Anyone with older aluminum siding is well aware of the paint chalking problem. Just rub your hand along the old siding and the chalky old paint will be all over your palm. Trying to get paint to stick to this could be a real problem. This is due to oxidation of the paint. Siding manufacturers originally referred to this problem as a benefit. They called it, self cleaning, as the paint literally washed off the house.
Older vinyl siding is also a problem. UV light fades vinyl siding over time and the siding becomes very unsightly.
Many unfortunate homeowners and contractors have experienced the dismay, when they repainted their homes, only to find the new paint peeling off a few months later. Both problems with older aluminum and vinyl siding can be overcome with proper cleaning, surface preparation and re-painting.
Cleaning ,you will need to rent a powerful pressure washer with at least 3000 psi. You will want a pressure washer powerful enough to remove most of the old chalky paint off the aluminum siding or, to remove any dirt buildup on the old vinyl siding.
Start at the top course of siding and work your way down. You will need to keep the pressure wand fairly close to the siding surface to effectively remove the old paint. In some areas, you may find that the paint comes off to the bare metal. Be careful near windows, corners, soffits and doorways. The water under pressure, can be forced behind these areas causing damage. You can add TSP or other cleaning solutions to the reservoir for mildew, algae or other grime built up. If you do use a cleaning solution, be sure to completely rinse it off with your pressure washer. You should allow your home to dry for several days in dry, sunny weather before proceeding to the painting process.
If you are repainting vinyl siding or vinyl coated aluminum siding, you may need a surface de-glosser. This is a solvent type product used to remove any shine on the surface and to help your first coat to adhere better. You will have no trouble finding a good de-glosser at your local paint supply store.
Application, i like a commercial type airless sprayer. It will draw the paint directly out of your 5 gallon paint pails, through the hose and into your spray gun. These are available to rent at many tool rental locations and even some paint supply stores that supply contractors. If your paint is real high quality latex, it will be thicker than regular latex paint and will require a more powerful airless sprayer.
Priming, this step is equally as critical as the step above. Actually, the cleaning and surface preparation phases will make or break the results of your project.
I like a latex paint additive called emulsa-bond for the first coat. Emulsa-bond is a bonding agent you will add to the first coat of paint or primer, to help it to bond to the old siding.
I buy the best grade exterior latex paint, rather than oil or other solvent based paint. Latex paint seems to keep up with the expansion and contraction of the siding very well. The high quality latex paint I buy needs no primer. I add the bonding agent directly into the first color coat. Check with your paint supplier whether or not to use a primer. The rule of thumb is, when in doubt, use a primer. If you use a primer, add the bonding agent into it before applying. There are also bonding agents available for oil or other solvent based paints. One type is called penetrol. These are usually available at a painting contractor supply store.
Many contractors will spot prime areas, especially where bare metal is exposed. I dont like spot priming because it can lead to an uneven looking top coat. When I put a primer coat on, I prime the entire home. This gives a uniform surface finish later on.
Finish Coat, your top coat will be color only. You should check with your paint manufacturer to see if you need one or two top coats after the base coat. Like I mentioned above, buy the highest quality exterior paint.
In Conclusion, proper cleaning and surface preparation are the two main ingredients to a successful painting job. A bonding agent in the first coat is also very critical to avoid paint peeling off later on. Using these techniques, Ive re-painted homes that have lasted far longer than the original factory applied finish.
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