Whenever I can’t get a stubborn stain out of a linen napkin, tablecloth or a blouse, I do what my Greek great-grandmother did: I squeeze lemon juice onto the stain and put it directly in the sun. When I lived in a south-facing apartment with no outdoor space, I’d open the window and rig ways to hang the stained, lemoned cloth from the window shade so the sun would hit it. Like magic, in a few hours, the stain would be gone!
Recently, when preparing for a photo shoot in Improvised Life’s laboratory, I suddenly realized that the Tyvek shower curtain that had worn to a lovely fabric-like softness had a strange pink mildew creeping up from the bottom…

…as well as a few rust spots from the magnets I’d attached to keep it from billowing.

Neither bleach nor white vinegar put a dent in it. Even its maker, Grain Design, didn’t have any advice for this specific problem, except that Tyvek is an innert plastic that is really difficult to harm, so not to worry too much about what I used on it. “If you come up with a solution, let us know.”
Why not try my great grandmother’s method and squeeze lemons all over the pinkish half and put it in the sun? I wondered. What did have I to lose, after all?
If it worked, I might have the solution to a problem that seems to bother just about everyone: ugly shower curtain mildew.

So I tried it. After I washed the curtain in the washing machine, I cut a lemon in half and squeezed both halves right onto the still damp lower half of the curtain. Then I spread it out on my terrace in direct sunlight, with a rock on it to ensure it didn’t blow away. I rearranged it a couple of times in the course of the afternoon to make sure the affected area was completely exposed to sunlight.

The simple formula of lemon juice and sunlight did the trick and made the shower curtain sparkle again.

…

No sun? Baking soda & peroxide work great!