[Elecraft] K3 metal frame finish

[Ken Kopp]

It looks to me like it's finish was produced by a "vibrating sander"
process.  This method, often used by home-brew'ers, produces a
pleasing finish that doesn't show the scratches sometimes done
during metal fabrication.  The stamped chassis is sanded by an 
orbital sander before going to the metal brake for bending.

Tumbling of metal parts in a mixture of small stones and water
will produce a similar finish.  

A palm-full of wet kitchen scouring powder rubbed on metal 
parts under a dribbling warm water faucet will produce a similar 
finish and is great preparation for priming and/or painting.  BUT,
use caution here ... the aluminum will mark the sink and you risk
your Lady's ire.

73! Ken Kopp - K0PP
k0pp at arrl.net