Sanding Oxidized Copper Blocks

Implement a crafting recipe with eight copper blocks of the same oxide level and one sand block.  This 'sanding' would reduce the oxide level by one.  This would allow players to leave out a field of the blocks to fully oxidize and then consume sand to revert them to the desired level, at which point they could then be waxed to prevent further oxidation.

This could be better for performance than requiring each copper block to check its surroundings unlike in the other suggestions that propose copper oxidizing at different rates based on environmental conditions.