WSO insert soaked for 2 - 3 minutes.
Gen insert soaked for 4 - 5 minutes.
I've posted this technique in another post asking why bleach is not doing the job in fading inserts. In my opinion, bleach is not a strong enough agent to do the job. If it's working for you, the insert is not of a very high quality.
I've gotten lots of question about how to use the Drano. Any drain cleaning product containing lye (sodium hydroxide) will work.
I use straight drano in a small glass bowl. Please be very careful. The stuff is very caustic. It can blind you! I recommend using rubber gloves and eye protection. A small amount is a glass bowl is not going to asphyxiate anyone. You can safely do this indoors.
Put the insert in the drano and stir it around for 30 seconds or so. Take it out, rinse with water, dry off (you wont see how well it's faded when wet) and check the color. Redo the process until you are happy with the amount of fade. It will take anywhere from a minute to five minutes, depending on the quality of the insert.
WARNING: Remove the plastic pearl before you start. The Drano will dissolve it. YOU HAVE BEEN WARNED!
Good luck.
Marty