Sciencemadness Discussion Board

Gas masks

tryptic - 4-8-2004 at 11:03

Hi all

I'm planning for a largish organic synthesis with maybe 500 ml of methanol as a solvent.. Assuming I don't have a decent fume hood, just a couple of windows open, is it wise to use a gas mask when working with this amount of methanol? Probably..

Any experience with gas masks, are they a major pain in the ass when doing lab work?

On the other hand, now that I think of it, maybe I could make a pretty good fume hood from an old vacuum cleaner! Could be a lot more convenient.

[Edited on 4-8-2004 by tryptic]

axehandle - 4-8-2004 at 11:23

I don't think a gas mask would filter out methanol -- it's a very small molecule. Feel free to correct me if I'm in the wrong.

tryptic - 4-8-2004 at 11:27

You just need a special filter for methanol, and the manufacturer also says that you can only use a methanol filter for one work shift..Check out for example

Type AX filter is for methanol..

axehandle - 4-8-2004 at 11:30

Ok, I'm probably erring on the safe side, but the product info doesn't say anything specifically about methanol, just "organic compounds with boiling point below 65°C".

Ok, I'm blabbering, but I'm scared of methanol...

tryptic - 4-8-2004 at 11:35

The scottsafety web site seems to go through a region-specific proxy, but at least from where I am looking, there's a link below the image of filters which says "Literature as PDF-file. Download here". At the bottom of that document there's a list of which chemical needs which filter..

[Edited on 4-8-2004 by tryptic]

axehandle - 4-8-2004 at 11:40

Ok, sorry, I was wrong and overreacted. I just had this mental image of you going blind from methanol vapors, and panicked.

[Edited on 2004-8-4 by axehandle]

tryptic - 4-8-2004 at 11:42

Heheh yeah this is kind of risky stuff :D


No chatting. Chatting = U2U.

[Edited on 4-8-2004 by vulture]

bennator - 4-8-2004 at 13:23

I don't know what else you are working with, but I happen to be spending my summer in a proteomics lab, and we work with greater than 500 mLs of Methanol just out on the bench often, and I've never seen anyone wear a mask or anything.

tryptic - 4-8-2004 at 13:57

Thanks for the info!

Yeah, I did some rough calculations myself and I also came to the conclusion that with a couple of windows open the ventilation will probably be good enough that I don't need to worry about it too much. There will be some amount of methanol in the air but still a pretty big safety margin before the 200 ppm recommended limit. I'd guess a factor of 5 safety margin at least.

MSA Comfo Classic

Magpie - 7-9-2004 at 18:59

I just used my new gas mask and am quite pleased with it. It is an MSA Comfo Classic which takes 2 ea screw-on flat cartridges. I installed the "Chemical Cartridge, GMA type." These are "NIOSH approved for respiratory protection against organic vapors, chlorine, hydrogen chloride, sulfur dioxide, chlorine dioxide, and hydrogen sulfide (escape only)."

I painted a work surface with epoxy paint. From the moment I put the mask on I never smelled anything. The paint contains: "petroleum distillates, xylene, dipropylene glycol MM ether, propylene glycol mono ether, 2- butoxy ethanol, and epoxy resin." I then wore it while cleaning the brush. First I used toluene, which didn't work, then lacquer thinner, which did. The lacquer thinner contains "methanol, toluene, acetone, glycol ether, petroleum distillates, ketones, and esters." Again I smelled nothing.

I also bought a box of P100 cartridges. These are HEPA type filters for capturing particulates and aerosols." I'm planning on using these when working on my fire assay for gold where lead fumes will be generated. I'm also going to set the furnace up outside and have some type of forced draft hood with a HEPA filter. You can tell I'm really spooked about these lead fumes.

Hermes_Trismegistus - 7-9-2004 at 23:10

Originally posted by axehandleOk, I'm blabbering, but I'm scared of methanol...


