I tried Michael's way where you throw a thick cylinder. You make it just like you would when you are first throwing your pot but before you start shaping add the second clay. This is done by taking a loop tool and cutting vertical grooves into the cylinder. You'll likely want to cut these groves the same distance apart all around the piece but it might be interesting to try just doing them on one side. After the grooves are cut you push coils of the different colored clay into them. I used Highwater's Phoenix and Orangestone clays because they are very different colors, I like them both in atmospheric firings, they have the same shrink rate, and I had them on hand. I'm sure you could do the same thing by wedging mason stains into your clay body. I might be inclined to use a really white clay for that but, again, it might be interesting in a colored clay too.
Once you're done pushing the coils into the cylinder you can finish throwing the pot. Yes, it might not feel like a perfectly smooth surface but if you just work with it and control it as much as you can it will be fine. You may have some unevenness at the top, just cut it off with your needle tool and compress the rim.
I'm glad this pitcher made it through the firing. It was in the front row at the top so it got a nice glaze from the ash. The only other glaze on it is a shino liner.
Check out the gallery page - Future Relics Gallery by Lori Buff