Sewing tip

Made a new quilted post card today. Haven't gotten it photographed yet so it is not listed yet at my etsy web site http://www.sewupscale.etsy.com but wanted to share this tip with any who sew. I used a knit top my granddaughter had outgrown. It had horses on it. Since it is a little difficult to sew knit fabric without it stretching, I used iron on interfacing to the back. Worked great. Very little stretching.