Seriously, I cannot remember exactly how it works, but the most serious danger associated with it is the reaction that occurs with a nerve in the back of the eye. However, ethanol interferes with the effect by occupying the same location. Still, with methanol, the only danger comes when it occupies more than ~40% of the blood alchohol and is in serious quantity.

If you drink methanol admixed with about 2/3 ethanol you are quite safe, (from acute damage from methanol toxicity)

Chronic exposure causes liver damage, but you can damage (or even surgically remove) up to 80% of the liver and it will regrow within 18 months (saw that on A+E)

There is a gang in Winnepeg called the "Indian Posse" that uses this trick as a macho thing, mixing methanol, methyl hydrate or ethylene glycol with overproof vodka and drinking the concoction.

(saw this on W5 documentary)

The purpose is to look tough to non-members, the reality is that members of the gang often get so drunk they screw up the ratio, and sometimes they run out of vodka before they want to stop getting drunk, so they take a shot or two of straight methanol rationalizing that the extra ethanol (2/3 ethanol-1/3 methanol remember) is enough to protect them and stay within the "magic" 60% ethanol.

Sloppy drunken assholes fuck up, drink so much that they don't have one or two at the end, they have four or five or ten. And wake up in the hospital blind as a bat with severe liver damage.

So....long story short.... drink perhaps 100 ml's of ethanol prior to running the reaction.

And try not to light yourself on fire or blow yourself up, because that's the real danger of working with methanol.
(fire extinguisher)

Didn't orgi send you some wodka?

vulture - 8-9-2004 at 07:50

Hermes, were you drunk when you wrote this?


So....long story short.... drink perhaps 100 ml's of ethanol prior to running the reaction.

100ml of ethanol, I'd like to see anyone conduct an experiment after such a quantity


Hermes_Trismegistus - 8-9-2004 at 08:01

100 ml's is ~ 7 tablespoons eh?

maybe it might be a little bit of a shock if it was taken as a single gulp, or in the form of 98% etoh, but I don't realy see this as unrealistic, but maybe that's just cause I'm Canadian?

Edit: in case you live in the U.S. the conversion rate is about 2 bottles of la fin du monde to 11 gallons of budwieser :D

[Edited on 8-9-2004 by Hermes_Trismegistus]

neutrino - 8-9-2004 at 13:46

Originally posted by Hermes_Trismegistus
If you drink methanol admixed with about 2/3 ethanol you are quite safe, (from acute damage from methanol toxicity)

Are you sure about this? Denatured alcohol has to be undrinkable to avoid taxation, and I think that the stuff they sell OTC is a lot less than 30% MeOH.

axehandle - 8-9-2004 at 14:26

Can't speak for the law where you live, but it sounds like it is here: Undrinkable alcohol is tax-exempt. Noteworthy is that "undrinkable" doesn't necessarily mean "impossible to drink", it probably means "extremely yucky to drink". 98% OTS alcohol here only contains about 95% ethanol -- the rest is ethyl acetate, acetone and a flavor agent called Bitrex to give it that... memorable.. taste.

Not too sure that the 30% figure is true though -- they tried to replace the 98 with a 90/10 EtOH/MeOH mix a decade ago but had to retract the product, I remember something about people dropping like flies because they drank it. Could be another reason though I suppose...

For those of us on the brink of chronic alcoholism though, it's entirely OK to drink 98%, just as long as you drink some water immediately after and stay away from ignition sources.

100ml isn't much, it was only a few months ago I had a healthy swig containing, incidentally, that exact amount. Gave a warm fuzzy feeling in my guts. YMMV though...


Hermes_Trismegistus - 8-9-2004 at 15:17

We present the case report of a 47-year-old man fatally poisoned by ingestion of a home-distilled liquor produced from 'methylated spirits' containing 5% methanol and 90% ethanol. Classical signs of severe methanol poisoning, including altered conscious state, shock and profound acidosis were manifest at the time of presentation. Despite an ethanol infusion and haemodialysis he was declared brain dead 36 h after arrival at the emergency department.

apparently it isn't a perfect treatemt regimen.

