Is there a chemist in the house?

[Donald Qualls]

Jane, I, too have heard/read about the peroxide formation on stored containers of ether.

Worthy of note is *where* I've read about it: in relation to bottles/cans found on back shelves of high school chemistry or biology labs, for the most part, where a forgotten container has had literally years to sit and oxidize. If the container is well sealed, the formation of peroxide is quite slow, and if you're using the ether rapidly enough to go through a container in less than, say, a year, you're in much more danger from accidental ignition of the vapor than from formation of the peroxide.

If you see a white crust around the stopper, call the bomb squad; do NOT attempt to open, move, or dispose of the container. But if you rotate your supply you'll never see that white crust.

[Dan Jolicoeur]

Calimity; God Bless You!

[Calamity Jane]

Thanks Donald! Some good, to the point information!

I have used ether before (for specialized cleaning, engine starting, etc.) and I am well aware of the immediate hazards. It has its potential hazards but not much worse than some of the other chemicals I have worked with. It is just that I had never heard the warnings about peroxides until I read it in the MSDS data sheets.

The MSDS sheets stated that peroxides begin to form immediately on contact with air but didn't indicate the rate of peroxide accumulation or the amount of peroxide that constitutes an explosion hazard. The data sheets also talk about how to neutralize the peroxides.

My local supplier carried ethel ether in 1L bottles, so that's almost 10 batches of collodion (by both Coffer and Osterman) so I am not sure I would get thru a full bottle of ether in one year.

Definately ether will be stored out of doors in my "dangerous goods" cabinet out in the yard!

Thanks for the information guys!

[Harold_4074]

CJ--

There is a wealth of information on the Web about the chemistry and hazards of peroxide-forming chemicals, of which ethyl ether is one of the more problematic. Storage in a refrigerator is not the answer: there is apparently a temperature regime in which the peroxide reaches the saturation limit and crystallizes out, thereby disturbing the natural equilibrium between formation and decomposition. There is also an issue of minor vapor escape from the container building up a dangerous concentration inside the refrigerator, which then takes on some of the characteristics of a bomb.

I recommend the Americal Chemical Society monographs on ether hazards; many of the web sites are alarmist rehashes with little technical content. Why do I know this? Because a while ago I was helping to clear out a basement and came across a gallon jug, three quarters full, labeled in wax crayon "Waste Ether" (the jug itself still had the Merck anhydrous ether label on it). It had apparently been acquired (twenty years ago) by a gunsmith, for degreasing parts; he got it from a dental school....I suspect that the wax content from the dental work was what kept us all from being incinerated. I set the jug down---very, very, gently---and did some serious Web research before advising the owner to let the fire department deal with it ( the house was subsequently sold, intact, so I guess it all worked out).

In the case of collodion, I believe that the solvent is actually a mixture of alcohol and ether (for reasons which I think I understand but don't feel competent to explain). This is probably much less hazardous (but only with regard to peroxidization) than pure ether, so one strategy might be to stock only the mixture, without storing pure ether. (This is where you really need a chemist...)

Whatever you do, please don't abandon a gallon jug of it under the bench....

Good luck!

[Mike Gudzinowicz]

You can acquire ethyl ether stabilized with ethanol which slows peroxide
formation, or you could add 3 to 5 % ethanol to the ether (v/v). Merck sells
test strips (Merckoquant ether peroxide test strips) for peroxides. Ether
with a level of over 50 mg/l should be treated to remove the peroxides. Consult
any standard text on organic chemical purification techniques for methods, however,
the ether should be used immediately after treatment. Generally it is better
practice to buy small quantities of stabilized ether, dispose of the unused
portions of opened containers after a few months, and wash the can or bottle
repeatedly before disposal. You really don't need "pure" ether for your purpose.

Do not store ANY flammable solvents, especially ether, in a home refrigerator.
Explosion proof refrigerators are available for around $2K for a small unit. Home
models are not vented, and any spark from a switch, bulb or motor may cause
an explosion.

[fred arnold]

Let's not forget that ether fumes will also form peroxides with exposed metal in your storage cabinets/refrigerators. When I did wet synthesis we considered any can more than a few weeks old to be suspicious. Probably overly cautious, but we had other interesting chemicals around that could react with an open ether can. It also meant that if the grad student couldn't personally remember opening the can, we weren't going to trust it. Luckily most of our chemistry ran in THF or Chlorobenzene.


You can dry ether over aluminum oxide or sodium/lead alloy to prevent peroxide formation. Otherwise, never let your ether still boil down, as you'll concentrate any peroxides present as the ether boils off. I presume this warning applies to cans of it as well, so that natural evaporation will concentrate any peroxides formed. They also react poorly with strong oxidizers, so be careful with the permanganate, dichromate, and silver nitrate near the ether.


University of Alberta has a recommendation for a home-made test, but I prefer Northwestern's approach; commercial test strips, monthly checks, signed dates for those checks attached to the can, and disposed of no later than 6 months after opening. A good rule of thumb is buy as little as possible, use it immediately, and dispose of any surplus.


Politely, may I suggest you look at the book "Primitive Photography" by Alan Greene, and consider doing casein negatives instead of collodion? There are very few milk explosions in a year.

