I bought a bunch of basic white Tshirts in a variety of sizes on super sale and have been waiting to embroider them. I have an 'old school' sewing/embroidery machine which did not take kindly to knits. So when I joined the Tech Shop http://www.techshop.ws and saw that they had nice and dedicated embroidery machine, I could hardly wait to get my hands on it.
I decided to use two layers of water soluble stabilizer under the Tshirt. With knits you don't want to use tear away as it can tweak the fabric when it is torn away. Sometimes you use a cut away stabilizer, but since this will go against the skin I opted for a double layer of water soluble to give it heft and then disappear.
I made my color choices (most of them came from the box of thread that the Tech Shop http://www.techshop.ws has on hand - and for no charge)
I chose designs that were preloaded on the machine. let the machine do its thing; rotating the threads as called for. I ran out of bobbin thread and sadly when I picked up the hoop the Tshirt dislodged. I managed to get it back and it is not terribly noticeable. I learned to leave the hoop under the foot; release the anchor snap and just gently slide it out of the way of the bobbin case.
I snipped the threads, and ran the T shirt through the wash - the stabilizer disappeared. The Tshirt is ready to wear.