On Fri, 05 Jun 2009 10:33:56 -0400, HK wrote:

You can find it very difficult to measure the hardness of very thin
coatings, but titanium nitride is estimated at Rockwell C 85. It is
coated on to drill bits, steel knife cutting edges, and the titanium
handles on my Buck folding knife. It is yellow in color, and is used
for decoration as well as wear resistance. You can color anodize
aluminum that color, but I don't believe the coating is as abrasion
resistant as the nitride, notwithstanding the fact the all aluminum
has a coating of sapphire, transparent aluminum oxide.

Casady


Interestingly, the gold-tone coating on the spools of my Penn spinning
reels does not seem to wear off nearly as easily as the coating on the
Shimanos. It's strictly ornamental, though. Both brands of reels work
well for me...

The simple explanation is that one is anodized and one is nitrided.

Casady