Black stain spreading on keris during vinegar cleaning

[A. G. Maisey]

Nitric acid is faster Marco.

But jokes aside, citric acid works well, I've used that too, and a lot of people in Indonesia currently use citric. In fact anything acidic will clean a blade, its just that I prefer vinegar because it is cheap, easy, consistent.

But if I could still get decent pineapple juice, I'd still be using that.