When it comes to tropical hardwoods, forget everything you thought you knew about deck finishes
Even though my painting company is located in Vermont, we finish, refinish, and maintain a surprising variety of tropical hardwood decking, such as garapa gold, meranti, cambara, and even good old mahogany. They’re all dense, but none are as dense or as durable as my favorite species, ipe; it’s so dense, in fact, that if you throw a piece of it into water, it will sink. Ipe also has a closed grain and is naturally oily, qualities that—along with its density—help make it resistant to insects and rot, but that also make it difficult to finish properly.When it comes to tropical hardwoods, forget everything you thought you knew about deck finishesEven though my painting company is located in Vermont, we finish, refinish, and maintain a surprising variety of tropical hardwood decking, such as garapa gold, meranti, cambara, and even good old mahogany. They’re all dense, but none are as dense or as durable as my favorite species, ipe; it’s so dense, in fact, that if you throw a piece of it into water, it will sink. Ipe also has a closed grain and is naturally oily, qualities that—along with its density—help make it resistant to insects and rot, but that also make it difficult to finish properly.
As my exotic-wood deck finishing and maintenance practice has evolved, I’ve taken on clients from around the country in a consulting capacity. Homeowners and contractors alike often take the same approach to installing and finishing ipe that they would with other species of wood decking, which gets them into trouble. That’s when they contact me. Here’s a sampling of the types of questions we receive and assist folks with.
Coating or Oil?
Q. My contractor finished my new ipe deck with an alkyd translucent exterior stain, and now I have a muddy, dark red stain on my deck, with paintbrush marks, bubbles, and sticky spots. He’s tried twice already to strip the deck back to bare wood, with mixed results, and is going to try again. If he succeeds in fully removing the old finish, what should he use instead?
A. We’ve stripped far too many failing film coatings (like the old Sikkens formulations) from ipe and other tropical hardwoods to think they’re a good idea. Ipe is just too dense and oily to make a good substrate for film-forming finishes, and even has a hard time accepting penetrating oils. Even so, a good penetrating oil with a high trans-oxide pigment content is our preferred ipe finish; we’ve had the best luck with Penofin’s Marine Oil. Armstrong Clark oil-based stains are also very good. Many of our clients have reported success with Ipe Oil, though this isn’t a product we have personal experience with.
Even when the manufacturer recommends two coats, one coat of penetrating oil is plenty for ipe—though you’ll need to follow up with at least an annual maintenance coat. After stripping the old finish from your deck, I would sand the decking with 80-grit paper to improve absorption. The finish should simply be brushed on, then any excess wiped off within 15 to 20 minutes. When you’re refinishing, depending on the length of the deck and the pace at which you work, this may mean brushing three to six courses at a time, and then going back to wipe off excess. Don’t get so far ahead of yourself that you can’t reach back to where you started, because you definitely don’t want to walk on the wet oil.
Fixing Water Spots
Q. I oiled my client’s ipe deck recently with Penofin Marine oil, but unfortunately, unexpected rain showers passed through the area about 12 hours after I finished, and now there are distinct water spots on the deck. Do I need to power-wash the entire deck and start over, or can I just re-oil the boards that are spotted?
A. You should be able to scuff-sand the spotted areas with 80-grit paper and re-apply penetrating oil. Whenever you sand, however, be sure to remove sanding dust from the surface by vacuuming thoroughly or by tack-wiping the area with mineral spirits. Otherwise, the dust will mix with the finish, creating a muddy-looking surface. Finally, wipe off the excess oil within 20 minutes of application.
Sticky Finish
Q. Our contractor applied oil to our ipe decking with a paint roller, then left at the end of the day without wiping off the excess. Now, our deck is tacky, and we haven’t been able to remove the stickiness. Any suggestions?
A. Mix up trisodium phosphate (TSP) with water and scrub the affected areas of the deck using Scotch-Brite pads. Start the mix at 1/4 cup per gallon and adjust if needed. Afterward, rinse the deck thoroughly with clean water and let it dry out for a few days. See how it looks. If there are still some tacky areas, repeat the process. You probably won’t need to re-apply oil, but that will depend on how hard you need to scrub to remove the tackiness.
Removing Rust Stains
Q. We’re installing ipe decking on reverse sleepers over an existing elastomeric deck, and have also been fabricating stainless steel handrails next to the new decking. During our afternoon cleanup, we missed some of the steel residue from the grinding and cutting process that got on the deck, and when we returned the next day the steel dust had reacted with the morning dew, so that the ipe looks like it’s covered with little black dots from a felt-tip pen. What’s the best way to clean up the blackened ipe?
A. Your safest bet would be to sand the decking, then vacuum thoroughly and apply oil immediately. If the deck is large, it might make sense to rent an upright orbital floor sander. When sanding, don’t use anything any finer than 80-grit.
Prep for Prefinishing?
Q. I’m planning on prefinishing my client’s new ipe decking on all four sides prior to installation, per your recommendations. But do I need to wash it first with a product like Penofin’s First Step, which promises to remove mill glaze and “open the pores of the wood” so that the oil finish will be absorbed more readily? And if I prefinish the decking, how long should I wait before installing it?
A. You don’t need (or want) to wash new ipe prior to finishing it. Usually all we do is give it a quick sanding using 80-grit paper, which removes any mill glaze (the soft sheen on the faces of the boards from the cutters of the planer they were passed through) and preps the surface for a finish. We use orbital sanders with very effective dust extraction, so we don’t worry about sanding dust. Otherwise, be sure to vacuum thoroughly, then wipe down the decking with a tack rag soaked with mineral spirits before brushing on the finish. We let the boards sit for about 15 minutes, wipe them down, then flip and repeat the process, making sure to hit both edges too. Then we place the boards on a drying rack, where they can sit for a day or so (depending on temperature and humidity) until they are thoroughly dry. Afterward, be sure to soak the oily rags in a water-filled bucket to avoid the risk of spontaneous combustion.
Fix for Cupped Decking?
Q. My ipe deck was installed just over a year ago, and since the contractor didn’t prefinish the ipe prior to installation, all of the 5/4×6 planks are now cupped. Normally a defective installation would be covered under warranty, but in this case the installer is now out of business. What’s the best way to flatten the boards—remove the decking and reinstall it “cup down”?
A. Instead of flipping the boards (which would be extremely labor-intensive, with no guarantee that they would flatten out), wash the deck thoroughly using a pressure washer and a mild soap such as Cabot Wood Brightener. After allowing plenty of time for the wood to dry out, re-oil the deck and hope it stabilizes. If the cupping is bad enough, you might consider trying to flatten the decking with an upright floor sander, starting with very-low-grit pads and working up to no finer than 80-grit. You won’t need to clean the decking after sanding, as long as you vacuum thoroughly afterward. Unfortunately, there are no guarantees whatsoever when dealing with wood and the elements in a situation like that.
Oil for Ipe Handrails?
Q. My client’s stone patio will have an ipe railing with stainless cable infill. Should penetrating oil be used for the handrails and vertical posts?
A. On handrails and vertical surfaces, I prefer to use a marine-grade spar varnish with a matte finish, such as Pettit Z-Spar Captain’s varnish or Epifanes Wood Finish Matte. Spar varnishes contain UV blockers that help prolong the life of the coating, and while this kind of finish requires more maintenance than a penetrating oil, it will look better and provide a better feel to the hand. We sand the surfaces to 150-grit, then apply about four coats of varnish, scuff-sanding at successively finer grits between coats.
Sealing End-Grain
Q. Do I need to use a special wax sealer to finish the ends of the decking?
A. I suppose that special end-grain waxes and sealers like Anchorseal are effective, but I’m not really a fan. It seems that waxes tend to wick up through the face of the board and leave a distinctive smudge at every butt joint. Instead, I recommend saturating the ends with three or four coats of the oil finish that you’re using for the rest of the board. Each coat will be absorbed quickly, so you don’t need to allow more than a few minutes of drying time between coats. A conscientious carpenter can handle the task right at the chop saw.
Uneven Weathering
Q. I have a customer who has a large covered porch with ipe decking that was installed two years ago. The front steps and first 10 feet go from absolutely no remaining finish and starting to turn gray, to very worn, and then to a spotty finish. The balance of the 30 or so feet of ipe decking is in generally decent shape, with just a few dull spots. How should I approach re-oiling the porch?
A. We see that a lot—different weather exposures on the same deck, especially when the decking is partially or fully covered by a porch. Best practice is to first pressure-wash the entire deck using a mild cleaner, such as Cabot’s Wood Brightener, then rinse thoroughly. With the whole surface wet, you’ll have a pretty good idea of how it will look after the oil is applied, and you’ll be able to determine if sanding will be necessary (to remove graying and make the surface look more uniform) after it dries. In our experience, however, sanding usually isn’t needed, and you’ll be able to proceed with oiling. By the way, this is a good opportunity to talk to your client about a maintenance program (see “Deck Maintenance Programs,” March 2014); it’s usually less costly for the client if you periodically return to freshen up the areas on a deck that you know will weather hardest—the areas that were gray before the deck was washed—than it is to perform the heavier-duty maintenance described above.
Scott Burt owns Topcoat Finishes in Jericho, Vt. He enjoys discussing finishes with contractors at topcoatreview.com, and also hosts ipehelp.com for people with ipe emergencies.