What is this strange ground wire?

[SamWilko]

On my ibanez jem jr, there looks to be a black earth wire that connects from the grounding point on the volume pot into... the wood? What’s the purpose of it?

[galaxiex]

The black "paint" in the cavity is conductive shielding paint.
The purpose is to "ground" the cavity for shielding to abate noise.

[SamWilko]

The black "paint" in the cavity is conductive shielding paint.
The purpose is to "ground" the cavity for shielding to abate noise.

So anything that goes through the shielding paint goes through the output jack?

[galaxiex]

So anything that goes through the shielding paint goes through the output jack?

What do you mean by "goes through"?

Nothing "goes through" it.
It's a shield that is connected to ground.

[vintagekiki]

Conductive shielding paint is for preventing (RFI) radio-frequency interference (similar as Faraday cage)

https://en.wikipedia.org/wiki/Electromagnetic_interference

[Fluoroscope 5000]

It might be going to the trem claw.