aluminum etch without HF

I'm trying to etch 3003-h18 aluminum layers without using an HF solution. The problem I've been having is severe pitting without any
grain boundary information. Is there a milder etch that takes more time? I am new to aluminum so any help would be great. Grain sizes range from pancaked ~30 micron in bulk to ~5 micron equiaxed at interface. Most of the literature does ebsd, but alas I don't have an sem handy.
Thanks, -srvclapton
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srvclapton wrote:

NaOH dilution (something like 10-40 %), preferably heated to 60 degC should work.
Jukka
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