The horn itself is pewter. I’m assuming you have one of the PYO-horn PYO unicorn. If the paint is already flaking off, I’d first remove it, then prime it, then paint it.
I’m not sure what I would use to remove the paint – simply a stiff old toothbrush to begin, then q-tip dipped in acetone or the likes if push comes to shove.
To prime the horns, I use a spray-on sealant.
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