you pay the deposit, the price of the gas really isn't that much. If you actually use it up, the next tank is alot cheaper...we use about 2-3 a year, but I think for what you're doing a tank would last forever almost. can't help you on the argon though, every lab I've ever been in has just used nitrogen.

KT

 

[clogz]

Surprised to hear that Tetenal has discontinued Protectan. Used to be good stuff.
In olden days photographers used socalled photo ether to keep their chemicals.As such this is no longer produced by the photo industry but...could'nt we just use normal ether?

Does anybody know?

 

[b.e.wilson]

The difluoroethane in products like "Dust Off", typically used to move dust off film and into the air, is unreactive and will displace air quite nicely. You can even invert the can and spray some liquid into a bottle and cap it as it evaporates to displace even more oxygen (just pointing the nozzle into the top of the bottle and shooting gas in always brings more air with it). Just be sure not to cap it before the bulk of the liquid has evaporated and displaced the oxygen, and never do it with a glass or other rigid bottle.

 

[Ed Sukach]

I contacted JOBO tech for information on a "Protectan" subtitiute - got a "You're on the List" answer ... so I'm waiting.

While I was there, I mused about and came up with this information from their "Support" section ... "JOBO Quarterly - Issue #4 - JQ9404." This was written by Paul Rowe, a much missed member of the JOBO organiztion who passed away a few months ago.

The article was titled: "Color Negatives - The C41 Process".
Paul had conducted quite a bit of research into the process, with specific consideration to uniformity and consistency of processing - these were his conclusions:

1) Pre-wet of the film produces unpredictable variations.

2) Acid stop bath introduces unpredictable variations.

3) Rinse (using water instead of stop bath) after the developer introduces unpredictable variations.


All of which seems to agree with my own experience, although I haven't been anywhere near as thorough as Mr. Rowe was.

The *ONLY* place I use stop bath now is in RA-4 Color Printing... I believe it *IS* necessary there.

I know it is risky to try to extrapolate this to Black and White processing - but I think there may very well be valid parallels there.

Comments?

 

[Aggie]

..

 

[glbeas]

I've never presoaked a piece of film in my life. Never had a problem with it. What happens with you Aggie?

 

[Aggie]

..

 

[glbeas]

I think that would happen with me if I got the developer into the tank too slowly. Does this happen with all film developer combos? All tanks? Then maybe the stuff I shoot just never shows that kind of defect off. It *is* kind of odd how that happens.

 

[Aggie]

..

 

[glbeas]

Well how about the kind of developer? I mostly use Rodinal, pretty dilute stuff. You use a pyro developer? Might be if I used your developer I'd start having that problem too and have to adapt. There has to be some real reason for it.
Makes me real curious.
Lately I've started using dip n dunk for my C41, I was getting a bit leery of the fill times for the tall tank as compared to the 3:15 developing time. Didn't leave much leeway. Besides that the damn lid always leaked and I hated how the bleach would dribble everywhere while I inverted the tank. Dropping the reels into prefilled tanks is so much cleaner!

 

[Aggie]

..

 

[fhovie]

""The difluoroethane in products like "Dust Off", typically used to move dust off film and into the air, is unreactive and will displace air quite nicely.""

I had thought of doing this but hydroflorocarbons never seemed like they qualified as inert. I would try it by I am not a chemist and am concerned about reactions in chemistry I don't completely understand: C41 for example. None of my B&W chems really need this - I do use marbles - dark glass and mix only what will be used in a short time.


As far as presoaking goes - I can't imagine not presoaking 4x5. I think 35mm would probably not care. My first 4x5 tank was square. I wasted a whole box of film learning that square daylight tanks are the wrong answer - I always got uneven development. Even with the Jobo tank, I always presoak off the anti halation layer. I read (Adams) that it takes 20 seconds for the chems to permeate the emulsion. It makes sense to let the chems displace the water evenly as opposed to permeating the emusion at different rates in different spots. I also don't want that unknown chemical disolved layer in my developer. Of course C41 was designed to run that way.

 

[Ed Sukach]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (glbeas @ Apr 12 2003, 07:16 PM)</td></tr><tr><td id='QUOTE'>
I was getting a bit leery of the fill times for the tall tank as compared to the 3:15 developing time. Didn't leave much leeway. </td></tr></table><span class='postcolor'>
I guess I'll have to take my place with the "odd" crowd again.

I've made my share of mistakes when it comes to processing ... wrong temperature, wrong time ... needless to say, a *host* of others. I've come to view these "excursions" as "interesting experiments" in alternative processing rather than "disasters."

I would submit - prepare for sacrilege - that color processing .. both C-41 and RA-4 is nowhere near as sensitive as the film producers would have us believe. My theory is that, if the results out of the darkroom are not up to the expectations of the "small operator" - imagined or real - the manufacturers can always fall back to, "Well, you didn't maintain a developer tolerance of +/- 1/4 degree F!!" Saves them a lot of time in technical service calls.

