Summary for anodizing removal by bead blast Discussion
Anodizing removal by bead blast is discussed as a local rework problem for improving grounding and bonding on a released product. Paul Stuart asks whether soda blasting or bead blasting can remove anodizing only in a key area, since chemical stripping is messy and not very exact. The reply says that for small local areas, the best approach is often simple wet/dry paper around 400 grit and elbow grease. For spot faces, the answerer recommends making a shaped tool to hold an abrasive disk for a cleaner result, and using masks such as PVC or lead tape to protect adjacent areas. He adds that sodium carbonate blasting is likely too soft, and that alumina may remove type 1 chromic anodize but will struggle with type 2 sulfuric anodize. As another option, he suggests damming the area with modeling clay and using a pipette for a cold strip, with careful flushing afterward.
Q. I am working on the EMI signature of a released product. I have been given a product straight off the manufacturing line and wish to remove the anodizing in a key location to improve the grounding and bonding between parts. Any suggestions regarding this?
I know I can strip the anodizing chemically but that is not a very exacting method. It tends to bleed or splash and otherwise gets messy. Can I soda blast the anodizing off after masking the parts? Or does it require a full bead blast?
Thanks for all help.
Paul Stuart
Mechanical Engineer – San Jose, California, USA
August 20, 2012
A. Hi,
To remove local areas of anodise it is often best to use wet/dry paper about 400 grit and elbow grease.
For spot faces make up a tool (turned bar with dia. to go into hole and shoulder right dia. for spot face) to hold a disk to get a nice result, for squares use a mask like PVC or lead tape to help prevent the wrong areas getting stripped.
My feeling on sodium carbonate is that it will be too soft, alumina will cut type 1 anodize (chromic) but will struggle with type 2 (sulfuric).
The another option requiring an amount of artistic flair is to dam the areas with a modeling clay and pipette
[pipettes on
eBay or
Amazon [affil link]
a cold strip in (take care with this chemistry). The flair comes in getting the chemistry back out (have a wash bottle handy is the secret for hitting any drips and flushing well).
Also the flair is getting the dam to hold – if it leaks have the wash bottle ready to flush the area to prevent damage.
Hope this helps.
Martin Trigg-Hogarth
surface treatment shop – Stroud, Glos, England
November 9, 2012