I did found out why ethanol is used as a treatment though.

Methanol is most dangerous because of it's metabolite. Formic acid is produced when the metoh is metabolised by alchohol dehydrogenase ethanol eats up a significant percentage of the dehydrogenase and slows down it's metabolisis.

In a person with strong kidney function, If the pH is low the kidneys raise the blood pH towards normal by excreting acid H + Cl , NH4 + Cl or 2Na + Cl + H2PO4

If your kidneys are weak, or you strongly produce alchohol dehydrogenase, you die.

Final verdict:There is no "safe" dosage for methanol in the blood.


Hermes_Trismegistus - 8-9-2004 at 15:21

So that's why the indians can do it! They have extremely low levels of Alchohol Dhydrogenase!

missing gene

mick - 9-9-2004 at 13:41

The filters work, I used them when I use to spray 2 pack paint, isocyanates, with a big fan.
If you are used to drinking ethanol, methanol is not a problem but some people can not drink ethanol so methanol is very dangerous to them.
If you use BP grade ethanol no one gets a headache from alcohol if you mix it with fruit juice but every one is pissed and happy
If you do not drink ethanol, methanol is a acculamtive poison. I could be wrong though.

Forget the nuff sed
nuff sed

[Edited on 9-9-2004 by mick]

[Edited on 9-9-2004 by mick]

[Edited on 9-9-2004 by mick]

neutrino - 9-9-2004 at 13:46

Actually, all hope may not have been lost.

Originally posted by Hermes_Trismegistus
home-distilled liquor produced from 'methylated spirits' containing 5% methanol and 90% ethanol.

I'm guessing that the 5% MeOH was the original concentration before distillation. If distilled, mostly MeOH will come over first, and assuming that he drank that part, the actual concentration would have been much higher than 30%.

edit: typos

[Edited on 9-9-2004 by neutrino]

I am not certain.

Hermes_Trismegistus - 9-9-2004 at 16:18

Research on this subject met with many conflicting sources of information and anecdotal evidence, even that published in credible news reports can be faulty.

In the interests of Axehandles' health a more reliable method must be found. A method that is both economic and efficacious.

Methanol is entirely miscible with water; correct?

I propose that during times of acute exposure a Hookah is used.

Yes, a hookah, a waterpipe, a bong.

The incoming air could be bubbled through icewater. In theory the methanol vapours would condense into the water and stay locked in until the azetropic concentration was reached. If the water was extremely cold the evaporation of the water/methanol mixture would be quite low.

This method would be, admittedly less than ideal, however it would also be very low in cost and the "refills" of the absorbant "cartridge" would be quite affordable.

Gas mask help/info

Quantum - 12-9-2005 at 17:43

I have gotten my yearly funds for chemistry(aka birthday money:D) and I wish to buy some simple equipment, some chemicals and some nice quickfit. I also want to be safe and get a good gas mask.

I understand the ones at are very good and I can afford one of the simpler models but my question is thus:

Having a 40mm NATO NBC filter is all well and good and will save me from NBCs and regular lab chemicals like acid gases, organic vapors ext. Now I'm not really too worried about NBC shit but I don't want to have to shell out lots of green every time I use up a filter. Are there 40mm cartriges that will just provide regular protection yet also fit on the real gas mask platform as apposed to some lame halfmask? I have searched and found nothing - please reply

It's been more then 6 months! I have to bump

Quantum - 5-6-2006 at 13:09

Please all people with gas masks read this and my above post. I have saved over 100 bucks and I want to get a good gas mask but I really don't need NBC filters for simple lab work. So is their a way I can get a nice gas mask that uses cheaper industrial filters and can also use NBC filters?