JOBO did a *lot* of investigation into the "uneven development" idea - the operation of filling their tanks allows the developer to reach the outer film on the reel before that on the inner - and after knocking themselves out trying different film/developer/fill times with *many* densitometer readings, concluded that, for all intents and purposes - even among the "pickiest" - there wasn't diddly-dit of difference. I think the greatest variation was something on the order of 0.01, which could be caused by a LOT of other factors.

I remember reading - both from Ilford and Agfa - that pre-wetting was to be avoided - something to do with water "swelling" the emulsion and causing image degradation - without adding anything to "even-ness". For a time, the idea of adding a wetting agent - dilute Photo-Flo, or my choice for wetting, the Edwal stuff - to the developer was in vogue - but that sort of "faded".

I have been wondering about the "No less than a five minute devloping time" proscription for some time now. I've done a *bunch* of 3 minute and 15 seconds C-41 processing over the years with *no* "uneven development" problem that I could see.

As a matter of fact, Irving Penn in his book "Worlds in a Small Room" states that most of his photography was done on "Tri-X , exposed at 160 ASA, or 80 to 125 for very dark skins. Development was usually in (Ethol) UFG , 3 to 5 minutes at 68F." Note the "three".

Considering Penn's work in this book, I'd have no problem doing the same. If my work could only be half as good...

 

[Ed Sukach]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ed Sukach @ Apr 11 2003, 12:27 PM)</td></tr><tr><td id='QUOTE'>I contacted JOBO tech for information on a "Protectan" subtitiute - got a "You're on the List" answer ... so I'm waiting.
</td></tr></table><span class='postcolor'>
JOBO did reply ... I received this back on Sunday, the 13th ... Someone dedicated enough to reply on a Sunday?!!!


Subject: Protectan Spray
Date: Sun, 13 Apr 2003 12:38 EST

From: Mark Williams <mark@jobo-usa.com>
To: `Ed Sukach' <SukachEd@netscape.net>

Dear Ed,

Tetenal decided to stop shipping this to us, despite the fact that it sold well. I don't know why. The can was a mixture of propane and butane. I know of people who have stared using a plumber's torch (propane) to fill the bottles, and some who have used canned air from the enlarger area.

We have never tried or used argon gas, so I don't have any comment on that. You can check it out with the various online chat rooms dealing with photography and see if any one has used argon gas. For my money, the plumber's torch works fine. However, the company does not officially endoese this method (IE-some knucklehead will blow up their basement-even though Protectan is just as flammable).

Thank you,
Mark Williams
Customer Service
(734) 677-6989 X9440
Check out PermaJet papres at www.PermaJetusa.com


I appreciate this a great deal, not only for the "Sunday" response, but for the fact that Mr. Williams had the ba -- uh ... testicu .... uh ... *SISU* to honestly say "I don't know", instead of piling on a bunch of beef by product.

I'm going to continue the search. I see, from the "Wine" sites that there are also "vacuum" devices used to withdraw air from opened bottles...

It could be that Tetenal was afraid of the "explosive knucklehead" and that was their reason for discontinuing Protectan.

 

[Tom Duffy]

"The can was a mixture of propane and butane. "

Holy shit! I always thought it was some inert gas. and I always made sure I used plenty of Protectan in my closed darkroom to make sure the chemicals didn't oxidize! When I get home I'm going to read the label on the can. and to think I was more concerned about using pyro...

It's been my experience that even working strength RA-4 tetenal lasts 2 months in a bottle without a problem.

 

[b.e.wilson]

Propane and butane are inert...to most reactions but combustion.

Add fluorines instead of hydrogens, as in the case of difluoroethane in "Dust Off", and the gas remains unreactive and is less combustable. Add lots of fluorines and chlorines, and it becomes completely inert and damages the ozone layer.

There is a problem with using any of these gaseous products: once you've displaced the air in the headspace of your container and seal it, the new gas, because you have not bubbled it through the solution, will begin to dissolve into the liquid and create a negative pressure in the bottle, possibly inspiring air. Any gas will do this if it is added in the gaseous form. Gasses in the (temporary) liquid state will too, but when they evaporate they create enough of a positive pressure that when some gas dissolves there is still a positive pressure in the container to keep additional oxygen out.

But speaking kinetically, refridgeration is more effective for preserving oxygen-sensitive solutions than replacing air with inert gasses, at least over periods of a week or two. That is, if the solution's solubility isn't harmed by cooling.

 

[DKT]

hmm, interesting. well, I can tell you that on a Wing Lynch machine, the nitrogen does two things. Primarily the pressure in the tanks works to pump the solutions out and into the processing trough located above. The tanks are sealed up, and a nitrogen blanket is laid down on top of the remaining chemsitry this way. It's really a simple processor in a way, and very trouble-free, because there's no pumps to worry about it--the only moving part is a drive bar--that rotates the tube sets you load your film onto. At any rate, even with a setup like this, using the best nitrogen grade, you get about 2-3 weeks tops for E6 chemistry. One thing they'll recommend, even while using the nitrogen blanket as a selling point--is to "top off" the chemistry weekly with fresh mix. So you pretty much try to turn it over ASAP. My experience has been that after a week, you can start to see things like the color dev starting to darken a bit, and maybe the first dev. turning slightly as well--the sorts of visual indicators of oxidation...we usually try to use it every day, and top it off at least once a week. btw--the way they recommend topping off, is to purge the nitrogen actually as you reseal the tanks--they have these rubber gaskets for a seal. You pump out a bit of chemistry and screw the cap on & seal it up. When the seal is made, the chem runs down the drain...the nitrogen runs into another part of the tank though, along with the heaters & temp probes etc. The whole beast sits there at processing temp round the clock, ready to go.....

