Vinegar and brown paper

April 18, 2014 2:11 PM

My son added a clothes peg (plastic with a steel spring) to a bucket of cider vinegar. Is the vinegar still safe?

I have 2 gallons of homemade cider vinegar in the shed. About two months ago, I discovered a plastic clothes peg at the bottom of the bucket.

I removed the peg and rubbed the spring with my thumb to see if there was any corrosion. The spring had developed a dark crust that disintegrated as I touch it.

I have no idea how long the peg had been in there. I do not know what kind of plastic it is made of, nor what particular metal the spring is.

The vinegar smells delicious but looks darker than I had expected.

Chemistry experts, is this vinegar safe? Or has the bucket of vinegar become a bucket of poison?

posted by popcassady to Science & Nature (19 answers total)

Metals naturally gain a kind of minor patina due to exposure to oxygen, and the vinegar probably chemically altered some of that. I wouldn't worry, though; the metal is almost certainly steel, and probably not in a bio-available form even after exposure to acid. At worse, the vinegar contains a little iron and carbon, which are two things that're already reasonably common in your body. (Well, you've got an assload of carbon, but only a nail's worth of iron.)

Plastic of that sort is even less vulnerable to a mild acid like vinegar.

I'm not an expert, but I wouldn't hesitate to use the vinegar.
posted by Sunburnt at 2:52 PM on April 18, 2014 [2 favorites]

I wouldn't hesitate to use that vinegar. For cleaning.
posted by oceanjesse at 3:21 PM on April 18, 2014 [1 favorite]

I would use it for cleaning or catching fruit flies, but not to eat.
posted by Chaussette and the Pussy Cats at 3:23 PM on April 18, 2014

Response by poster: oceanjesse and Chausette…, why do you draw that conclusion?
posted by popcassady at 3:30 PM on April 18, 2014 [1 favorite]

Assuming your vinegar was safe in the first place, I don't think a tiny amount of rust/corrosion would make it toxic. I think the acid just accelerated the corrosion and made it look scary.

I'd keep it.

(Not chemistry expert. Also not afraid of rust.)
posted by zennie at 3:49 PM on April 18, 2014

I wouldn't eat it because I don't know what the hell is in it besides vinegar, and neither do you.
posted by oceanjesse at 4:23 PM on April 18, 2014 [3 favorites]

My brain says that vinegar is acidic and rather inhospitable to tiny bacterial creatures and would taste test then shrug it off. Though I'm not a scientist and occasionally eat things left on the stove cold overnight.
posted by AlexiaSky at 5:00 PM on April 18, 2014

It isn't bacteria that you would worry about; Vinegar is an acid and great at dissolving metals. You don't know what type of metal the spring was made out of, and as you've said, it changed colour. That probably means that you've got dissolved metal in your vinegar. Now, if that is say, iron, you are probably fine. If that is lead or tin, that is much less fine.

It will always smell fine, unless you add base to it. The smell is just the smell of acid, and most of them smell like that; I can't tell vinegar and hydrochloric acid apart by smell, except one is a lot stronger then the other, and I sure wouldn't want to cook with HCl.

Vinegar isn't that expensive, why risk it? Use it for cleaning, it works quite well for that. Or dissolving chicken bones in for a science experiment or something.
posted by Canageek at 6:12 PM on April 18, 2014 [4 favorites]

Apple cider vinegar can sometimes get darker over time, while remaining perfectly fine.

It's true you don't know what the composition of the spring was/is (although I really can't see the sense of using lead in a spring). I think it's likely steel wire and a small layer rusted off, but there's no way to know without a lab involved. If that uncertainty bothers you now and will continue to bother you, then toss it and make some more.
posted by zennie at 7:29 PM on April 18, 2014

You do know what the spring was made of; it was made of steel. I would be fucking shocked if it were anything else. It was made of mild steel, which is iron with some carbon in it, because that is the cheapest appropriate material for a spring of that kind. It was a silvery-gray metal, which means either steel, aluminum, or some exotic alloy (titanium, chrome-vanadium, tungsten carbide). Steel is the cheapest and it would work, so that's what it is.

Your vinegar is surely safe to drink; vinegar is quite inhospitable to microbes, and there's nothing toxic in a clothespin. If it tastes OK, I wouldn't worry about it. If it tastes odd, use it for cleaning.
posted by Scientist at 8:35 PM on April 18, 2014 [9 favorites]

I would not eat it because I avoid eating rust, metal and tiny, tiny bits of plastic.

I don't microwave plastic either. If you microwave plastic, you could probably eat it.
posted by Chaussette and the Pussy Cats at 8:41 PM on April 18, 2014

Yes!
posted by telstar at 11:33 PM on April 18, 2014

Oh god yes, I wouldn't even think twice. Steel is no problems, plastic wouldn't corrode and if it did would go straight through you.
posted by smoke at 12:07 AM on April 19, 2014

I would not drink it or use it for cooking. I would suspect that the steel wire spring on the clothespin has galvanized plating which would be dissolved in the acidic vinegar.
posted by coldhotel at 8:48 AM on April 19, 2014 [1 favorite]

Response by poster: I would not drink it or use it for cooking. I would suspect that the steel wire spring on the clothespin has galvanized plating which would be dissolved in the acidic vinegar.

Is galvanised steel easy to differentiate from non-galvanised steel? The springs of the clothes peg's siblings have surface tarnishing -- is that typical of galvanised steel?
posted by popcassady at 9:23 AM on April 19, 2014

Do you know that he added the clothes peg and nothing but the clothes peg?
posted by The corpse in the library at 9:54 AM on April 19, 2014 [4 favorites]

I tend to agree with the others who say that the problem is not the clothes peg, the problem is not knowing what else might have gone into the bucket besides the clothes peg.
posted by jacquilynne at 10:15 AM on April 19, 2014 [1 favorite]

Response by poster: Thanks for all your thoughts. I've decided to err on the side of caution and keep it away from our plates.
posted by popcassady at 4:03 PM on April 19, 2014

Galvanized steel has been coated with zinc to give it better corrosion resistance. Zinc oxidizes more slowly than steel, and zinc oxide is white rather than the red of iron oxide. If the springs of the sibling clothespins are "tarnished", i.e. they have a dark reddish-brown color to them, then they are not galvanized.

That is to be expected; galvanization costs money, and most buyers of clothespins probably would not pay extra for it. Galvanized steel is the second cheapest appropriate material for a clothespin spring, and while I bet there are some such clothespins in the world, they're probably rather unusual.

By the way the vinegar probably cleaned off the rust on the clothespin that went into it. The extra H+ ions in the vinegar (vinegar, like all acids, has lots of free hydrogen cations floating around in it) would really love to team up and pull those oxygens off of the iron oxide and turn themselves into water molecules. This would bring the iron into suspension in the vinegar, giving it that brown color you mentioned. It would probably also impart a metallic taste, if there were enough of it.
posted by Scientist at 6:12 PM on April 21, 2014