Originally Posted by
Tartan
I use it to get the line straight and then put some pins through it to hold it in place.
I use blue painters tape all the time for diamond cross hatching. I use one strip (approx. 1 3/4" wide) on the 45 degree angle and pin in the middle, before sewing along both sides. Then before removing, use a spacer strip abutting on one side, before removing the first strip and reapplying next to the spacer. Pin, then remove the spacer. This way you can again sew on both sides of the second strip. I save the spacer and use it again and again.