It is almost impossible to wash them, as then you have all sizes. I do not wash before sewing. I sew my project, then I buy a nice piece of clear plastic (the little heavier kind) and put it over my beautiful table cloth. If I use place mats to match they go under the plastic also. No muss no fuss. Just wipe clean after your meal. Hope this helps you, it has been a Blessing to me. And saved many a beautiful items.
Have a Blessed day
Ellen