Please help blue heatsink stains after lapping. HELP URGENTLY NEEDED!

[technobot]

How do I get rid of these blue stains on my heatsink after lapping? They appeared after I let the heatsink dry.
Isopropyl rubbing alcohol) doesn't remove them.

 

[technobot]

ANYBODY...

 

[JofaMang]

A metal polish would probably work, but I am not aware of the risks that might pose to your system if exposed to even just polish residue.

Copper "rust" is blue. If you can re-lap just enough to remove the blue stains, don't let it dry, instead use alcohol immediately after lapping to remove water from the surface. This may reduce the moisture levels on the surface, and prevent it from happening again.

Maybe, just throwing it out there.

 

[technobot]

OK, if anybody else ever has this problem I have found the solution...

It's Ketchup, I rubbed a bit on the heatsink and it instantly removed the black marks!

Thank you JofaMang for your response.

 

[welshmousepk]

im assuming thats because of the vinegar content?

in which case, vinegar would be the answer?

i really dont see how you came to the conclusion of trying ketchup though...

 

[aberchonbie]

i think the blue is caused by oxidation.. likely that the micro scratches exposed the copper to a bit too much O2.. that's my guess..

the watercooling community know that ketchup will do wonders on copper surfaces.. glad you found teh solution