Cleaning copper channels?
 

Once i've soldered my blocks they gain this lovely coating of.. whatever it is.. which can't be good for performance. Is there any substance/liquid which can clean this stuff up without breaching the integrity of the solder joint?

They got some stuff that cleans copper. I think it is for antiques.

http://www.rb-treasures.com/MPI_Prod...rassClean.html

http://www.steelglo.com/default.asp?p=inside

It may help in determining what you are talking about if you could post a pic of 2.

It could be a few things, and cant really suggest anything other than what Jaydee suggested without knowing what it looks like

posting pictures is a toughy, no camera.. but if you've ever plumbed in solder copper pipes you'll know what i mean, the pipes discolour rapidly at the high heat, picking up a black tarnish.

I wanna clean out the insides of the channels on this thing, it looks like that Arrow stuff Jaydee posted would be ideal (can't reach the inside to scrub it). Was also thinking about boiling it in vinegar, read that someplace on a cookware cleaning tip site :P