Take the silicone seal out before you wash anything.

The most effective way to clean the crevices and silicone seals of a bento box is to pull the seal out, soak the parts, and scrub the grooves with a small brush.

Most bento seals pop right out, and you should take them out every single wash. If you don’t, food particles and oil get trapped between the seal and the groove — and that’s exactly where mildew starts. It takes two seconds, do it.

Soaking does more than scrubbing. Warm water with a squirt of dish soap, let it sit for ten minutes, and the gunk in those seams loosens on its own. Then hit the grooves with a straw brush or a small bottle brush. An old toothbrush works great for the tight corners.

The part everyone gets wrong is drying. Silicone holds moisture against the plastic, so if you snap the seal back in while it’s still wet, you’re sealing water inside. Let everything air dry fully before reassembling. If you caught it too late and it smells, a vinegar soak fixes that.

Mold doesn’t care how cute the bento is.