I've soaked Hoover cloth bags in a Woolite solution or very mild soap. I think I used just a tad of Persil laundry soap last time I washed one, but it was a very minute amount. I didn't soak it long either. I also tried not to have the area with lettering immersed long. I think I mostly bobbed it up and down in solution, let a soak a couple minutes, do some more bobbing then let it rinse and lay flat to dry.