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Sturdy, stain-proof, and microwavable, glass can be a good choice for food storage, but which container offers the best size, shape, and sealing power?
We don't think home cooks should have to choose between plastic and glass food storage containers, since both have advantages: While glass is heavier and more fragile than plastic, it also resists staining and warping, can go in the microwave without worry, and can even be used in the oven for cooking or reheating, offering great versatility. We tested five glass storage containers alongside six plastic containers (see related story for our plastic container testing results), all with capacities as close as possible to 8 cups, a good size for storing leftovers or a make-ahead meal. Some containers can be purchased a la carte, while others are sold only in sets. For those who purchase glass containers to avoid plastic, we did notice this: Most have plastic lids. Only one model we tested had a glass lid, with a silicone trim to seal it in place.
We put these glass containers through the same series of rigorous tests as our lineup of plastic containers, with the exception of knocking them onto the floor and with the addition of using them in the oven. Our goal was to find a truly airtight, leakproof container, in a size and shape that works well for home cooks, that resists stains and odors, can reheat food in both oven and microwave, and is easy to use and clean.
To keep food at its freshest, you want a container that is airtight and leakproof. If it tips a little in a crowded refrigerator or while you're transferring it from one location to another, you want to be sure it won't spill. And if you happen to be storing very fragrant food, odors shouldn't escape the container. We tested seal quality by filling our containers with water and shaking them in all directions, as well as by submerging them in water with moisture-detecting crystals sealed inside. One failed both tests right away: Its plastic cover lacked the silicone gasket and flaps that most others had to secure the lid, so it simply didn't seal completely. The rest performed perfectly—at least the first time we did this test. But after we'd used and washed them during routine testing and run them through the dishwasher 50 more times to simulate a year of weekly use, two of the four models failed to seal as tightly when we repeated the test, indicating that they might not hold up well over time.
To check whether they would retain smells, we filled the containers with oil-packed tuna and anchovies, refrigerated them overnight, washed them carefully, and conducted a “sniff test.” Only the container that had failed our leak tests, with its loose plastic lid and no gasket, was mostly odor-free; the others revealed the importance of removing and scrubbing gaskets and around lid flaps, whose nooks and crannies were prone to trapping smells. (Two containers' gaskets were large, soft, and easy to pull out; the third was tiny and difficult.) To see if they'd stain, we loaded the containers with chili full of tomatoes and colorful spices. After refrigerating the containers over a weekend, we microwaved the chili still in the containers to a piping-hot 160 degrees. Unlike the plastic containers we tested, these glass versions stayed stain-free, but their plastic lids, which sat atop the chili, did become lightly stained. One container's bright blue lid cleverly masked any stains. The container with a glass lid showed stains on its white silicone trim, but these eventually disappeared with more scrubbing.
We opened and closed each container 200 times, 100 times before and 100 times after our dishwashing tests, reversing the lid position each time. This helped us evaluate how easy each container was to seal and the durability of its construction. None of the lids broke, but some were definitely much easier to seal than others. The worst had extremely tight flaps that snapped down over a raised ridge on the glass bottom. That tight seal never leaked a drop, but it was a little painful for some testers to close. Two others—the one with the simple plastic lid and the glass lid with silicone trim—were easy to put on, but they rarely felt as securely latched as those with snap-down flaps; in fact, these two were the ones that leaked throughout testing. Ultimately, we preferred containers with snap-down flaps and silicone gaskets, and our top choice was comfortable to snap while remaining securely leakproof.
All the glass food storage containers we tested claimed to be ovensafe, a nice bonus that makes them more versatile. However, every product's label and/or website listed extensive warnings about thermal shock, which is when rapid, extreme temperature changes cause glass to shatter. We recommend that you read these instructions carefully before using your container in the oven. In every case, you should put glass vessels into only a fully preheated oven, since ovens preheat unevenly, with much hotter and cooler zones forming until the oven reaches its target temperature; also, never use them under the broiler. While three of the five containers are made of borosilicate glass, a material that is supposed to be more thermal shock–resistant than the tempered soda-lime glass of which the other two were composed, their warning lists were equally long. We used each model, in a preheated oven, to warm up refrigerated macaroni and cheese to serving temperature and had no problems heating or handling any of the containers.
At the end of testing, we had a clear winner. The OXO Good Grips 8 Cup Smart Seal Rectangle Container ($14.99) sealed easily and tightly without letting a drop spill. Its large, soft gasket was easy to remove, clean, and replace, and it emerged from testing in excellent condition. It's our new favorite glass storage container. While we tested the 8-cup version, this model comes in a wide variety of sizes and is sold a la carte and in sets.
We tested five glass food storage containers as close as possible to an 8-cup capacity. Information about the maximum ovensafe temperature and general oven use was obtained from manufacturers. (Note: Ovens should always be preheated before putting glass containers inside. None of the lids are ovensafe. Every product listed special cautions for heating the containers on their labels and websites; we recommend reading these before oven use.) Capacity is reported in cups for comparison. All models were purchased online. They appear in order of preference.
Leaks: We filled the containers with water tinted with blue food coloring and shook them vigorously for 15 seconds and then filled them with moisture-detecting color-changing crystals and submerged them in water for 2 minutes. Containers that didn't leak when shaken and that kept their contents dry when submerged received high marks.
Odors: We refrigerated oil-packed tuna and anchovies in each container overnight and then ran containers through a home dishwasher and checked for odors. Containers that resisted odors and cleaned up more easily were preferred.
Storage and Heating: We filled containers with chili, refrigerated them over a weekend, and reheated them in the microwave, checking for lid warping, stains, and other damage. We also reheated macaroni and cheese casseroles in the oven in the containers.
Containers that didn't leak or spill, held plenty of chili and casserole, and resisted warping, staining, and other damage rated highest.
Durability: We opened and closed each container 100 times, washed the containers 50 times in a home dishwasher, and repeated all the previous tests (leaking, odors, microwaving, opening and closing 100 times). Finally, we checked for stains, warping, breakage, and general wear and tear, giving high marks to those that passed this series of abuse tests in good condition.
Design: We considered features that made the containers easier to use, including simple, intuitive seals and shapes that stack well and make heating and cooling more efficient.