whats the best way to clean soot off horns?

i got these horns and they had so much soot on them it took me and my buddy a few hours to get the bells clean, now the manifold has some in the air line ports and the corners of it. any advice?

Have a read of this here…
http://www.hornwhistleboard.com/viewtopic.php?f=2&t=6493

I used paint thinner and a metal brush for all 5 horns and manifold it took about 10-12 over a week mine were bad they are early 1980’s so they have been around awhile I also painted them flat black when I was done to make them look new