ORIGINAL: flint head
The best I have found is Mean Green window cleaner, It's available at Dollar General stores if you have one in your area.
That's what I bought also. And it cuts the powder fouling like RIGHT NOW! Pretty good stuff and it only costs a buck! I was truly amazed at how fast this stuff works. Get the version with vinegar. At least thats what I bought and was recommended on here. Thanks!
chris