Compressed Air to protect developers?

[tonghang_zhou]

I use compressed air to clean negatives for scannning, and I sometimes

wonder whether it's also good to protect developers in half filled

bottles, since it's apparently a pretty safe gas and very convenient.

But I don't know about this tetrafluoroethane that it contains and if

it reacts with various developer ingredients. Would those who know

comment on this? I haven't done any experiement myself. I figure it

would take many months and may not be very conclusive as far as I'd be

able to tell.

[frank.schifano]

The idea is to keep air out of the bottle. Air contains oxygen and oxygen is what you DON NOT want in the bottle with your developer. You DO want to displace the air from the partially full bottle with an inert gas. Some people like to use nitrogen, and others, like myself, find it easier to get a propane tank from the hardware store for this.

[tom_menegatos]

This is from the MSDS for Dust Off

 

"VAPOR REDUCES OXYGEN AVAILABLE FOR BREATHING AND IS HEAVIER

THAN AIR. "

 

It seems to also be non flamable. Probably similar to the Protectan spray that you can't get in the US anymore except that was a propane/butane mix which probably wasn't very safe. Maybe not as effective as Protectan but you probably shouldn't have to worry about fireballs either.

 

I read in a thread about people using argon or something similar that they use in wine making but the argon actually makes the developer go bad.

 

All you need to do is displace the oxygen in the bottle. You can use those accordian type bottles to do that.

[jordan_w.]

Tonghang, the stuff commonly referred to as "canned air" (Dust-Off, etc.) doesn't actually contain air. Compressed air and "canned air" are two totally different things. "Canned air" is usually tetrafluoroethane, as you mention, and I've used it in the past to displace the oxygen from photographic chemical bottles. I had no problems with it. Tetrafluoroethane is pretty inert and there should be no reaction between it and any developer constituents.

 

Keep in mind that there is always dissolved oxygen in water-based solutions (that's where sea creatures get their O2) and that this oxygen could possibly contribute to developer spoilage, no matter how well you remove the air above the solution. Eventually it will all outgas and cease to be a problem.

 

With regard to argon -- I can't see any possible way that argon could cause the decomposition of photographic chemicals. Argon is completely and absolutely inert to everything. Perhaps some contaminant in the argon delivery system caused the decomposition described.

[conrad_hoffman]

Argon bottles are typically evacuated before being filled, so contaminants should be minimal. The stuff is completely inert. It should preserve developers just fine.

[danny_spence]

I've been using canned air in this way for a few years now. In that time I haven't seen any problems with using it to displace air in film and paper developers.

 

The biggest hurdle to keeping developers is the type of bottle used to store them - some plastics are air permeable (like HDPE) and don't lend themselves well to storing developers for an extended amount of time as they "breathe". I believe that the best kind of plastics for storing developers are made of PET or PETE (soda "Coca-Cola" bottles) as they do not let air pass through them. Amber glass bottles are also a good choice.

[jorge_oliveira2]

I use two type of plastic bottles to store my solutions: brown and blue (brown purchased at the photo store; blue at the chemist)

 

The brown ones do not collapse very much when partially filled; the blue ones get very much deformed.

 

My conclusion is that the blues are much less permeable, and I will be changing all bottles to blue.

 

And I do use 'protectan' (gas lighter refuel).

[bob_finley]

I ran a 6 month test on just this question plus I wanted to know if those Pepsi type bottles were as good as glass for storage. I found that butane and dust off worked equally well for preserving developer but the Pepsi bottle with Dust Off collapsed indicating the dust off is absorbed by the liquid. A control bottle with air collapsed the same as the Dust Off but the developer went brown. The developer with no air or half full with dust off or butane all seem to work as well as new developer but I did not do precise comparison on that question. Developer was D-76 stock.

 

BTW the Pepsi type bottles did as well as glass so I now use several to store 1000ml bottles of developer when I mix a new batch of stock. I now have a year old bottle of D-76 (stock, no air) that looks crystal clear but I don't want to open it just yet.

[alec1]

I use nitrogen. Cheap. Totally effective.

[tonghang_zhou]

Alec, what form does nitrogen come in and where can one get it? Thanks.<p>

As to plastic bottles, I find most common bottles are of type "2" as stamped in the recycling symbol (typically on the bottom.) I understand this is not very air tight. Bottles for drinking water are the only ones I can find that are of type "1" (PETE), but they are thin, light and deform easily. They are typically 1/2 liter in capacity. For higher dilution stock developers, I think even smaller capacity would be preferrable.

[normusarms]

Tetenal protectan, Sunsweet prune juice bottles. Drinking prune juice can create an abundent supply of methane, if you could find a way of...nuff said, Norm.

[michael_hohner]

I've seen glass marbles used to fill the bottle (ie. reduce the amount of air in the bottle). Cheap, re-usable, safe, visible, non-reactive.

[scott_walton2]

In the past I have used the marble trick with great success. I would stay away

from the photo containers that look like an accordian because they are really

hard to clean if you use them for another developer... nitrogen works the best

IMHOP and you can get a small can at a gas supply house.

[alec1]

You can find nitrogen at any supplier of industrial gases [check phone book]. They usually have a selection of used tanks, both large and small. You'll also need a simple valve, available at hardware or tool stores, and you're set.

 

It is harmless to both chemicals and to you. I've used it for 20 yrs.

[bob_finley]

Nitrogen is great if you can justify the initial investment in tank and valve (+/- $100.00). Some marbles etch and disintegrate in photochemicals (no personal experience but I have read of others). Butane is great but potentially explosive (tetanol's protectan unavailable in US). Dust Off is cheap, readily available and does the job.

 

As I said before I now mostly decant into smaller soda containers and with the variety of sizes available you can do the amount you want without any air/nitrogen/butane/dust off. Most importantly it is cheap and recycles those wasted bottles.

[gareth_harper]

You want CO2 or N2.

Or better still buy some collaspable bottles.

[jorge_oliveira2]

AFAIK CO2 will not protect a developer.

[jim_appleyard]

Firstly, I try to make up only enough solution to fill my needs. I store the solution in glass. V8 bottles & spaghetti sauce work well. Yes, glass can break, but you know it doesn't breath. I've never had luck with any kijnd of plastic. I then fill up the extra space with glass marbles (do kids play with marbles anymore?). This works quite well. Remember, a solution with eventually go bad, no matter how well stored. Try to use it up before then. You can also try to blow CO2 into the bottle with a straw. It's not the best preservation method, but it's probably better than nothing.

[jordan_w.]

Re: blowing CO2 into the bottle with a straw -- yeah, it'll be better than nothing, but marginally so. Remember that exhaled breath is still something like 15% oxygen (vs. 20% for pure air).

[mike_rosenberg1]

I would not recommend using CO2!! It will dissolve in the ligquid and change the pH - NaHCO3!!

 

 

 

Mike

[kelly_flanigan1]

The 1930's thru 1950's photo books told how to poor parifin in the glass developer bottle' and make a floating lid. We had a 1/2 quart and 1/2 gallon glass bottles like these in the 1970's and 1970's; that worked very well. This surface area of developer exposed to air is radically less; and the their is no special gas required to buy. The clearance of the cooled lid in the bottle determines the fill time; sometimes an extra hole is required for fast filling. I have made about 6 of these bottles.

[graham_line]

Place I worked in West Virginia (1970s) used one of those hard rubber developing tanks with a floating lid. Always took my personal stuff in to soup on Tuesdays because the boss mixed his fresh developer every Monday.