|I'm using a lot of this stay tape, especially for shoulder seams, when sewing knits.
When I'm ready to sew the tape, I keep forgetting which is the wrong side. I sewed the tape once with the wrong side up and believe me, it's quite itchy next to the skin.
What I do now is brush the sides of the tape, one by one, against my lips. The lips skin is so sensitive that you feel immediately which is the smoother, silkier side.
Hope that helps!