I completely agree with Iceblossom. The only time I use the cutting mat lines is for a quick rough measurement. And there is no reason why you have to use only one side of the cutting mat. Just like fabric, you bought both sides so go ahead and use them. I have 1 old mat that I use if I have to cut batting. Batting fuzz is really hard to get out of/off a mat. I have tried many different things and find a plain white pencil eraser works the best.