How to Prepare to Paint Metal Siding

What You'll Need
Trisodium phosphate (TSP)
Small bucket
Garden hose
Spray nozzle attachment, medium setting
Stiff bristle brush, long-handled
Paint scrapper
Putty knife
Vinyl exterior spackle
Electric sander
Primer for metal
100-grit sandpaper
Paint thinner
Wooden stick
Clean rag
Safety goggles
Rubber gloves
Dust mask

If you have to paint metal siding, it is vital that you prepare the siding properly. This will facilitate proper adherence of both the primer and paint. Once your siding begins to peel or look dull, it is a good time to repaint it. Successful application of paint on siding gives your home a facelift. It also enhances the aesthetic appeal of your home. It may take some time and effort as you prepare to paint, but the results are well worth it. Below is a guide that will help you prepare adequately.

Step 1 – Wash the Siding

A thorough washing helps clear dirt and grime from your siding. Prepare a solution of TSP and water that is adequate for the area of your siding. It is best to wear safety goggles and rubber gloves to protect yourself from the cleaning solution. You may also want to wear a dust mask to prevent inhalation of loose paint and dirt. Dip the brush into the TSP solution and scrub down the siding from one end to the other.

Step 2 – Rinse

Use plenty of water from your garden hose to rinse the siding. It helps if you attach a spray nozzle with a medium pressure setting to clear away dirt and soap.

Step 3 – Scrape off Paint

It is likely that your siding had a previous coat of paint. This has to come off, as much as possible. Use a paint scraper to clear away loose paint. You may want to use an electric sander if your siding covers an extensive area.

Step 4 – Brush

Use your stiff bristle brush to clear the loose paint and debris from the siding.

Step 5 – Repairs

Carefully inspect the entire surface of the siding for damaged areas. You may spot some small holes that need to be attended to before you paint. It is best to fill such holes with a vinyl exterior spackle. Apply a small amount of spackle to the hole and fill it in securely with a putty knife. Allow 1 to 2 hours for the spackle to dry completely.

Step 6 – Sanding

Use 100-grit sandpaper to sand the dried spackle. Sand until you achieve a smooth surface and the spackle is flush with the siding. Use a damp cloth to clear dirt from the area. You want to be certain that you apply primer onto a clean surface.

Step 7 – Apply Primer

It is a good idea to thin the primer before application. This helps it to penetrate more effectively into the siding, especially if you had a previous coat of paint. Mix 1 pint of paint thinner and 1 gallon of primer in a small bucket. Use a wooden stick to stir continuously until you get a uniform appearance. Apply a thin coat of primer over the siding with a paintbrush or nap roller. Once it has dried, you may want to apply a second coat. Allow the coat to dry completely in preparation for paint.