I remember someone mentioning there was a better time to spray so that the green leaves absorb the liquid but I cannot seem to find it in the archives.
@Angela K- BAD NEWS...Your Hands ! I put a book on cd and sit down and commune with nature ! LOL It is a pain but when done thoroughly at the beginning of the season, that takes care of it, for the most part. I always wait and put down my new mulch afterwards, then DONE! I have gravel paths around my flower beds. That is where I use it. Also where you would have pavers.
You can use the 5% or 9% white pickling vinegar found on grocery store shelves. It will probably be plant based. You can also find 20% strength which will probably be petroleum based but is still better to use than Round Up. Add 2 ounces (4 tablespoons) of orange oil plus a squirt of liquid dish detergent. (That helps it stick to the plant.) Use in the hottest part of the day.
I have tried the vinegar solutions and have had limited results. If you are killing tough weeds especially some that tend to be woody or have a waxy coat on the leaves, Roundup brings good results. It is impractical to try to use home remedies when you are doing large areas. Just be responsible and use as directed to prevent damaging surrounding plants.