At long last I finally called Coppertone and inquired about sunblock stains on my clothing. (other company's sunblock has also stained my clothing ... FYI) The Customer Service gal on the line didn't hesitate (like she gets this question all of the time) and explained that the stains are due to avobenzone in the sunblock. As the entry in Wikipedia explained, Avobenzone reacts with minerals to form colored complexes. So if you have hard water (a lot of minerals in your water) commonly caused by having well water, the iron in the water binds to the avobenzone and creates stains in your clothing. Coppertone recommends applying the standard stain removers before washing your clothing, which I have found to be almost completely ineffective. Mainly (as I explained to the woman) because the stains show up after I wash the clothes. Which stands to reason if it's binding to the iron in my water! (Unless of course I'd been mining for iron in my back yard with sunblock on, in which case the stains would show up before I washed them. Eeegads.) To that, the kind Coppertone Woman explained that a lot of people say that the stains show up afterwards (oh boy) and then recommended using Rit Rust Remover or Iron-Out. I looked that stuff up and basically these have strong acids that can irritate the skin if not completely rinsed out of your clothing. One site recommended using detergent with phosphates in it against rust stains! Terrific. How about putting something in our sunblock that doesn't hurt us or our clothing? Afterwards I read that lemon juice can be effective against rust stains in the laundry. Stay Tuned. I'll try it.