#eggshells

#eggshells

But once food has carbonized and bonded to metal, the issue is mechanical, and you need something to physically break the residue apart. Eggshells are mostly composed of calcium carbonate, the same mineral found in chalk and limestone - you've probably encountered it in your toothpaste, too. When crushed into a powder, these shells become a mild abrasive, which can gently sand down the grime.