Last spring, I participated in a pinwheel block exchange. We were instructed to starch our fabrics before we constructed our blocks. I followed the instructions but had a nagging feeling that starch may prevent the ink from penetrating the fibers of the fabric. Today, I ran a little test. I starched one sample twice with spray starch and pressed it flat. The other was pressed and signed. On each sample I used the same 4 pens, a Sakura Pigma Micron Pen, an Identi-pen, an Uni-ball Signo (a water resistant ink for check signing), and a Zig Ball Pen. After writing, I heat set the ink for 10 plus seconds and then ran the sample under hot running water in a strainer basket but used no laundry products.
As you can see, the starch does keep the ink from penetrating the fibers deeply. The Micron Pen and the Identi-pen did the best in the test so far. Now, I wonder what laundry products will do to the samples.