The most important indicator for measuring the quality of a thermos is undoubtedly the insulation effect. It can be seen from national standards that products with larger capacity, smaller bottle mouth, and inner stopper have better insulation effect. The national standard requires that insulation cups should indicate their insulation effectiveness on the product packaging for consumers to refer to and compare.
Of course, you can also test the insulation performance of the insulated cup yourself. You can pour hot water into the thermos at night and come the next morning to check if the water in the thermos is still warm. If you find the first verification method too slow, you can also directly pour hot water into the thermos, let it sit for two to three minutes, and touch the bottom of the bottle with your hand. If there is temperature at the bottom of the bottle, it indicates that the vacuum part in the middle of the thermos has failed and the insulation effect is not very good.
