Crack open a fresh walnut to reveal its meat, using a nutcracker.
Rub the meat over the scratch, rubbing in the direction of the wood grain.
Rub the affected area with a clean cloth. Continue rubbing with the walnut and cloth until you see the scratch start to blend in with the rest of the wood. This method works well for light scratches.
Fill in a darker scratch with a crayon that matches the color of the wood and rub with a clean cloth until it blends in with the rest of the wood.
Apply iodine to scratches in mahogany, using a clean cloth. If you have a maple piece of furniture to repair, dilute iodine with household alcohol and cover scratches with the solution.