In a bucket, soak pumice stones in a mixture of potassium permanganate and water for approximately 30 minutes. The longer you leave the stones in the mixture, the more dramatic the effect will be on your clothes.
Turn off the water supply to your washing machine via the shut-off valves.
Place the pumice stones in your washing machine with the jeans, and run the washer without water for approximately 20 minutes. Check the jeans after 10 minutes to see how they look. If they are left in too long, they could be ruined.
Remove the jeans from the washing machine and inspect them. If you like the way they look, move to the next step. If you desire more of an acid-washed effect, place them back in the washing machine and continue washing with the pumice stones. Check the jeans every 10 minutes until you reach your desired effect.
Remove the pumice stones from the washing machine. Turn on the water to the machine, and wash the jeans as you normally would.
Dry the acid-washed jeans in a dryer.