And now it seems, 5 years on, another update is in order. As I explained at the time of making the trellis, these garden structures, while ostensibly for containing dirt and supporting climbing plants, are really a laboratory of sorts for me, to get a chance to observe how certain woods and certain kinds of joints do over time in the harsh conditions of the outdoors. Save for exposed end grain, none of the wood is painted or 'sealed' or has any finish other than what my plane leaves behind.
I am convinced that the hand planed finish does the best outdoors and all other attempts to apply coatings are simply doing nothing to make the wood last longer and just giving you a new bit of maintenance work to do, so I don't bother. Planed is best, though I will note that the Black locust boards were not hand planed, but just machine planed, IIRC.
First up is an overview pic, showing all the structures in the garden:
As you may note, if you looked over the previous build threads, the black locust garden beds are now elevated, while they were, prior to this year, sitting right in the dirt. The reason for this is largely to combat Meadow Voles, which are now well established in the community garden and which caused a couple of my beds last year to really underperform. I'm not a care and share sort of fellow when it comes to rodents. So, this spring, I dug all the dirt out of the beds, re-leveled the ground, laid down some galvanized hardware cloth with a 1/2" mesh, then placed a perimeter of CMU's, aka cinder blocks, around the edge, and then placed the wooden beds back on.
This should keep the voles out, and as a benefit the beds have twice as much soil and require less stooping to tend. It also allowed me to see the condition of the black locust a little more clearly.
This picture shows what might be a typical condition:
The black locust was purchased green, the only option in N. America it seems, and has undergone a fair amount of distortion, cracking and movement over the years. This was to be expected - the multiple through-tenons though have held on quite well, which is good to see.
Black locust is famed as an extremely durable wood in contact with the soil, with people stating that fenceposts can go 50 years in the ground, and so forth, but I am a bit underwhelmed so far. One bed in particular is undergoing significant degrade and rot:
The diagonally-opposite corner of the same bed also shows that it is rotting away, much faster than anticipated:
That's a big disappointment. The other two locust beds aren't nearly as bad, but they are still more deteriorated than I would have expected. Still, the locust, at $4.50/bd.ft., was cheaper than most other options in rot-resistant species, but still, I'm not sure I will be inclined to use it again, unless I could find it properly dried. Hah, good luck with that.
The Jatobá trellis, on the other hand, shows zero signs of rotting, and is holding together well, though the wood movement of this species overall is a bit on the high side it seems to me:
The Jatobá does not accept/retain end grain paint well, and does not degrade with much in the way of end-grain checking, so I guess in future I could skip the paint step with that material.
Next is the Spanish cedar pyramidal trellis with teak cross pieces fastened with stainless screws:
That's doing really well, with no appreciable degrade save for the usual weathering to silvery grey.
The last one to look at is the newest bed, completed in the past couple of weeks in my spare time:
I've noticed that different woods have different abilities to retain end grain paint, with Jatobá being noticeably poor in this respect, and Honduras mahogany the most excellent. The new bed is made from teak, which is oily and difficult to glue, but which should last very well outdoors. I used a special epoxy for oily woods and sealed the end grain with that, then applied a clear coat epoxy with white pigment over that. It will be interesting to see how well it holds up over the years.
The corner joints are a place where various joinery options present themselves. I was briefly tempted to do a double-mitered half lap, but that joint, it seems to me, has certain vulnerabilities, so I went with triple rod tenons and 6 shachi-sen fasteners, making the corner joint using a separate nose piece:
I think this should hold together well, but we'll see of course.
A view of a different corner:
A little gappy on that upper rod mortise, but I made these joints at a high rate of speed, and not the normal care I would take with furniture or architectural joinery. Nothing to see here folks, just move on....
The other outdoor wood/joinery experiment I have going on is the shrine lantern in my front yard, which is of Honduran mahogany and currently looks a bit forlorn:
There is a landscape maintenance crew which looks after the front yards in our community and last year a less-than-attentive mower operator, no longer with the company, caught the corner of the roof of the lantern head and tore it partially off, creating quite a bit of damage. I took the lantern head off last fall and brought it to my shop but I just haven't had the time to deal with it yet. I need to make a new roof altogether.
I noticed of late that the support framing for the head was also damaged, so I have to take another layer off yet and fix a couple of sticks:
Hoping to get to that work before the summer is gone. Sigh! Otherwise, the mahogany is clearly the champion in terms of withstanding the elements.