🟡 mediumwhat am-i

What is black when you buy it, red when you use it, and gray when you throw it away?

Common Wrong Answers

Coal

Coal is black when mined, but it does not turn red when used; it burns but does not produce a red color like charcoal does.

Firewood

Firewood is typically brown or tan when purchased and does not turn red; it burns but its color does not match the riddle's description.

Bricks

Bricks are usually red or brown when purchased and do not change to gray when used; they do not burn or turn color during a typical use.