[CR]Anodized Finishes

(Example: Framebuilders:Alberto Masi)

Date: Tue, 18 Feb 2003 09:14:48 -0800 (PST)
From: "Dale B. Phelps" <losgatos@ix.netcom.com>
To: classicrendezvous@bikelist.org
Subject: [CR]Anodized Finishes

Anodizing is a treatment which is intended to seal the surface of the material treated. The value of a sealer is generally to reduce the propagation of corrosion, though there are recognized incidental benefits of certain TYPES of anodic finish. Basically There are three types of anodize finish - as determined by the end effect on the surface of the material. Interestingly, these are referred to as Types 1, 2, and 3. As I recall, Type 1 is very much a superficial rinse and surface seal, usually cosmetic and traditionally was clear but often with colors. Types 2 and 3 are considered progressively "hard" finishes, much more durable and having a hardening effect on deeper base metal. 2 is usually black, and 3 is greenish or greyish-black. 2 is opaque, 3 can appear somewhat translucent.

If need be I can pull out my Machineries Handbook (recommended reference book for ALL listers) to look it up, and if REALLY need be I can pull out the ASTM or ASME or whatever tech spec governs these sorts of things, but the above outlines the basics of anodizing as a surface treatment. In most cases for bike components then, I'd see any ano finish as corrosion-inhibiting and/or cosmetic. Hardening of chainrings, etc would come from heat treat of the machined parts prior to/post finishing.

This is an interesting thread of discussion, much more so than the glut of e-bay-related blather that seems to consume 90% of each digest-condensed message I receive! Hopefully my contribution to the discussion will be helpful.

Dale B. Phelps
Los Gatos California