franklyn - 2-5-2009 at 23:40

There has been some interest expressed from time to time for
obtaining quality filter masks here and in this other thread too ,

I just got a new Finnish army mask for $ 19.50 that comes with - 2 -
filter cartridges sealed in plastic. Those alone are worth the price.
The mask is tagged from 1996 and aside from a dusty exterior
which is surface oxidation , the rubber is in fine shape.

available here _

item 39008.jpg - 14kB

Sauron - 3-5-2009 at 23:24

Surplus military gas masksmay be fine as fetish accessoroes for rubber pervs, but they are generally worthless for lab use

The rubber is old and permeable and the filters are shot,

If you NEED a respirator by a new commercial one tailored to yur threat,

If you eed a SCBA even better.

Why not just install a proper fume hood?

Few need anything else.

panziandi - 4-5-2009 at 13:13

Actually I have been tempted to get one for exactly that reason, thanks for letting me know they are well suited Sauron!

On a more serious note though, sometimes (orgsyn etc) recommends using a gas mask aswell as manipulating under a hood. I suppose added protection isn't always a undue. But indeed for most things I would have expected a fume hood to surfice, especially in most amateur settings, atleast the fumes are removed from the surroundings rather than just removing them from the air you are breathing....

Really Cheap Gas Masks

franklyn - 5-5-2009 at 23:18

How can you go wrong, at these prices you can't afford to be without one.

$ 8.99 each , 3 for $ 24.95

$ 11.99 each , 3 for $ 29.99

Masks have the virtue of being portable so that fuming procedures
can be done in the great outdoors, or lacking this, on a rooftop.
There is nothing inherently " degradable " about activated charcoal
that imposes a shelf life on a canister providing the seal is intact.
The canisters I received are dated 1987 which predate the mask
by 9 years. Since these were retired together, that should tell you
something of expected service life. Military issued goods are of very
high standard and often discarded in perfectly good condition.
Here is an outline of what the CDC considers in its evaluation of
mask design, and specifications. I doubt the Fins would do any less.

There is no shortage of people willing to have you pay excessively
for goods of comparable utility with no guarantee that paying much
more gets you anything markedly better suited. Anyway read the
feedback yourself I'm sure there are former servicemen among them
that can critically evaluate their purchase.

Fit of a mask and how it seals is what matters , as I said before
Proper Fit Checks

Positive Pressure Check
Cover the exhalation valve with your hand and exhale gently into the face piece. If a
slight positive pressure is built up inside the face piece without any evidence of
leakage, the fit is satisfactory. This test method is the most widely used to check
proper fit in the field.

Negative Pressure Check
Close off the air inlet valves (i.e., cover the cartridges with your hands), inhale gently
to collapse the facepiece slightly, and hold your breath for 10 seconds. If the
facepiece remains slightly collapsed and no leakage is detected, the respirator fits
properly. It may be difficult to get a good seal when trying to cover the inlet valves

So why so cheap ?
I omitted to say in the post before that these are discontinued
60 mm canister masks whereas the NATO and commercial standard
is now 40 mm.

Small matter you can obtain adapters also.
60mm -> 40mm adapter
40mm canisters and 60mm adapter package deal

These canisters are cheap enough that if one really wants to test
their efficacy its a simple matter to attach one to a vacuum and
draw NOx or Chlorine through it and test for its presence coming
Any canister has a useful service of 6 to 8 hours at a minimum although
recommendation for replacement can be as little as 2 to 4 hours of
exposure to gas contaminants. Assertions that their utility is measured
in minutes invokes concentrations that would dissolve your skin.
Re-use of filter canisters depends on how long you plan to keep one
after its fiirst use. I'd say it should be used within 6 to 8 months after
first use providing it was hermetically resealed in plastic during that
Re-usability study

MIL-1200.jpg - 22kB

Sauron - 6-5-2009 at 00:34

I doubt that OS meant an out of date surplus mask with spent AC filters and rubber all shot to hell.