I did not work for me. 
Maybe I did it to long.
Instructions I found on the web after I did it.
Firstly you need to boil some water and make sure it is boiling hot.
Remove the rubber from the case and put in the boiling water for about 30sec – 1 min.
Remove the rubber from the boiling hot water and put on ice cold water for about 10-20 sec.
Dry the silicone case with paper towel or cloth and then I hope it will be good as new.
Post time: Jun-28-2017