Copper Coating Item or Drop

A item that can be used to coat 8 pieces or maybe blocks of copper like a dye in a crafting table.

It is a clear coating that stops the copper from aging.

The coated copper blocks could look the same or have a very small difference.

The item could be gotten as a mob drop, such as a secondary drop from the glow squid. For the glow squid it could be what coats the glowing spots so the glow is still visible. So it makes sense why it would drop it sometimes.