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Thread 485/91

Sticky finish on hard coated part

Hey everyone, My company recently sent out a part to be re-anodized. The part originally was hard anodized black. We performed some machining operations on this part and then requested it be stripped of any existing anodize and re-hardcoated. The part we got back has a very matte finish that is somewhat sticky to the touch. It almost feels like it was spray painted. BTW, the material is K100-S cast aluminum plate. What has happened here?

Jason Silverman
Engineer - New Britain, Connecticut, USA
April 18, 2008
publicly reply to Jason Silverman

Jason

A sticky feel to anodize is an indicator that the anodize might not be sealed. Typically, hard (black)anodize is not sealed unless requested.

Willie Alexander
- Colorado Springs, Colorado
April 25, 2008
publicly reply to Willie Alexander

Sticky acetates from the dye and residue from the seal is bleeding out from the casting porosity. Do some hot/cold/hot/cold rising after the seal and clean-up the seal.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

April 25, 2008
publicly reply to Robert H Probert

May 2, 2008

Unless you requested a seal it should not have one and would feel "tacky" to the touch. The dull appearance is normal from stripping.
Do not wash the part until you contact your vendor and confirm whether or not he sealed the part or you may inadvertently wash the color out.

Bill Grayson
- San Jose, California, USA
publicly reply to Bill Grayson

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