Today we are going in to a fairly simple process called lapping. Lapping is the process of making a heat sink perfectly flat. We want the metal to metal contact between the heat sink and CPU die and chip to become one. The more contact both have, the better thermal transfer. Nothing is flat, and lapping is one of the solutions we have to achieve better results. However, lapping doesn’t fully make everything better. That’s where thermal compounds come into play. They will fill in the microscopic valleys of the two metals. By lapping you are reducing the size of the microscopic valleys thus making the thermal compound and metals work more efficiently. Lately the heat sinks are coming the factory flatter and better machined then ever before but there is still room for improvement. This is where lapping comes in. Typically you can lose between 2-10 F by lapping. First off you need a perfectly smooth surface I use a piece of tempered glass from an old refrigerator but for safety reasons you could also use Plexiglas. Also keep in mind here I mostly use Thermaktake or Zalman heat sinks, which are pretty flat right from the start or to the eye anyway. Start off with 800 Grit wet dry sandpaper or emery paper sand off any high spots until sink looks evenly scratched in one direction. Than I usually go to 1000 grit then for my finish I use 2000 grit. Most of these sandpapers and the 2000 especially can only be found at auto body supply shops. You can get a mirror finish off the 2000 grit paper and I recommend using water so also make sure its wet dry paper. For the ultimate finish do not use anything that contains any wax it will affect thermal conductivity. What I use is made by 3M it is called Imperial Machine Glaze. 5 minutes of light rubbing will give you the equivalent of a copper mirror. Here is a picture of the final product notice the camera in background I could not take a picture with flash due to the mirror finish made the picture all white. The sink shown is a Thermaktake Volcano 11+.