I'm adding larger
HSF to the chipset on the EVGA 780i and in doing so came up with an idea ( I'm sure it's not original ) that will aid in lapping heatsinks-especially aluminum base ones. The picure shows different states of anodized aluminum and that is what gave me the idea to put a very light coat of paint on it for the initial sanding. As you can see, the anodizing makes it simple to tell if you have it flat, and these certainly were not.
I would suggest making the paint very thin-even see through, or it will clog your sand paper.