My process for cleaning chains is a little different, but if you really want it clean, this is the way.

I got an ultrasonic cleaner typically used for cleaning electronic parts from a friend for free. They're not too expensive new. I put the chain(s) and cassette in the parts cleaner. Fill until parts are covered with Simple Green. Use the 35 minute timer and let it do it's job. This truely gets the chain amazingly clean with little more work than removing the parts. One problem with all 'green' cleaners is they leave an organic residue. I dunk the parts in a jar of toluene and then dry them to remove any residue. Toluene has a higher flash point so it's a lot safer than gasolene and I think even mineral spirits.

You can get an ultrasonic cleaner on ebay for about as much as one of those silly chain cleaning kits and it will do a much better job with far less work.