Waterproof breathable rain jackets are not permanently waterproof. Instead they’re coated with a chemical formulation called DWR, which stands for Durable Water Repellant, that causes water to bead up on the jacket surface when it rains and roll off.
The problem is that this DWR coating rubs off after a time, so your jacket soaks up the rain rather than repelling it, making you wet inside your jacket.
When this DWR coating wears out, many people simply buy a new rain jacket. Others try to reproof the DWR coating using aftermarket restorative formulas like Nikwax TX-Direct, Gear-Aid ReviveX or Granger Performance Repel by washing their jackets with it or spraying it on. Unfortunately, these aftermarket treatments work or last as long as a jacket’s original DWR coating.
Have you ever used one of these products to restore the DWR on a waterproof/breathable jacket? How did it work for you?