squeaky clean?

May 22, 2009 10:59 PM

Washing the dishes with methylated spirits. Is this dangerous?

My father-in-law insists on putting a splash of methylated spirits into the dishwater. Surely this is a poison and shouldn't really be anywhere near my food? He claims it helps them dry better and kills germs etc...he is very germ-phobic. Am I right in thinking that this isn't really a good idea?

posted by robotot to health & fitness (13 comments total)

I'm not a doctor or a chemist (although I took organic chem last year) But I don't think it's going to matter. I also don't think it's going to help with cleaning much.

The problem with denatured alcohol is they've got methanol instead of ethanol. It's Bad. But both of these are going to evaporate very quickly. It's not going to get into your food.
posted by floam at 11:07 PM on May 22

You won't be eating it, but you'll be breathing the vapors. Probably not enough to matter, though. How much is "a splash"?
posted by ryanrs at 11:15 PM on May 22

The real problem is the fumes, a little can go a long way. I've seen guys get pretty severe headaches (IE: posioned) from using methylated spirits for shellac. The methanol (if that is what it is cut with, there are other adulterants) will form a solution with the water reducing the amount inhaled though. No significant residue will be left on your plates but I doubt it's doing much more than plain dish soap and hot water to kill germs.
posted by Mitheral at 11:28 PM on May 22

It doesn't seem to me that it'll do much good or harm. It'll be way too dilute once mixed with the dishwasher water to act as a germicide, and it seems to me that after the wash and rinse cycle it'll all have been washed away so it can't really help with the drying. Unless "a splash" is a lot more than I imagine it is, it doesn't seem like very much vapor is going to escape the dishwasher (does it make the kitchen smell like alcohol?).
posted by hattifattener at 11:39 PM on May 22

According to http://en.wikipedia.org/wiki/Methanol

"In some wastewater treatment plants, a small amount of methanol is added to wastewater to provide a food source of carbon for the denitrifying bacteria, which convert nitrates to nitrogen to reduce the denitrification of sensitive aquifers."

It might actually be causing bacteria to grow!
posted by bottlebrushtree at 11:55 PM on May 22 [1 favorite has favorites]

According to the wikipedia, meths is mostly ethanol with methanol added to make it unsuitable for drinking.

At that concentration, I forsee no problem.
posted by gjc at 12:05 AM on May 23

If you've ever cooked with a methyated spirit powered camping stove, you will know all about how foul a small amount of metho spilt on your plate will make everything taste. If he's not using enough to make his food taste bad, the worst he's doing is wasting a bit of metho. Not a problem I'd bother trying to solve.
posted by flabdablet at 3:12 AM on May 23

It's worth pointing out that dishwasher detergent is pretty toxic in and of itself. All kinds of nasty ingredients, up to and including bleach. Not the kind of stuff you want to be eating, that's for sure. But no one (almost no one anyways; there are people who are paranoid about it) worries about this, because it all gets rinsed off pretty effectively.
posted by valkyryn at 6:41 AM on May 23

It isn't dangerous, it's just stupid. He might as well be throwing in kool-aid or a spritz of bleach for all the good it'll end up doing once it's diluted in gallons of wash water and then rinsed away.

Hasn't he ever heard of Jet Dry?
posted by JFitzpatrick at 8:37 AM on May 23

You can't change his mind about using methanol, so don't bother.

But just tell him to keep the area well ventilated to minimize any side-effects from inhaling vapours -- I imagine that's an easier battle to win.
posted by randomstriker at 10:29 AM on May 23

At that concentration it's doing nothing. Not killing germs, and not killing you.
posted by Jilder at 10:29 AM on May 23

I'm not a chemist...well, actually I am, but I'm not your chemist...uh, that doesn't make sense, does it?

Anyhow, if your using alcohol to sanitize things in a lab you usually use 40% or 70% solutions. Dropping a rock taped to a penny into your dishwater would be equally effective as a splash of alcohol (particularly if it's, uh, my piezo-cuprich healing device that I'll hastily cobble together as soon as your check clears the bank!) In terms of total risk, volume to volume there's probably an equal amount of methanol in an orange (depending on what you mean when you say a splash) so he's probably not doing himself any real harm.

The biggest danger is that he's got a can of something highly flammable in the room with the stove.

If he's really that worried, an ounce or so of bleach in cold rinse water might actually do some good, but only if it you let things soak for a few minutes. That's what home brewers do with their equipment prior to use.
posted by Kid Charlemagne at 5:46 PM on May 23 [1 favorite has favorites]

Thanks everyone, I figure it's not dangerous, just seems like a bit of a hill-billy solution to a problme made up by a paranoid germamphobe. He's too set in his ways to be talked out of doing it, but at least it's not as harmful as I'd imagined. Maybe I should be more concerned with the amount of chlorine he puts in the tankwater - every time I have a shower at his house I end up smelling like a public swimming pool.
posted by robotot at 8:57 PM on May 23