Put the dressing in its own zip-top bag, then set it upright

Put the sauce bottle in its own sealed plastic bag and keep it standing upright. That’s the whole trick.

Leaks happen because the bottle gets jostled, the cap shifts, or something crushes it. A zip-top bag contains the mess before it reaches your sandwiches. Even better: wrap the bottle in a paper towel first, then bag it. The towel catches drips and keeps the outside dry.

Don’t lay it flat. Stand the bottle up next to the cooler wall or tuck it between other rigid containers so it can’t tip over. And don’t bury it at the bottom — put it on top of heavier stuff so it doesn’t get squashed by a thermos.

If you use a glass bottle, the bag is also your safety net for breakage. You won’t end up with glass shards in the potato salad.

Future you will thank you when the picnic blanket stays clean.