At the moment’s automobiles use extra aluminum of their bodywork than ever earlier than. And whereas far fewer basic vehicles have aluminum our bodies, the query nonetheless comes up incessantly: how do you paint aluminum? Whether or not you’re restoring an early Shelby Cobra or just respraying a workaday classic Land Rover, it’s an excellent query. As a result of aluminum is such a unique materials than metal, a layer of thriller appears to hover over its restore course of. In fact, portray aluminum isn’t vastly totally different, though there are some particular concerns.
Aluminum’s Distinctive Properties
Refinishing aluminum presents a number of distinctive challenges in comparison with metal. Notably, aluminum naturally types a skinny oxide layer when uncovered to air. This may restrict the power of paints and primers to stick. This layer should be eliminated by means of correct cleansing and preparation to make sure dependable bonding.
Nonetheless, sanding could be more difficult attributable to aluminum’s softer nature, which may gaul and fill sandpaper. To stop contamination from different metals, any instruments or abrasive surfaces (sandpaper, scuff discs) should be devoted to aluminum. It may possibly additionally corrode when uncovered to moisture, particularly when involved with dissimilar metals. If moisture will get trapped between the aluminum and paint or filler, it could result in corrosion and harm.
Aluminum additionally has a better coefficient of thermal enlargement in comparison with metal, which means it expands and contracts extra with temperature adjustments. This may result in points equivalent to cracking within the paint or physique filler if not accounted for.
Lastly, aluminum requires an etching primer (ideally epoxy primer) to chunk by means of any remaining oxide layer. The identical goes for physique filler if when making use of immediately to reveal aluminum.
Portray Aluminum Bodywork
Making ready and portray aluminum bodywork requires cautious steps to make sure correct adhesion and a easy end. Right here’s an in depth information:
Collect Provides – For instruments, an orbital sander, sandpaper (grit 80 to 400), scuff pads, spray gun or paint sprayer, paint mixing cups, masking tape, masking paper, respirator masks, and security glasses. For supplies, an aluminum cleaner/degreaser, etching primer, high-build primer, base coat, clear coat, and paint thinner or reducer.
Clear the Floor – Use a degreaser or aluminum cleaner to totally clear the floor. Take away any grease, dust, or contaminants.
Sand the Aluminum – Begin with 80-grit sandpaper to take away the manufacturing unit end and roughen the floor. Sand till the steel is uninteresting. Transfer to 220-grit, and end with 400-grit to attain a easy floor.
Take away Mud – Use a clear material or tack material to wipe away all mud and particles from sanding.
Apply Etching Primer – Use an etching primer particularly accepted for aluminum. This promotes higher adhesion. Spray or brush the primer evenly and permit it to dry in accordance with the producer’s directions.
Sand the Primer – As soon as the primer is dry, frivolously sand it with 400-grit sandpaper to create a easy floor. Wipe away mud afterward.
Apply Physique Filler or Excessive-Construct Primer (elective) – Fill small imperfections equivalent to sanding marks with a high-build polyester primer. If the floor is already easy, you may skip this step. Conversely, deeper harm equivalent to door dings could require a skinny layer of physique filler first.
Most common polyester physique fillers will work high quality over epoxy primer for gentle harm. If the world is deeper, a short-strand glass-reinforced filler will present higher energy. Permit every layer to treatment in accordance with product directions, then sand it right down to a easy end with 400-grit paper. An aluminum-filled physique filler is NOT required., nonetheless.
(Alternatively, you may additionally apply accepted direct-to-metal physique filler to scrub naked aluminum earlier than primer. The aluminum floor be clear and dry when doing so to stop trapping moisture. This might trigger poor adhesion and the filler may doubtlessly draw back from the repaired space. Fashionable epoxy primers usually bond higher with naked aluminum, forming a corrosion-proof barrier for filler to stay to.)
Paint Utility – When portray aluminum with a base/clear paint system, combine the bottom coat paint in accordance with the producer’s directions. Apply a number of skinny coats, permitting enough drying time between coats. As soon as the bottom coat is dry, apply a transparent coat for cover and shine. Once more, use skinny coats for a smoother end. In the event you’re utilizing a single-stage paint system, merely apply your colour in skinny coats and permit to treatment. Relying on atmospheric situations and whether or not you’re utilizing heay lamps or an oven, curing could take a number of days. Learn the instructions in your paint materials earlier than you begin portray.
Reduce, Buff, and Polish – After curing, you may de-nib any dust or runs within the paint as you’ll another end. You too can color-sand and polish the clear coat for extra shine utilizing a sharpening compound. Rigorously take away all masking tape and paper; verify for any overspray and clear it up as wanted.
