• Welcome to Photrio!
    Registration is fast and free. Join today to unlock search, see fewer ads, and access all forum features.
    Click here to sign up

Contamination Basics

Commercial products come in a dispenser can; butane lighter fuel (not "inert" as such, but inert to photo chemicals) comes in a can like an aerosol without the misting button on the valve (I've installed one of the supplied fill adapters that fits my lighter and use that to get a grip to release the gas into a bottle without frostbitten fingers). There are dispensers for carbon dioxide from various sizes of "soda bulb" containers -- 7 g , 12 g, and 14 g are common -- and some of them include a valve (mainly those used as an on-the-road repair inflator for bicycle tires). If you want to spend some money you can get carbon dioxide in a pressure bottle (as compressed liquid, enough to kill your whole family if it leaks in the night) like the ones used for welding, or use a CO2 fire extinguisher (the valves on those aren't great, however; they may leak after being opened the first time).

The most cost effective is butane sold for lighters at smoke shops -- get the cheapest per ounce, it's all the same to us (cigar and pipe smokers may disagree, but we aren't inhaling the combustion products). Yes, it's flammable, but you shouldn't be smoking in your darkroom anyway (good way to ingest chemicals without knowing it, not to mention ashes are bad for negatives), and once it's in a sealed bottle, it's protected from ignition sources. It's heavier than air, so you don't need to back-fill the bottle, you just need enough to make a blanket layer over the liquid surface.
 
ced said:
Avoid contamination like the plague. It could cause unseen failures & you might never know where it all went down the chute. Like any other thing one does with passion do it like advised.
Click to expand...
Under whose/what advise???

Isn't that what the OP is getting here?
 
Sounds like a good practice to me.
 
toejam said:
What tools do you need to put the invert glass in the bottle?
Click to expand...

It is an inert gas - a gas that does not form chemical reactions with other chemical substances. It has to be heavier than air so it sits on top of your chemical and blocks the oxygen in the bottle from reacting with your chemical. The stuff in the wine store comes in an aerosol can so you just inject it into the bottleneck and cap it off. Some people use butane but I don't because it is flammable.
 
If you have a good regime of washing all your mixing beakers etc and drying them, then I think you could use the same items for B&W and C41 or E6.
Chemical storage is a different matter. Each process should have its own set of storage bottles, correctly labeled with chemical name and date of mix.

Back in the late 1970s I worked in a wholesale commercial lab. They used C41, EP2, Agfa CNS and B&W. Each process had its own mixing area, mixing tub etc and they were all colour marked according to their process. I can still remember C41 was yellow, EP2 was blue, Agfa CNS was red and B&W was black. The point being that there would never be cross-contamination as all equipment was kept in its coloured mixing area.
 
Does the butane natural release when I open the bottle? I’ve only seen videos of people making butane water bottle rockets so I’m only imagining a good amount of force in the bottle.
 
The butane you put in with the bottle cap open will equalize pressure before you close the cap. Those videos are squirting liquid butane into the bottle, then inverting the bottle quickly before it can boil off, so the pressure it creates forces the water/soda out and makes the "water rocket" fly.

If you hold the butane can with the valve at the bottom, you'll get liquid, but a short squirt is all that's needed -- and if you don't invert the bottle you're blanketing, and wait for the (visible, if the bottle is clear enough) puddle of liquid butane to boil off, you won't trap excess pressure in the chemical storage bottle. You don't actually need liquid at all -- but it's harder to get butane in containers that expel gas in a position that lets you blanket a chemical bottle.
 
You get a lot more gas in the same size can with butane -- argon doesn't compress to a liquid at room temperature (boiling point well below that of nitrogen). Even if you compress it to 150 atm as would be done with most welding gases, you get a lot lower density than butane at a mere 4+ atm.
 
Donald Qualls said:
You get a lot more gas in the same size can with butane
Click to expand...
Yep. A lot harder to start fires with it too.
Argon smells better than the butane used for lighters.
 
MattKing said:
Argon smells better than the butane used for lighters.
Click to expand...

Matter of opinion.

Yes, butane is flammable and argon is not. That's a factor to consider. The non-flammable alternatives to butane (chlorofluorocarbons) are generally banned for sale to the public, and perfluorobutane (nearly same boiling point as butane) isn't widely available.
 
MattKing said:
Lee Valley Finish Preserve (argon):
https://www.leevalley.com/en-ca/shop/tools/supplies/finishing/30268-finish-preserve?item=53Z2101
Expensive. But kind of neat.
It is rather disconcerting how light the can is!
Click to expand...

I have used this with paints and stains and it does a good job in preserving them. It is safe and easy to use and will do up to at least 75 2 second bursts for gallon paint cans so it extends past that for liter bottles. And yes it is really light - it is like you just bought an empty can.
 
You must log in or register to reply here.
Menu
Log in
Register