Painting vinyl or another metal material other than aluminum will be greatly different, so it's important to be sure of what you're about to paint.  Galvanized steel should not be painted with oil-based paint. Many paint manufacturers offer multi-purpose enamel or a direct to metal paint. Determine if the siding has been previously painted and what kind of paint has been used. If possible, bring a sample to a professional. Aluminum can be difficult to tell apart from vinyl if brand new. Check for cracks or dings in the siding. If the siding is cracked or broken, it is vinyl. Dings or bumps are an indication of aluminum.   Try tapping on the siding because aluminum sounds hollow and lightly metallic.   Use a magnet to determine if your siding is steel versus aluminum because magnet will stick to an steel siding but not aluminum. steel will also show red-brown rust. It's best to use a power washer, angling the spray in the direction rain would hit the house as washing from the bottom up can cause unnecessary damage to the siding.  If you choose to use any chemicals, complete a final rinse to remove remaining materials because residual chemicals can be damaging to your painting process.  If you've got stubborn stains, try cleaning with a biodegradable laundry detergent by mixing approximately ¼ cup (60 milliliters) detergent with 4 gallons (16 litres) of water.  Rub your hand along the siding when it is dry to check for chalking, which is common. If a powdery substance comes off, don't be alarmed because this is chalking, which is normal in paint made for aluminum substances. This powdery substance acts as a self-cleaner for the siding. Simply choose a detergent containing TSP (trisodium phosphate) to remove the chalking.  Repair any damaged siding by banging out any dents or sags or removing unsalvageable pieces altogether. Depending on how big the area is that you want to paint, you may want to use a power sander. Always start with a rough sandpaper and finish with a fine. Make sure to avoid etches and special molding, so that you don't damage them. Give your siding a sweep afterwards, from the top down, to ensure you've removed all the metal filings and any chipped paint.  Use rough sandpaper (80 grit) to start your sanding. Do a rough once over while making sure to keep your motion in the same direction. Move up to a more fine sandpaper (220 grit) and do a second pass over the siding. If you want to use a power sander, be cautious when applying pressure to prevent any damage to the siding. Don't use less than 80 grit sandpaper as it can cause permanent damage to the metal.
تأكد من أنك تتعامل مع الألومنيوم. نظف الغطاء. قم بسنفرة الغطاء.