How to Read Glass Product Marks to Confirm Heat Resistance Grade

For all kinds of kitchen glassware, the bottom marks carry key information about material and heat resistance, which is especially important for judging whether a tempered glass lid is suitable for your daily cooking scenarios. Many home users only pay attention to the size when buying a glass lid, but ignore the product marks, which may lead to misuse of a glass lid beyond its heat resistance limit and cause sudden breakage. Learning to read these marks can quickly confirm the heat resistance grade and avoid safety risks.

First, identify the material mark, which directly determines the basic heat resistance grade. A standard tempered glass lid will be clearly marked with "tempered glass" on the bottom or package, indicating that it has been physically strengthened and can withstand daily high-temperature steaming and regular temperature changes. If the glass lid is marked with "borosilicate glass", it has a higher heat resistance grade and wider temperature difference tolerance, suitable for more intense heating scenarios. Unmarked glass lid usually has no standardized heat resistance treatment and is not recommended for high-temperature cooking.

Second, check the temperature and usage scenario marks. Qualified glass lid will be marked with clear temperature limits, such as maximum heat temperature and applicable temperature difference range. Common marks like "oven safe", "dishwasher safe" and "stovetop not recommended" also define the safe use boundary of the tempered glass lid. For a stainless steel wrapped glass lid, you can find the heat resistance grade mark on the glass edge or the product instruction.

Third, match the certification marks. Food-grade certified glass lid will also carry food contact marks while marking heat resistance, ensuring both temperature safety and food safety. When choosing a tempered glass lid, do not judge heat resistance only by appearance. Always check the official marks to confirm the grade, and use the glass lid within the marked temperature range to extend its service life.