What bag should I use for cooking pot-stewed vegetables?

Go to the drugstore to buy a mask. After disassembling, sew more threads with a sewing machine according to the required size to make a bag that can hold all kinds of spices (aniseed). The mouth of the bag must be tied tightly with cotton thread or something. Because the mask is pure cotton gauze, it will not release harmful substances when it is made at high temperature, and it will not melt and be damaged due to high temperature. It can be used repeatedly after cleaning. Therefore, it has always been the first choice for soup, medicine, fashion medicine and all kinds of stewed dishes.