KT

 

[MichaelBriggs]

The MSDS available from Jobo USA website has always disclosed the composition of Protectan as propane/butane.

The approach is to displace the oxygen in air with some inert gas. Propane and related compounds have the advantage of liquifying at room temperature under pressure -- this allows a larger quantity to fit within the can. The obvious disadvantage is the inflammable nature. Nitrogen, argon or other noble gasses should work well. You don't need a super high purity grade -- as long as you greatly reduce the amount of oxygen in the bottle, the lifetime of oxygen-sensitive photochemicals will be extended. Argon probably wasn't selected for the photo trade because of its expense. Propane/butane doesn't sound nice for wine and might impart a flavor, hence the selection of argon.

Another consideration is the container. Many plastics, even those used for some bottles intended for photochemicals, are permeable to oxygen. I have had the best results keeping B+W developers using glass bottles. The disadvantage of glass is the weight, breakability and possibility of injury from broken glass. Another approach is to limit the amount of oxygen by using full bottles -- either use smaller bottles, or add marbles. The smaller bottles will work if the material is impermeable to oxygen -- if the material is permeable to oxygen, the higher surface area to volume ratio of a small bottle will increase the oxygen reaching the photochemicals.

 

[inthedark]

I like the idea of marbles mentioned in the earliest posts of this thread. But when I buy industrial sized stuff which I have to do, they used to come in collapsable bladders. So when they went to rigid plastic last year (they being Agfa) for there 5 gallon stuff, I went to a camping store and bought collapsable water bladders, they work great at keeping the air out of both stock and tank solutions when not in use. In a pinch once when I only made up a very small portion of chemistry for some testing, I used vinyl gloves filled with the about 500ml of solutions and rubber banded the wrists. This worked for over night but not for a long haul. Hi, btw, I'm new my name is Jill. Should have put that as my ID but I wasn't thinking I guess. Not too internet savvy, sorry.

 

[Aggie]

..

 

[Robert]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ed Sukach @ Apr 14 2003, 08:14 AM)</td></tr><tr><td id='QUOTE'> </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ed Sukach @ Apr 11 2003, 12:27 PM)</td></tr><tr><td id='QUOTE'>I contacted JOBO tech for information on a &quot;Protectan&quot; subtitiute - got a &quot;You're on the List&quot; answer ... so I'm waiting.
</td></tr></table><span class='postcolor'>


Tetenal decided to stop shipping this to us, despite the fact that it sold well. I don't know why. </td></tr></table><span class='postcolor'>
Notice he said they stopped shipping it to them. Now to me that means it might still be available. It might mean a trip to Europe or at least a European website. With the shipping restrictions now in place wouldn't suprise me if alot of stuff stops being sold.

I know you said a nitrogen tank costs alot but was that just the gas or was that including the tank cost? If it includes the tank then that's a one time cost and you need to check the refill cost. I've got a CO2 tank for draft and the tank cost me something like $100 years ago. The refill is maybe $20 and it's a big tank that goes years between fills. Some bars use nitrogen for pumping wine [or they did] and others use a nitrogen tank for Guiness. I'm guessing beverage grade would be good enough?

I'm suprised he mentioned the torch idea. You know some genius is going to check his fill level with a match.

It's still on this website:

http://www.silverprint.co.uk/chem9.html

 

[DKT]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Robert @ May 4 2003, 02:41 AM)</td></tr><tr><td id='QUOTE'>. I'm guessing beverage grade would be good enough?

</td></tr></table><span class='postcolor'>
No, it would be best to use the purest grade, some call it "hospital grade". we use a grade 5.0--"oxygen free". I screwed up once & ordered a lower machine type grade & pretty much killed our E6 chemistry, or at least diminished it's life quite a bit....I'd check with an industrial gas supplier in your area--the tanks aren't that much money really, once you do the deposit. It's not like you'd need a fancy regulator either for what you're doing....

KT

 

[Robert]

Off the top of my head a person would need

1) Tank
2) regulator
3) A beverage tap. A cheap one aimed at dispensing wine should be fine.
4) A length of hose and some clamps.

I think that's it.

Beverage grade is pretty pure. Oxygen will cause problems for beer and wine the same way it would for photographic chemicals. I think the problems with lower grades are things other then Oxygen. Wouldn't oxygen be less of a problem with medical grade nitrogen? I can't find anything describing beverage grade nitrogen. Well nothing more then calling it pure. I did find medical grade and it does include a very small amount of oxygen. 8ppm