Before washing, I reread the original blog instructions. The author indicated she'd had less luck with Sharpies, which we used, than with other permanent markers. There were also several comments from readers who said that nearly all the color, except for the marker dots, had washed out. Not wanting sad kids, in an abundance of caution, I:
1. ironed the shirt
2. put it through two High cycles in the dryer; then
3. washed it on Gentle in cold.
I don't know if that was overkill, but the color stayed fairly well, and the small people are happy. Therefore, I am happy.
[Please pardon the poor quality iPhone photo. The camera was packed for a trip, and once something is packed it does not come out until we reach our destination. And, until the next iteration of the iPhone is released, I'm trudging along with my trusty 3G. Poor, poor pitiful me.]