Although this website
https://sawyer.com/products/permethrin-premium-insect-repellent/ says 6 weeks, up to 6 washings or 42 days in the sun, I am wondering if it is 6 weeks from application because once you apply it the chemical will start breaking down and eventually will not work since the 1/2 life is 39 days.
Edit again: Out of curiosity, I started looking around more and can't find a real direct answer on that since one source said if your store the clothes your treated in a bag and with factory treated clothes, it lasts longer. Sorry if I am making you even more confused because now I am.
Edited 2 time(s). Last edit at 06/14/2015 09:35AM by parklover.