I've been making quilts for many, many years- I have never pre-washed a batting- to me that seems like a lot of work when it's easy enough to just buy a batting that does not shrink more than I would want. as for- pre-washed vs. not.... many things determine how much a quilt will shrink when it is laundered- the fabrics, that batting, the density of the quilting, how it is laundered all play a role. I've made many quilts that had both pre-washed and unwashed fabrics in them- I've never had one come out (horribly wrinkled). even quilts that contain flannels and regular cottons together have come out just fine. if you make an all cotton quilt- use an heirloom type cotton batting (that says to quilt it every 2") and you launder it in warm water & tumble dry it- it will (crinkle- look like an old, antique quilt) people who make that style of quilt & use that type of batting generally do it because that is the look they want. batting packages tell you how much shrinkage you can expect- also the density of quilting the batting requires. if you make your quilt, have it quilted to the minimum recommended density- launder it gently on cool & tumble dry it on low heat it won't shrink much at all. generally I pre-wash if I have a bleeder- other than that I don't always worry about it (I pre-wash if a fabric smells funky, feels funky or has saturated color that wants to bleed) I mix batiks with flannels, and lots of other combinations- and I choose the batting with the properties I want. my favorite is Wool batting & it does not shrink as much as cotton. browse the pictures category here- you will find lots of quilts that have both washed & not- (my backyard gathering quilt is wool applique on black flannel- nothing was pre-washed- beyond the wools being felted; the flannel background was not pre-washed- in the pictures it has been laundered a couple times-- my Connecticut quilts are all regular cottons- nothing pre-washed except the reds used in the appliques the quilts have been laundered in the pictures- after completion.