In article ,
says...

On 13/05/2012 14:49, Don Phillipson wrote:

Conditions are obviously different in Ontario, Canada, where

household vinegar (5% acetic acid) is an effective weed killer
on our gravel driveway.

I find that very hard to believe. On limestone gravel it will be
netralised on contact.
It might just about work on a good day in full sun on particularly
feeble weeds.

Just a guess; wouldn't sub-zero winter soil temps in Ontario probably
kill any shallow rooted annual and perennial weeds on a gravel drive (laid
over a solid subbase, and kept clear of insulating snow). So in the
growing season there would only be newly germinated seedlings which are
very vulnerable.

Janet