Not long ago in this column, I shared why it’s so hard to preserve exterior wood using any number of products. One of them was paint. You may have been one of the many readers that reached out to me.

If I had to boil down all the emails I received to just one, it would have read: “Tim, I have to paint my exterior (fill in the blank). I don’t have a choice. Why do paints fail, what can I do to get the longest-lasting result, and what is the best exterior paint in your opinion?”

Hoo boy! Countless professional papers have been written about these topics. Scientists with PhDs in chemistry spend their entire careers wrestling with these questions. That said, I’ll do my best to answer them in the limited space of this column. Let’s get started.

First and foremost, it’s important for you to realize that common exterior house paint is really just glue with color added to it. Think about it. Glue sticks to things, right? That’s what you want: Your paint needs to stick to your house siding, windows, furniture, deck railing and so forth. And, if given the choice, you’d want it to stick for 20 or 30 years!

In my previous column, I wrote that paint and wood don’t play well together because wood has a propensity to expand and contract when it gets wet and then dries. Most paints can’t take this back and forth motion and eventually crack and lose their grip on the wood. Peeling paint is the result.

Have you noticed that you don’t often see paint peel from your car or from aluminum siding or garden tools? The reason is simple. Metal doesn’t expand and contract to the degree wood does. Yes, paint will peel from metal, but the root cause is often based in poor preparation or cheap paint.

Glues work best when they’re applied to clean, dust-free, dry surfaces. The same is true with exterior paint. Let’s exorcise the pressure-wash demon here and now. Pressure washing the object you’re about to paint does not get it perfectly clean.

You can test this with ease. Take your dirty car to a DIY car wash where you can spray it with a pressure washer. Go ahead and use the soap setting, get the wand as close as you feel comfortable to the paint and rinse it. Then pull your car out of the bay and drive to the edge of the lot. Let your car dry in the sun. You’ll see there’s still a light film of dirt on the paint.

To get any exterior object really clean, you need to rub the surface with a sponge or brush using soapy water. You then rinse with clear water. This mechanical agitation gets the object clean just …….

Source: https://www.spokesman.com/stories/2022/aug/27/ask-the-builder-time-tested-exterior-painting-secr/