Exterior Painting: What You Need to Know

A senior man painting a wall with white paint.

I started a successful house painting business in 1970, and it’s still active. So, I have years of experience and knowledge about painting through running this business and undertaking more house painting projects than I can count. This is not a step-by-step instructional article but rather information, tips, and anecdotes from my experience, handed over to you for your next exterior painting DIY project.

Buy Good Brushes

A row of paintbrushes

First, let’s talk about choosing paintbrushes. Do not buy cheap brushes. They won’t do a satisfactory job, and many of these brushes shed bristles into your paint as you work. You have to spend some money on quality tools, and if properly cared for, they’ll last a lifetime. Expect to spend between $12 and $22 for the right brush. Also, don’t buy the angular sash brushes. They’re fine for painting windows, but not for the bulk of the work that you’ll be doing. For latex paints, a synthetic bristle brush should be used; buy at least two, flat head, 2 1/2-inch. China or Chinese bristle brushes are needed if applying oil-based paint.

Use the Right Paint

Next, let’s talk about what type of finish coat to apply. For years, oil-based paint was considered to be the best choice and was thought to hold up well. Over time this has been proven not to be true, and a latex semi-gloss paint has become the pro’s choice.

Before painting, you have to determine which type exists on the surfaces already, whether it’s oil or latex. Moisten a clean rag with denatured alcohol and rub the surface to test. If some rubs off, it’s latex; if not, it’s oil-based. If the existing paint is oil-based, you either have to use the same type of paint over it or seal the surface with an oil-based primer/sealer before you can go over it with latex paint. That’s what I’d do. Latex holds up much better, and clean-up is easy with warm water. It is difficult to clean up brushes used to apply oil-based paint and it requires a lot of paint thinner, which is a hazardous material that is hard to dispose of.

Use disposable brushes to apply your oil-based sealer. They’re very cheap and can just be thrown out in a safe place when you're done. These are also called “chip brushes” or “sealer brushes.”

Don’t Get Ahead of Yourself

Man pressure washing siding

Over my many years as a professional painter, I always power washed any exterior surfaces I was going to paint first, and you should do the same. You want the new coats to adhere to the wall, not to accumulate dust or mildew on the surface. You can find information on power washing here.

Before applying the primer/sealer, finish your power washing and scrape and sand any peeling areas of paint. Wash the house down with a garden hose to remove any sanding dust. Let it dry, and you are ready to apply the sealer.

Caulking is very important as well. All cracks and holes should be sealed with latex caulk, as well as all trim and around window and door frames. I have been complimented on the beauty of my finished paint projects over the years. Customers say my job looks so much better than other painters, and they don’t know why; they just think I am a better painter than most. It’s mainly because I caulk everything. It makes for a special, beautiful finished job.

Get the Mix Right

Now, let’s talk about “boxing” the paint. Regardless if you buy a 5 gallon can, or many 1 gallon cans, you need at least two empty metal gallon cans with lids to use for boxing and as “cut cans.” First, coat the entire inside of the empty cans with an oil-based primer/sealer. Semi-gloss paints will come off of the sides of cans and deposit themselves inside, leaving lumps or flakes behind, so don’t use a paint can that hasn’t been primed with flat, oil-based sealer. If you want to use any old empty semi-gloss cans, soak them in hot water first, and remove all paint to the bare metal surface. Then, seal them just like a new can.

Let the cans dry in the wind and sun until you are sure they are 100 percent dry. Open all your containers of paint and pour them back and forth between their original cans and your two empty cans. This is called boxing the paint. It is necessary because all paint today is tinted and will vary slightly in shade and color from can to can. By boxing, you ensure uniform paint color across your whole job.

Don’t lay your paintbrush across the top of the gallon can. It will drip paint and dry up. Also, don’t dip and then scrape your brush on the open can either. Use a cut can and always put your cut brush directly into the two inches of paint that you keep inside. That keeps your paint clean, your job neat, and your brush free of dried paint.

Pay Attention to the Sun

A house with wood siding has to be painted roughly every five years, and both aluminum and vinyl siding needs to be painted every 15 to 20 years. The sides of the house fade differently from uneven sun exposure, so the surface of the house that receives the most sun will be a different color. Take that into account when you pick your color. I made a killing painting aluminum siding before vinyl siding first came out because the aluminum siding was faded to a different color on every side. I was in business long enough to paint faded vinyl siding too, however.

The sun matters while you’re doing the job, too. It’s tempting to pick a beautiful, sunny day to work outside, but you’re better off with some overcast. Too much sun and heat dries your paint too fast, and you can end up with uneven coverage if you’re not careful. Of course, it can be impossible to find the perfect day. Just remember to work faster in the heat and keep track of how fast the paint is drying behind you.

Make Sure You Clean Up

A wire brush

To clean brushes used in latex-based painting, use plenty of warm water and a wire brush. Make sure to get the paint out of the “heel” or base of the brush. Spin the brush by rapidly rolling it between your hands as you wash.

To store brushes, comb them with the wire brush and place them back in the paper cover they came with. When you’re ready to use one again, take the wire brush to the bristles once more. If you lose the paper cover, wrap the brush in masking tape, but make sure to remove the tape the next day and comb the bristles. This is how a quality brush lasts for years.

As I mentioned before, cleanup with oil-based paint is significantly messier, requiring that you use paint thinner or mineral spirits and wear protective gear. If you do use oil-based paint for whatever reason, be sure you dispose of the paint thinner in a safe place.

Painting is one of those tasks that takes a minute to learn and years to master. No one can just tell you how to cut a good line, how to rescue a drying drip, or how to estimate how much paint you need to cover a stucco wall versus a wood wall of the same size on an 82-degree day with low humidity. These are things you have to develop a feel for. But if you follow my tips and pay attention to the basics, you should be able to do a good job, whether you’re covering one patio wall or painting your whole house.