An often oversight for heatsink manufacturers is that they leave the bottom of a heatsink un-finished.  Often times, it is not flat and may actually exhibit areas of roughness.  To fix this, we're going to grab a few sheets of sand paper and start sanding and smoothing out our heatsink surface.  Now most of the time, to accomplish this, you would need to run to the hardware shop and buy a slew of different grit rated pieces.  This can rack up a good chunk of change for just one heatsink.  So last month, David Brown sent me an email telling me he was putting together HSF lapping kits together, asked if I was interested in getting one.  So I thought, why not, lets put something together...

   Included in the kit are 1/4 sheet sections of 600,800,1000,1200,1500 and 2000 sand paper.  The numbers are grit ratings, lower the number, the coarser the paper is.  Also included is 10,000 grit mirror finish polishing compound and an instruction sheet.  There's also another version that includes a piece of glass to use as a flat backing surface.

   For this guide, we'll be using the ThermalTake Spark 7 copper cooler as the test subject.  Before you attempt to do this, you want to thoroughly clean your heatsink and check what temperature your achieving.  Jot this down for later so you can see the difference. 

   Here's the bottom of the unit before the elbow grease work:

   Before working on your own heatsink, remove the fan and other connected pieces on the heatsink.  There will be some metal particles flying around, so try this out in the garage or somewhere that does not have high winds.  The worst is inhaling the dust when you don't need to.

   I found an empty gift box and decided to use that to do the sanding on my kitchen counter (don't have a garage).

   Place the glass piece in the middle and place the 600 grit piece of sandpaper on top of it.  You may want to put a few drops of water between the glass and paper to prevent the paper from shifting a lot during sanding.