How can I get my hands on higher-concentration vinegar?

February 23, 2008 4:33 PM

How can I get my hands on higher-concentration vinegar / acetic acid?

I've seen a number of articles about using vinegar as a low-environmental-impact weed killer. Most of the studies/tests have used vinegar at higher concentration than household/cooking vinegar (5%?). So how/where can I get my hands on that?

posted by madmethods to Home & Garden (11 answers total)

I've seen a German brand of 25% vinegar sold at Whole Foods - can't recall the name at the moment, though. There's a big warning on the bottle to dilute before using.
posted by deadmessenger at 4:43 PM on February 23, 2008

You know, I was going to suggest boiling the vinegar (at less than 118° C, the bp of acetic acid) but that would be a bad idea for several reasons.

1) Acetic acid is a corrosive irratant. When the fumes come into contact with your mucous membranes, it won't be pleasant.

2) Acetic acid is flammable, and while the concentrations you're working with are likely not a fire hazard, the more you concentrate it, the greater the risk.

So don't boil it. Local chemical supply companies will very likely have concentrated acetic acid available.
posted by chrisamiller at 4:50 PM on February 23, 2008

If you can't find high-strength vinegar, I imagine phosphoric acid rust converter would do the job by much the same mechanism. Once the burned ground had been rained on a few times, you'd get amazing regrowth rates from all that phosphate, too.

Or you could just use glyphosate, which has much less impact on everything except plants.
posted by flabdablet at 4:58 PM on February 23, 2008

Of course, if you're looking for the ultimate in low-cost environmentally-friendly weed killers, you can't go past urine.

Like most Australian households, every now and then we get a patch of bindii showing up in our lawn. Having found one, I put a little peg in to mark the spot. I wait until it hasn't rained for at least two days, then go and empty my morning bladder on it. Two loads is usually enough to make the bindii go grey and burnt. It doesn't seem to affect the surrounding grass quite as much, though there is a bit of yellowing.

One rain later, and there is quick and very lush grass regrowth over the burnt spot.

I imagine you could do the same with an overdose of just about any high-nitrogen and/or high-phosphate fertilizer.
posted by flabdablet at 5:31 PM on February 23, 2008 [1 favorite]

Old wet-chemistry black & white photo development used acetic acid as a stop bath to kill the developer chemicals. It was available in a concentrate, which you'd dilute as necessary. You can probably get it at a good photo shop that still handles film.
posted by spacewrench at 5:33 PM on February 23, 2008

Oh, and before I finally leave this alone: I've seen Jackie French recommend leaving urine to mature in a warm shed for a few days before using it as weed killer, to boost the ammonia content. But personally I prefer not to have stinky bottles cluttering up the place, as the undiluted fresh stream seems to get the job done just fine.
posted by flabdablet at 5:35 PM on February 23, 2008

You can usually get the high concentration vinegar at independent (non chain) lawn and garden stores. You might also find it at an organic food store - anyplace that caters to the environmentally friendly folks is likely to have it.

I tried using vinegar but found that although it did kill the weeds and grass, it grew back fairly quickly. A light coating of RoundUp Spring and again in mid Summer keeps my fence line grass and weed free all growing season.
posted by COD at 5:59 PM on February 23, 2008

Glacial acetic acid is a common name for water-free acetic acid. You can dilute it to whatever concentration you would like to try. Do be careful with it, and observer proper acid-handling protocol (wear gloves, goggles, work outside or under a fume hood, and always "do as you oughta, add acid to water").

To get an idea on price, you can buy some here and here amongst countless other chemical supply companies.
posted by jedicus at 6:17 PM on February 23, 2008

As above, what you want is GLACIAL ACETIC ACID. I only add--try any local photographic supply places, who probably have a case of the stuff and no idea of how to get rid of it profitably.

Also, while nasty, it is not nearly as nasty as the old standbys: HCl H2SO4 or HNO3.
I recall just pouring the stuff, and I still have the normal complement of fingers and eyes.
posted by hexatron at 6:25 PM on February 23, 2008

Be careful with glacial acetic acid, as it's highly flammable as well as being acid-nasty.
posted by flabdablet at 11:02 PM on February 23, 2008

Asian grocery stores sell double vinegar, which worked for me.
posted by sevenstars at 6:35 AM on February 24, 2008