When enameling with an open bottom (plique ajour), this cloth is used to prevent the enamel from falling out of the setting. After the last layer of enamel, this fiber cloth can be sanded so that a completely transparent bottom remains.
Cut out the required size and use it under your work piece to build up your enamel.
Tip: cut an equally large piece of ceramic paper and place it between your piece of jewelery and the cloth, then no enamel falls through the cloth.