I am making my blocks for the vintage White owners' block exchange. Being a good student, I followed the instructions and bought white muslin at our JoAnn's. I selected the best quality they have. I made 18 blocks but I needed 24 for 2 sets. I ran short with the yard I had purchased because the fabric shifted when I pre-washed it. I went back to buy more but the clerk suggested that the quilter's white broadcloth was a better choice. I purchased enough to complete my last set.
The noticeable difference in the fabric is smoothness. I am not having problems with the Pigma Micron pen bleeding. At first I thought it was the starch that was carrying the ink but now with the starched broadcloth, I know it is the cotton staple that is the culprit. See the bleeding ink in the muslin block on the left, below: