Three Lessons in Outdoor Wood Finishing

You can make more money finishing outdoor wood if you get these things right.

If you’re a residential painter, chances are good that homeowners ask you to quote on staining their decks, docks, fences and gazebos. But if you’re like many painters, you turn down at least some work in this area because the risks of finish failure are too high. This article shows you three ways to approach taking on more of this type of work.

I’ve been finishing, refinishing, observing and researching outdoor wood finishes for 30 years. I ran my first product performance trial in 1990, and I regularly hear two things from homeowners who come to me for advice. First, they’re often disappointed about how fast their stained outdoor wood starts to look terrible. This is especially true with decks. And second, many homeowners really do dread doing staining work themselves. I hear about it all the time. They don’t have the knowledge, physical stamina, patience nor the prep equipment. Many are looking for capable professional help but can’t find it. To cash in on the demand for this work, you need to learn three lessons.

LESSON #1: Teach Your Customers
Many outdoor wood finishing products are destined to fail as soon as they leave the factory. I know because I’ve tested them and seen them fail even after ideal prep. It’s actually rare to find a transparent or translucent outdoor wood finish that has the potential to endure more than three seasons in full sun. And while this may get you wondering why on earth R&D people in wood finishing labs around the world can’t do any better, outdoor wood finishes have it pretty hard. Sunlight, moisture, temperature swings, foot traffic, mold attack – it all adds up to a very tough assignment. Your job is to know which outdoor wood finishing products can be trusted, to have a realistic understanding of how long different products last, and know how to explain all this to prospective customers so they have reasonable expectations. Customer training is the first and most important part of profitable outdoor wood staining jobs.

LESSON #2: Learn to Prep Quickly and Effectively
Technically speaking, surface preparation is the most important step because it’s key for making outdoor wood finishes last. The goal with surface prep is to maximize the absorption of finishing liquids into wood, especially when you’re using film-forming products. If you don’t prep wood – both new and old – even the best outdoor wood finishing products will fail too soon.

One reason new wood doesn’t absorb finish well is because of something called “mill glaze”. It’s a slightly burnished surface caused by the planing mill that made the lumber smooth after sawing. New pressure treated wood has the additional disadvantage of repelling water. Some brands are actually treated for this, which makes it impossible for finishing products to hang on without prep.

Old, weathered, grey wood, by contrast, is thirsty and absorbent on its own, but the surface fibers are weak and loose. They soak up the finish okay, but they also pull away from the underlying wood too easily over time. So how do you maximize the absorbency and solidity of wood?

A five-year-long field trial held across North America by Akzo Nobel Coatings – the world’s largest finish manufacturer – set out to determine exactly which surface prep technique maximized the all-important absorbency of outdoor wood. In the Akzo Nobel tests, chemical deck washes and dedicated mill-glaze removers were pitted against pressure-washing regimes using plain water and water-plus-cleaning agents. The results of sanding alone were analyzed, too. Bottom-line showed that new wood sanded with a 60- or 80-grit abrasive translated into the greatest absorbency and most durable final finish life of all prep options. Finer abrasives led to poor absorbency. Mill glaze removing chemicals and specialty pre-stain deck washes didn’t measure up to sanding. And while sanding is king in this test by far, the main challenge is how to tackle the job practically over large areas. As it turns out, a two-step process that begins with pressure washing and ends with sanding is the fastest and most effective surface prep approach.

Why begin with pressure washing and end with sanding? Speed. You’ll remove some mill glaze from your wood quickly with the water, as well as sawdust and dirt. Be sure to blast into all nooks and crannies, though keep the wand tip far enough away to avoid tearing up the wood. Let the wood dry for a couple of warm days, then run your sander quickly over the surface to remove fuzz. Fibers like these come off easily after washing with just one or two quick passes of the sander, leaving a very solid and absorbent surface behind. It’s much faster to sand after pressure washing compared with going right to the sanding immediately.

If you’re tackling a big deck, a walk-behind, vibrating floor sander makes quickest work of the job. For corners you can’t beat a 6” random-orbit sander. This hand-held power tool is useful for lots of other sanding jobs, too. Don’t bother with 5” random orbit sanders because they’re too small and weak. A 6” model offers approximately twice the output of a 5” sander. For the tightest nooks and crannies, you’ll love a cordless detail sander. Don’t use the expensive, pre-made sanding triangles, either. Instead, buy a roll of Velcro-covered 80-grit then cut your own triangles. It takes almost no time and saves a bundle.

LESSON #3: Learn Which Products You Can Trust
You can wear out your knees doing all the right prep work, but if you choose a weak finishing product, you’ll get a callback from an unhappy customer. In 1990 I began monitoring samples of outdoor wood finished with the best products of that time, and I’ve been watching new products as they come out ever since. Here are some of my favourites.

Transparent Class: Shortest life, most natural appearance
Olympic Waterproofing Wood Protector Sealant
This stuff is like sunscreen for outdoor wood. It works better than any other clear product I know of, but you can’t expect a long working life. There is no wood finish I’ve found that’s both clear and long-lived. Clients love “the natural look”, but you need to explain to them that maintaining this sort of thing demands a lot of refinishing efforts. Tell your clients they can expect 12 to 18 months (at the most) of good looks before brightening and re-coating is necessary.

Translucent Class: Moderate working life, wood grain shows through colour
Cetol DEK Finish
This film-forming product tints wood, while letting grain show through. It is my go-to option when I want a furniture-grade outdoor wood finish. Applying first coat in “mahogany” and second coat in “cedar” yields a stunning cinnamon-brown shade. Some people love DEK (like me) and other people hate it because it peeled on them once. The difference is almost always surface prep. You’ve simply got to sand before application for reasonable working life with DEK. No sanding means peeling for sure. You can expect 2 to 4 years from DEK before stripping and refinishing is required.

Oil Finish Class: No peeling, but frequent reapplication required
Australian Timber Oil
This is the best performing outdoor oil I know of and it offers three advantages for professionals: it’s easy to apply, it never peels and refinishing requires no sanding. Just clean the surface and apply another coat. Thin enough to be sprayed with even a small sprayer. Outdoor oil or other non-film forming products are the only thing you should apply to wood furniture since peeling is such a hassle to remove.

Opaque Class: Longest lasting of all, but no grain visible
Cabot Solid Color Decking Stain
The oil-based formulation of this film-forming product was legendary, but government regulations mean we can only get acrylic versions now. Still, you can expect 3+ years of great appearance from this product on a deck before stripping and refinishing is required. This product is like paint. No wood grain appearance shows through, which is good for older wood that’s difficult or impossible to brighten.

Superdeck Elastomeric Coating
This is THE stuff for coating ancient wood that’s highly weathered and cracked. It’s thick in consistency, so it has the ability to span gaps and cracks, making old wood look surprisingly younger. It also works well on new wood. The one caution is that wood needs to be completely dry before application. Completely. Even moderate moisture on the wood and Superdeck will peel. This is a relatively new product in my trial line up, but it looks the same today as when I applied it to outdoor wood in May 2015.

One-Time Wood Finish: Easiest but most “casual” looking
Eco Wood Treatment
This is for clients who want no maintenance of their outdoor wood at all, ever, in exchange for a casual look. It’s a powder you mix with water, then apply to wood only once. It imparts an even, weathered grey tone (like barn board) that never fades. Ecowood has recently come out with a coloured version that uses a dye that you mix with the dissolved powder to create a more refined appearance.

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