I finally figured out what was causing my ink + trans beads to develop a purple cast: Premo Frost! I've used it in the past with ill-effects, so I'm not sure why it turned rogue on me. Oh well...
So, I tried the same beads with regular Premo Trans. No evil color cast! Yay! But I was tired of the whole issue and when the beads finished baking, I just left them in my toaster oven and went to bed. This was unusual for me, since one of my favorite parts of working with trans is taking the red hot beads out of the oven and tossing them into ice water. In the morning I checked out the beads to make sure they were truly purple-free (yes!) and noticed every single bead had mini fissures running their length (they're elongated ovals). Great, I thought. Trade in one problem for another.
Then I remembered I hadn't ice-water-bathed them. Also, in the back of my mind, I remembered reading something about the ice water helping "heal" small cracks.
So, I put those bad boys back in the oven and brought them up to curing temp. Then I took them out and threw them in ice water. Ta-da! The cracks healed. To be sure, if you look really close, you can see where they were, except the surface is smooth and unbroken. I think they cracked along ink layers between the trans. I might mix things a little differently in the future.
Yay for ice water!