This is a round through tendon about 1″ dia. (it is a dry fit with dowel locking it in place) that I made about 12 years ago. It recently failed. The wood is red oak which is pretty strong, but this area of the peice is very soft, almost spongy. I’m sure a glue repair would never hold since the wood itself seems to have deteriorated. The rest of the peice seems solid at this point.
The question is why did it deterioate? It was always indoors. