One place near me when I lived in TN would finish cleaning with water- not sure that is the best way. The local shop here will do a final de-greasing immediately before they hang it in the oven. We take parts fully cleaned, sometimes bead blasted if that is needed. It's tough to never touch a part or get it dirty between our place and his, so he goes over it one last time.
Regardless, I would make sure the acid is neutralized with a base (like baking soda) solution or similar before powder coating. Then rinse well with clean water to remove the acid, base or salts left behind by the acid-base neutralization process, which makes salt and water. Any acid (or base or salt) remaining in the nooks and crannies, even as mild as vinegar, will keep aciting if it's trapped under the powder. Heat won't neutralize any of it. It will only drive off the water and leave the undesirable molecules behind to keep wrecking your parts.
1967 Galaxie 500 Red original Q code 428
1967 Galaxie 500 White with Black stripes 428PI clone- car is dead & long gone, sold near Oak Ridge TN 2000, would love to find it.....
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