EditorAnne asked the following question in the comments for the Printing on Fabric - Printing 2 lesson:
Even though I always peel my backing off the fabric along the straight grain, the way you do, I find that the minute I place the fabric in the water, the piece distorts diagonally. I'm careful not to tug or wring it, but it happens anyway. It doesn't seem to matter what type of printer fabric I use. (I do prefer EQ Printables, though, like you.) I can't get the bias distortion out, not even by pressing it "persuasively" (as Ricky would say) with steam afterwards. Does this ever happen to you? What could be causing it? How can I prevent it?
I thought I'd answer Anne's question here since I'm sure many of you will run into this.
The skewing happens when the grain of the fabric is not square on the backing paper. Take a good look at your fabric sheet before you print on it. If you see the grain of the fabric running at an angle to the edges of the backing, you will find that the fabric skews as soon as it hits the water in the rinse step. The worse the angle, the more skewing will occur. For example, if you follow one horizontal thread near the top of the sheet of fabric and find that on the left side it's 1/4" from the top of the sheet but on the right side it's 1/2" from the top, then the fabric will skew 1/4" once it hits the water. I've found that I can work pretty easily with a 1/4" skew, but when it gets to be 1/2", then it's a bit more challenging (and frustrating)!
I have to say, I've had much better luck with EQ Printables than other fabric in this regard, but I've trained myself to always "analyze" my fabric sheets before printing. If I find a fabric sheet that looks bad, I place it in a separate stack for "test prints" and don't use it in my final project.
I have found that I can still work with slightly distorted images by pressing/steaming the heck out of it and hoping that the other fabric I sew it together with will keep it in shape. As a last resort, I "quilt it out".
The only way I know of to completely prevent the skewing is to treat your own fabric with Bubble Jet Set, because then you have complete control over how the fabric is placed on the freezer paper. I usually tear the fabric along the grain a little larger than sheet size to ensure that the fabric is square to the grain, treat the fabric with BJS, then iron onto freezer paper (also a little larger than needed) and finally trim to size. That said, I'm usually doing things at the last minute and don't have time for that whole process (and I've had good luck with the EQ Printables.)
Hope this helps. And if you have any other questions regarding this, feel free to ask!