[QUOTE=ManiacQuilter2;6648870 . . . .
When you have the backing clipped or taped to a table, it should NOT be tight like a drum but if you slide your hand over the backing, the fabric should not shift. If the backing is to tight, your top will then be puffy. Are you using enough pins?? I always make sure that there is a pin every 4". That is why spray adhesive is so popular.[/QUOTE]
I "weight" the edges of the backing with curtain rods or yardsticks. I wrap some of the backing that is hanging over the edge of the table around a yard stick and pin it. It gives just enough weight/tension to the backing to keep if from wrinkling/rumpling.