Kauai is famous for its bright red dirt. Red dirt shirts are sold all over the island. We saw them on sale 2 for $38. Last time we were here we made some ourselves, but they were pale compared to the commercially produced ones and I came to the sour grapes conclusion that they had thrown in red dye.
We decided to try it again this time. It is fun even if it doesn't work! We collected dirt from the Spouting Horn parking lot.

In with the dirt.
In with the shirts.

We soaked them for 24 hours and then dried them out. Dry they looked like the shirt on the left. Like red dirt on top of a white shirt. Once again, it wasn't working.

Google to the rescue. It turns out you've got to set the stain with vinegar. Hey, sour grapes were just what we needed after all. After soaking them in white wine vinegar water they look like the shirt on the right.