Preventing Developer Oxidationgreenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread
I recently read about a product offered by Tetenal (only in Europe) that's used to preserve developer in partly filled containers - the product is an aerosol spray that prevents oxidation by creating a heavier than air layer of inert gas on top of the developer.
I was browsing through a Lee Valley Tools catalogue (a Canadian hardware and tool manufacturer and distributor) and came across what's called "Finish Preserve", which they advertise as preventing oxidation & drying of partly filled containers of varnish, lacquer, etc. Sounds like the same thing that is (inronically) made in the USA.
If you're interested, have a look for item 53Z21.01 at www.leevalley.com Current price is $12.95 CDN (about $8.75 US).
-- Dave Williams (firstname.lastname@example.org), January 02, 2001
Well, I use a more simple but evenly effective solution: I fill my bottle with glass marbles to remove the air from the bottle. When the bottle is empty, I recycle the marbles.
-- Marc Leest (email@example.com), January 02, 2001.
i use wine bottles with rubber corks and a small pump to suck the air out. check wine maker shops or cook wear shops. the pump is about 15 bucks the corks are 3 or 4 dollars a piece.-J
-- josh (firstname.lastname@example.org), January 02, 2001.
The Tetenal product is available in the US via Jobo. You can get it from places like B&H (maybe not until they get their hazmat shipping back available), Adorama, etc. The stuff is a mixture of butane and propane. The can is designed to dispense at a fairly low rate to avoid splashing.
It works. I used it to preserve some Ilfochrome chemistry stored in glass bottles, partially full. According to Ilford the life is 2 months in full bottles. I used it almost 4 months after mixing and it was fine.
Another great way to preserve chemistry is to go to your local welding shop and pick up a small tank of nitrogen with regulator. Purge the bottles with nitrogen. CO2 will also work, but not quite as well.
-- Terry Carraway (TCarraway@compuserve.com), January 03, 2001.
Dave, I have been an analytical chemist for over 12 years and preventing reagents from oxidizing during storage is a common problem in laboratories. Here is some practical advice for you. The goal in preventing oxidation in stored developer is to remove the oxygen that is present in the headspace of the container. This can be done by either removing the headspace (such as the marbles technique mentioned earlier or by using collapsable containers). A more common method is displacing the container's atmosphere with an inert one. Two of the most common gasses that can be used are nitrogen or helium which can be purchased from any local welding supply store. Compressed nitrogen can also be purchased from gourmet wine shops which sell small cylinders of compressed nitrogen to prevent partially filled wine bottles from oxidizing.
If you are in a pinch, you may try using compressed Freon which is commonly used to blow away dust. Check the label to ensure that it does not contain air. Most fluorocarbons are chemically inert and will not react with the developer.
There was one suggestion that recommended compressed carbon dioxide. I would strongly recommend not using CO2. Although it would be effective in displacing the oxygen, the CO2 will dissolve in the developer and form carbonic acid thus lowering the pH of the developer.
I hope you find these suggestions helpful.
-- Michael Riccomini (email@example.com), January 03, 2001.
I don't worry about it. I use liquid developers like HC110 and Rodinal I only mix up what I need at the time. I use this developer 1 shot. Chems don't cost that much. You can find almost any developer made as a liquid. James
-- james (firstname.lastname@example.org), January 03, 2001.
Thanks for the reason behind not using CO2. I thought there was some reason, but nothing came to mind. Now I DO use it for preventing oxidation, but in beer making, where a little extra CO2 is no big deal. :)
I use nitrogen. I guess I have to fill the tank every year or two for about $15.
-- Terry Carraway (TCarraway@compuserve.com), January 04, 2001.
I have availability to Nitrogen. Please tell me [I'm sure I once knew this in college, but I just recently forgot] is nitrogen heavier than air? In other words, can you just introduce it to the bottle and it stay in, or is there some special way to use it when purging the headspace?
-- Alec (email@example.com), January 04, 2001.
Alec, it would help to know a little about how your nitrogen system is set up. For example, if it is one of those small aluminum cylinders used for wine preservation, you should be fine. If it is a large commercial pressure cylinder, you will need a pressure-reducing regulator mounted on the tank. A delivery pressure of about 5 to 10 psi is sufficient.
Assuming you are set up, connect a small diameter flexible hose (~1/4 in. latex or clear vinyl) to the nitrogen supply and place the other end into the bottle of developer approximately 1 to 2 in. above the surface of the liquid. Start a gentle flow into the bottle. If the flow splashes the liquid surface at all then the flow rate is too high. Approximately 5 seconds of purging should be enough to displace 99+% of the oxygen. Stop the flow, remove the hose and cap the bottle. Since the density of nitrogen is approximately the same as air, you will not have to worry about the nitrogen dissipating out of the bottle before you cap it.
-- Michael Riccomini (firstname.lastname@example.org), January 05, 2001.
I use the Tetenal product mentioned. It's called "Protectan", and it works fine. It contains propane and butane gas, and I think you can buy that at your gas station or from a sport store. Maybe cheaper too?
-- Patric (email@example.com), January 08, 2001.
I give another vote to the marbles idea. Don't lose your marbles!
-- pjt (firstname.lastname@example.org), January 10, 2001.