Many car parts, paintball marker components and other aluminium items are anodised. Anodising creates a protective oxide coating on aluminium objects, preventing corrosion and strengthening the surface. Anodising can also be used to create a durable coloured layer on the surface of a piece of aluminium. Over time, anodised finishes can fade. They may also develop scratches and nicks. In these cases, it may be best to remove the old finish so that you can re-anodise the piece.
Clean the aluminium part thoroughly. Remove all dirt, grease and other contaminants with soap and water or a commercial cleaner. If the part is not clean, you may not be able to evenly strip the anodised surface.
Place the part in a nonreactive container, such as a disposable plastic bucket or glass baking tray. Do not use metal containers, which may react with the stripping agent.
Apply stripping agent. Spray the part evenly with oven cleaner, making sure all surfaces are covered, or combine water and household lye until the colour on the parts lightens. You may see dye seeping away from the aluminium. Always add lye to water, not water to lye.
Wait for the finish to dissolve. If using oven cleaner, wait three minutes, then rinse the parts thoroughly, scrubbing with an old toothbrush. If using lye, wait approximately 10 to 15 minutes, depending on the strength of the solution, then rinse the part in vinegar and scrub it. If any anodised finish remains, repeat the stripping process. Don't leave the stripping agent on too long, or you may pit the surface of the aluminium.
Rinse all parts in clean water. If the surface of the metal has become blackened from the stripping agent, polish it with a mild abrasive cleaner and a toothbrush. You may use the deanodized parts as-is, or re-anodise them.
Very strong solvents may damage the aluminium. Always wear eye protection and gloves when handling caustic chemicals or acids. Work in a ventilated area.