Cookie jars come in shapes and sizes of all sorts: You can buy one that looks like the Cookie Monster, Tinker Bell, or Mr. T. But what about function? We want our jar to keep cookies fresh, intact, and easy to grab. Avoiding novelty jars, we bought four models, one each in glass, plastic, ceramic, and stainless steel, all with at least 4-quart capacity so they could hold plenty of baked goods.
We looked for jars with a tight seal to maintain freshness and with openings wide enough to allow us to reach inside for really big cookies (up to 4 inches in diameter). We filled the jars with French tuile cookies (they’re brittle, so particularly susceptible to humidity) and inspected them daily for a week: Even the worst performer kept the cookies crisp for a respectable four days. Next we filled each jar with a moisture-sensitive color indicator called Drierite; its crystals change from blue to pink as dampness penetrates. After seven days, we noticed changes in color, which were more drastic in some jars than in others. Only one jar, the OXO Good Grips Pop Storage Container, kept the Drierite blue. It made an airtight seal that can keep our homemade cookies fresh, crisp, and delectable for days—if they last that long.