[Paul Fitzgerald]

C.J.,

You can mix 1 tbsp. baking soda with 2 oz. vinegar in a 2 qt. tumbler. When it stops fizzing, 'pour' the CO2 into the ether container, it's heavier than air and will displace the oxygen. Works well for photo chems., paints, varnish, ect. Don't pour in the liquid, just the vapor.

Have fun with it.

[Struan Gray]

Just to reiterate: do NOT store ethyl ether in a domestic fridge, or even a normal laboratory fridge. It evaporates too easily, even at fridge temperatures, and is a significant fire and explosion hazard. The saftey lecture at the lab where I did my PhD always started with an open bottle of ether being put into a fridge (outside on the lawn). At the end of the lecture the door would be opened by pulling on long string and there was always a satisfying bang as the switch for the light sparked and ignited the ether fumes. You wouldn't want to open that door with your hand.

There are specialised fridges for the storage of flammable solvents, but for ethyl ether an outdoors metal cabinet will suffice.

[David Beal]

Jane, do NOT buy gallon bottles of ether. First, what you're buying is not anhydrous, even if it claims to be. It might even be "solvent grade" ether, which is not very clean. Second, glass breaks. A gallon of ether produces a massive amount of vapor, and it dissipates quickly; it also finds ignition sources quickly.

Buy your ether in metal containers, containing less than 1 liter. These should be marked "ACS Reagent Grade." They are sealed with soft metal, and have a plastic overcap.

CAREFULLY puncture the metal cap with a NONSPARKING metal tool, and cap immediately with the overcap. Then, pour out what you need, and use it IMMEDIATELY. All your work should be done in a well-ventilated area, and the ventilation equipment should be certified to be safe to use with flammable vapors. Electrical switches and lights should also be explosion rated.

Your work should not involve any metal trays or tools. Use plastic or glass ONLY.

When you finish your work, take the waste ether and the can of ether outside and pour all the ether into a large tub of water. The ether will evaporate quickly. Fill the can up (even if you used up all the ether) with water, and pour the contents into the tub. Repeat 3 times. Fill the can up with water one more time, and let it sit outside until the water evaporates.

Peroxides are a dangerous and constant problem with ether.

As noted, DO NOT store ether in any kind of refrigerator, even if it in a sealed metal container. Make sure you DO NOT do any work in a basement or area where there might be a water heater or furnace; a pilot light or spark ignitor could cause an explosion.

In my old lab, we worked with ether in fume hoods. The lights in these hoods were enclosed in vapor-proof glass, and the hood was fitted with explosion proof switches.

If this seems like overkill, it isn't. Until you've see how easily an ether explosion can occur, you won't believe it. The old photographers who made plates and didn't get burned up or blown up were incredibly lucky. You may not be.

As a Ph.D. student I worked with Hydrogen Fluoride and Metal Fluorides and made acids that were one hundred million times more reactive than concentrated sulfuric. I synthesized carcinogens and chemicals that were neurotoxic, and studied their reactions with this superacid. I was always very, very careful.

But when it came to using ether, I was fanatically careful.

Good plating.

/s/ David Beal

[Joe Smigiel]

Mike Gudzinowicz stated:

"You can acquire ethyl ether stabilized with ethanol which slows peroxide formation, or you could add 3 to 5 % ethanol to the ether (v/v)... Generally it is better practice to buy small quantities of stabilized ether, dispose of the unused portions of opened containers after a few months, and wash the can or bottle repeatedly before disposal. You really don't need "pure" ether for your purpose."

Whew. The ether-peroxide storage problem sounds scary.

I've skimmed a couple collodion manuals looking for some reason to keep the pure ether around and the only thing I can find is out of John Towler's The Silver Sunbeam regarding the formation of ridges and undulating lines on the finished plate:

"These are caused by the too great consistency of the collodion... The remedy is to add sufficient ether to cause the collodion to flow smoothly, easily, and uniformly over the plate."

So it sounds like there is little use for the ether after the initial mixing of the working salted collodion formula, certainly not enough for me to keep it stored about. Most other remedies involve adding more ethanol or an acid to alter the properties of the working solution. Based on this it sounds like it is best to mix the working solution and then safely dispose of any remaining ether instead of attempting to store it. It also would appear one needs to initially acquire less than half a volume of ether compared to the plain collodion amount.

A typical formula for a working wetplate collodion is:

part A:
1.5 gm cadmium bromide dissolved in 3ml distilled water + 2 gm potassium iodide + 100ml pure grain alcohol (190 proof ethanol)

part B: 120 ml plain collodion +50ml ethyl ether

To make a working solution part A is added slowly to part B.

So, if the percentage of ether in a plain collodion is assumed to be about 70 % (from an MSDS) and about 25% ethanol, the working solution above figures to contain roughly about a 49% ether: 47.6% ethanol mix (134 ml ether and 130 ml ethanol in the 273 ml working mixture). This is a much larger percentage than the 3-5% alcohol ratio you suggest adding to the ether to stabilize it. It sounds like such an amount of ethanol would perhaps greatly slow down the rate of peroxide formation making it much safer to store and perhaps giving the opportunity to use up the small amount of mixed chemicals within a years time. If I'm reading you correctly, the mixed working solution of collodion would be much safer than having the separate chemicals in storage. Can you comment on that?

Also, what do you consider a "small amount" of these chemicals?

What do you recommend for storage of the mixed working solutions of collodion ?

Thanks Mike and David, et al, for the advice and comments.