Crucibles, used to determine constant weight, are constructed from materials with high temperature resistance, including porcelain, glass, quartz, nickel and platinum. Crucibles are manufactured in high-form and low-form shapes, as well as in multiple sizes. Crucibles may come with a loose-fitting lid that allows gases to escape during sample heating. Crucibles with fritted discs are also available, which eliminate the need for filtering paper and allows for the drying of precipitates.