Mirror shine possible when lapping aluminium?

C

cheezies

[H]ard|Gawd
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Feb 8, 2003
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Is it possible to obtain a mirror shine when lapping an aluminium heatsink? I've only seen mirror shines on copper from the guides and posts I've read. Any advice or suggestions on how this could be possible?
 
cheezies said:
I've heard that using compound worsens thermal transfer, is this what your are suggesting?
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Probably. Compound indeed does hinder thermal transfer because it is not thermally conductive.

Back to your original question, in theory it is possible to give aluminum a mirror finish if you sand it smooth enough. I would expect that you could get similar results compared to copper using the same method, so you could give it a shot if you're so inclined.
 
Believe me, I wasn't suggesting actually putting any shine compound on your heatsink. I was saying it would be the last thing you'd want to do on such a surface. Like I and the other guy said, I think very very fine grit sandpaper is your best bet. If you've already lapped it to some degree, I'd say start from about 1000 and work up to 1500, 2000, etc. Then maybe rub it down with some alcohol and see how reflective it is.
 
Mothers Mag Polish or even Brasso lots of products out there to polish alum. - auto parts stores wal-mart etc. Clean well with lint free cloth (coffee filter) and alcohol when done.

I have found a mirror finish to be of no benefit but it will not hurt anything either unless you polish so much to take it out of flat from the lapping. The polish should just be a 2 minute "clean up" after the final sanding, if not then you need another round of sanding with finer grit paper before attempting to polish. It is of even less benefit if you do not lapp and polish the IHS to match. Then if you are really into it, you put a dab of polish between the IHS and the heatsink and lapp them to each other,
 
Aluminum shines up nicely. 2000-2500 grit finish sanding and a chunk of Neverdull wadding polish does the trick. As other have said though a shiney surface doesn't provide better cooling. Best to just sand it flat and leave it at that.
 
Thanks for the suggestions. I was hoping that thermal paste stuck on a mirror shine would be easier to clean than a dull surface. I just purchased a lapping kit from easypckits.com and I'll see how it goes.
 
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