A pastry cloth is a cloth on which you roll out dough.
Its purpose is to minimize sticking, and allow you to therefore roll the dough thinner. A pastry cloth also allows you to lift fragile pie crusts (such as those made of wholewheat / aka wholemeal) over the pie tin, and invert it.
What makes a pastry cloth non-stick is the flour you sprinkle on it, then rub down into it.
Fans say it’s better than rolling dough on a board, because when you flour a board, the flour just sits on top of the board, and then gets mooshed into the dough as you roll it, whereas with the cloth, the flour goes into the weave of the cloth.
You may wish to mist the work surface with water first (very lightly) to help the cloth stay in place, then put the cloth down. Or, you can first lay down a pastry cloth pad. Or hold it in place with a pastry frame.
If the dough does stick to the cloth, place it, cloth and all, in the freezer for about 20 minutes.
A pastry cloth will be made of heavy cotton fabric, or light canvas. Some are marked with circles of various sizes, to act as guidelines. Most purpose-made commercial pastry cloths have hemmed edges to prevent fraying and tearing. Some people who make their own like to fit them to their rolling boards, and give them elastic hems to hold them on the board.
A pastry cloth is best, some say, if used in combination with a rolling pin sock. Store the sock together with the pastry cloth.
Some pastry cloths may shrink when washed, though some will survive the washing machine still usable. In washing machines, the cloth needs to be washed on a delicate cycle, and air-dried, not put in the dryer. Before it’s completely dry, rub it and tug it a few times to help to stay pliable. Some advise as well, before it’s completely dry, to lay it out flat and pull it out to help it keep its original size.
However, if you bypass washing your pastry cloth, and let stuck-on pastry build up, it can go rancid. So, instead of washing to prevent dough stuck on going rancid, some people store theirs in the freezer in a sealed plastic bag (shake or brush off excess flour first.)