Hand-wash your lunch box

Most lunch boxes should be hand-washed, even if the label hints otherwise.

The main body — stainless steel or a plain plastic shell — usually survives a dishwasher cycle fine. The problem is everything else: the lid, the silicone seal, the locking clips, the little removable dividers. That stuff is often polypropylene or a softer plastic that warps under high heat, and the gasket degrades faster, which means leaks later.

The one thing you definitely shouldn’t put in there is any insulated bottle or thermos-style container. The extreme heat can break down the vacuum seal between the walls, and then your “insulated” lunch box becomes a regular lukewarm container. Silicone parts are usually dishwasher-safe, but if you’re not sure, don’t gamble on it.

The truth is, a lunch box takes thirty seconds to wash by hand. The dishwasher might save you a minute but costs you a replacement lid down the road. That’s a bad trade.

Your leak-proof seal is not where you want to save time.