I gave them a dunk in some very diluted Jacquard Fire Red dye and then piled them up on trays that I could microwave. The Mister's love of Chinese food keeps us well stocked in these plastic containers. I used the lids.
The dyeing worked very well but I still have no idea if they are actually clean enough to spin. The sun has to do its job for a few days before I'll know if all this work was worth it.