Start: Use hook 3 mm and chain 64. Start in 2nd stitch from how at each row.
ROW 1+ (1 single crochet in back loop only) 62 times, 1 single crochet in both loops, 1 ch, turn.
Repeat until you have a square cloth. I make 60 rows to get a square cloth.
Tighten the last chain, so that it locks, cut the yarn and weave in the end.
Babaaaaa: You now have a cloth, that is ready to use 🙂
FYI: The last single crochet, that you crochet as a normal single crochet stitch, makes the cloth more firm on the edge. If you also make it in the back loop, it will be somewhat uneven to look at.