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-----Black anodizing after shot blasting is matte
Q. Black anodizing after shot blasting with 0.3mm stainless steel grit doesn't shine; it has an unsightly matte finish. Rubbing with WD-40 makes it shine. What can I do to avoid rubbing with WD-40?
A. Fomenko- Russia
November 10, 2025
A. Hi.
The shot blasting leaves the surface matte, and anodizing doesn't change that. Your choices would seem to be limited to:
• Skipping the shot blasting
• Bright dipping or electropolishing before anodizing
• Applying a clear coat like Everbrite [a finishing.com supporting advertiser] or your WD-40
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to level out the surface.
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Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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Q. Hi Ted. Additional coatings after anodizing are excluded. The surface after shot blasting with glass balls is not matte, it glitters and has a characteristic pattern in the form of a rivet. That's what we need. It seemed to work out a bit, reduced the temperature to 18 °C, reduced the current to 1.5 A/dcm2, the time was 40 minutes. Now it looks shiny, but not completely black.
What else can you do to make it black and shiny?
- Russia
Aluminum How-To
"Chromating - Anodizing - Hardcoating"
by Robert Probert
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A. Hi again.
Your anodizing current density and time sound sufficient for a good saturated black color, but Probert suggests that higher acid concentrations and higher temperatures in the anodizing tank may help get deeper colors. Beyond that, top quality dyes and optimum operating parameters in the dye tank may help.
Sorry, I missed the fact that the shot is stainless steel; if it is producing a characteristic form, maybe we are talking about shot peening more than shot blasting? I don't know if the compressive stress of shot peening slows the anodizing process or the formation of pores, but please advise the thickness of the anodizing and the alloy you are using. If you <send pics for posting> we'll have a clearer understanding of what you mean by "form of a rivet".
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
A. He is imbedding iron particles from the shot, so etch deeper to remove the imbedded iron (meanwhile, wash out the shot).
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
March 23, 2026
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