"Opinion's are like (expletive delete), everybody's got one." -Dirty Harry
So here is my opinion on a few core issues as they relate to quilting. If you are old school you may want to look away now, this may cause your eyes to bleed.
I don't do it. I have no desire to do it. I see no purpose it. Back in the day before fabric was printed specifically for quilting and the home craft market, pre-washing was essential for a variety of reasons. In todays market if you are buying quality fabric the technology and methods used to print fabric should be of a quality that prevents the colors from bleeding and running. Batiks are a different story, because the dye process is different you may see some color creep issues if you are not careful, but that still has not convinced me to pre-wash. Maybe I am just lazy.
Let me convert you to my heathen ways with the benefits of not pre-washing. First is body (this could be a man card violation to speak of "body" as it relates to limpness and work-ability in an object such as hair or fabric, not the body of the Russian babe that just proposed to me in my in-box). If you do not prewash your fabric it maintains much of its body, so you won't have to spend an hour pressing and spraying your fabric after you get it out of the dryer to return some of its body. Second is shrinkage (I thought we got all the Cialis jokes out last week). Many people point to shrinkage as a reason to pre-wash but I have turned that around. If you wait until your quilt is completely done, and it was machine quilted, the little bit of shrinkage after the first wash will tighten up the quilting and give your quilt that old school look.
Batik vs. Cotton:
News flash, batik is a cotton, so is flannel. But even if it wasn't what cosmic law says we can't mix fabric in a quilt? Maybe I missed that memo and the quilting Gestapo will have come for me by the time you read this.
An old wives tale tells of threads cutting into fabric. If your thread is cutting your fabric, you have a serious problem with your machine and should seek immediate medical attention. Cheap thread will kill you, or at least frustrate you, (I have seen tears of frustration in a quilting class). Grandma's thread that you inherited needs to be thrown out or put on display, but under no circumstance should it be put in your machine.
Here is some shocking truth, thread color doesn't matter. Most of my quilts have no less than six different colors of threads. I often use leftover bobbins from my long arm for piecing. As long as the tension is set correctly on your machine, no one will know if you used white thread or hot pink. If your thread is showing after piecing and pressing, I can sell you a sewing machine that will make it disappear, or you could adjust your tension.
So there you have it, admittedly I am no expert, but I do have fun. If you are not smiling while quilting you are doing it wrong (that is an expert opinion).