What's that black wood?
Depends which build you mean.
Molly and I have enjoyed dark wood exteriors on a bunch of projects on our property. We like how it blends into the forest and the shadows created by the canopy overhead and we’ve appreciated how it contrast with a lighter wood interior. Pre-2020, black-ish wood mixed well with the occasional fire scars from 100 years ago. Post-2020 wildfire… it’s in even better company.
Because each build has been an opportunity to experiment, we’ve taken different approaches toward achieving the same black-ish goals. I thought I’d go over them today.
This Cabin was clad in rough-sawn redwood. Molly sprayed down those planks and timbers with a garden pump sprayer that held a mix of water and Ecowood—a solution that’s similar to an iron oxide solution you can make at home with steel wool and vinegar. The Ecowood reacts with the tannins in the redwood, accelerating the visual aging of the wood.
Ecowood’s effect is intensified by the heat of the sun, so Molly laid out the boards on the ground and sprayed them on bright days, rather than our getting mixed results by installing them untreated on the shaded backside of the cabin. I’d also note that while it mimics the aging process, it’s not exactly the same. Redwood tends to go more silver over time and this transformation can be darker, depending on the light it’s viewed in. You’ll also get different results depending on wood species, so, you know, test it first.
Our first outhouse. We used Swedish pine tar on the siding. To apply it you thin it with boiled linseed oil. The application was taxing. Very messy. Thick, tacky, stuff. And required a couple of coats to get an even finish.
Looks great though and if you have wood that’s more rot-prone, this is an effective protectant that’s been in use for thousands of years.
Outhouse 2.0. We wanted a dark color to go over plywood, hemlock, and fir, and were curious to try something more pedestrian. We went with a stain from a local paint shop. Benjamin Moore TimberCoat, semi-solid black. Application was easy, and while I’m sure an experienced pro could make it look better, we found the appearance to be just so-so.
Outdoor shower. We decided to try shou sugi ban. (Or yakisugi, if you prefer.) The Japanese technique of burning wood. Traditionally cedar, but we opted for redwood. We used a propane torch (and some common don’t-set-the-forest-on-fire sense), in charring the wood.
You can leave the surface untouched and it looks very unique, but if folks will be rubbing up against it (as they were in our shower), brushing it and hosing it down is a good idea. We also added some linseed oil atop that, as I recall.
Lastly… not a building, but worth noting, while I’m on the topic. Milk paint. Here it is on a ridiculous stool I made. The stool is terrible… but the paint is delightful. So flat it’s almost chalky. Good for furniture, or wooden spoons. Burnish it with a brown paper bag once it’s dry.
If you’re wondering which we’d vouch for, they have all their merits.
The pine tar is unique in its ability to protect wood and has a depth to its black that I love (as I do with the milk paint). Application is certainly a grade tougher than paint, however. Shou sugi ban probably isn’t worth the effort unless you want to keep the unbrushed charred surface— which is both unique visually, and actually has some protection qualities. I wouldn’t use that outhouse stain again (though I’m mostly not into stains anyway.) Ecowood wins for ease of application and for natural looks, though it doesn’t offer anything in the way of protection, and our appreciation for its effects was specific to redwood. Your milage may vary.