coffeebreak

I keep hearing not to pre wash pre cuts like cake layers and charms...but never "why?". I mean, I always pre wash my yardage...100% cotton shrinks no matter the settings. I always wash on mild, low heat etc. but there is still shrinkage as I can tell when I fold the fabric ..it isn't square as it was on the bolt..but adjust to cut and it is fine. I figure that is the same with pre cuts...but still..if you don't wash them...the fabric will shrink once in the quilt. I have heard it said that that has never been a problem for some..but that doesn't make sense..not saying anyone's lieing..just trying to figure it out. If something shrinks after washing it alone, why wouldn't it shrink if it was attached to something else on a first wash? Does it have anything to do with the manufacture? Moda says not to pre wash, but the ones I buy at Joann's (I can't afford the BIG name brands very often!) I did try to not wash it first and it messed up when I did wash the finished product.

So how can some cotton shrink and other cottons don't..I know the quality of the cotton can be at issue and the "better" cottons might not as much as the cheaper ones..but still...please share comments and experience! Thanks