It is seldom used for marking, but it is better to use a pencil that is easy to remove.
On your desktop, when you bought a mat, you drew a grid on the new mat yourself. When writing, you can see the clear grid through the paper. Just pay a little attention.
People who have been writing for a long time already have their own writing habits and don't need grids at all.
If it is a crease, you need to finish your work.
1. Hang it with clips or fix it on the wall with thumbtacks for a long time.
2. Spray water on the crease of the work with a watering can (master the skills and scope, otherwise it will easily destroy the work), and then put it in a dry place to dry and save.
If you can't wipe the rest of the grid yourself, please handle it with a professional mounter.