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topic 14483

Masking hard anodized part

A discussion started in 2002 but continuing through 2018


Q. We have two stamped Aluminum parts(90 mm x 70 mm) that we are hard anodizing in a custom color. We need to make electrical contact in two areas. The contact pad size is 2 mm in dia. Is it possible to Alodine then mask the contact areas and then hard anodize? What is this going to do to cost? Would it be easier/cheaper to Alodine the inside surface and hard anodize the exterior surface? Are there other was to have electrical contact on a hard anodized part with out the aluminum oxidizing?

Don Porter
- Sunnyvale, California, USA

simultaneous 2002

Don't forget the principle of anodizing (chromic or Type II) as a maskant for hard coat. Anodize in Chromic, grind off where you want to hard coat, then grind off where the chromic was left on.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
Editor's note: Mr. Probert is the author of Aluminum How-To / Aluminio El Como
and co-author of The Sulfamate Nickel How-To Guide


There are Electroless Nickel Baths available that plate a deposit 60 RC+ hardness. Electroless Nickel is electrically conductive has the same hardness as hardcoat and much better lubricity and frictional properties. Electroless nickel is usually more expensive than hardcoat. If you are going to have to do two different coating process with anodise and Alodine then electroless nickel may be very cost competitive. Also if you are coloring the hardcoat it is not as hard as it could be.

Todd Osmolski
- Charlotte, North Carolina, USA


Hi Don,

Yes! "Alodining", masking and Hard anodizing is routinely performed. Conversion coating the substrate not only provides excellent adhesion of the masking but is also a good corrosion inhibitor.

Bill Grayson
- Santa Cruz, California, USA

October 6, 2011 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

I have a component that needs Type II (SAA) anodizing & Nickel acetate sealing for certain area and the remaining area must be Type III (hard) anodized.

I need masking material for both the processes and Process sequence (Which anodizing must be processed first?).

James Martin Samson

Hot glue for masking type III anodize

November 24, 2018

Q. Wondering if anybody has tried hot glue for type III anodize? If so, what were the results and what kind of glue was used?

Isaac Kissinger
Masker - Philadelphia, Pennsylvania

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