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Ted Mooney, P.E. RET
Pine Beach, NJ

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Etching aluminum with a matte surface

2003

Dear sir or lady:

Please let me know what is the formula to reach a satin finish for aluminum parts? I have been trying caustic soda ⇦liquid caustic soda in bulk on Amazon [affil link] etchant according to this formulation: 50% NaOH 4% sodium gluconate 1% sodium sulfide 25% TEA(triethanolamine) 0.1% ammonium persulphate reminder water but the final appearance is not what I need, I need a opaque and uniform surface aluminum profile after etching process.

If any one can help me I would appreciate very much! "thanks a lot"

Setareh Saeidy
- Isfahan, Isfahan, Iran

Try ammonium bi-fluoride at 1/2 to 1 oz per gal room temp after a good cleaner

Drew Nosti, CEF
Anodize USA

Ladson, South Carolina

2003

You may try the following formulation and operation parameters:

Free NaOH = 50 g/l
Aluminum content = 28 g/l (with caustic soda ⇦liquid caustic soda in bulk on Amazon [affil link] recovery system) or 130 g/l with long life additives
(mainly sodium gluconate)
Temperature = 50 - 55 °C
Etching time = 10 - 13 minute

What aluminum alloy you are referring to, 6063. 6061 ...

THANK YOU,

EDDY
- Selangor, Malaysia

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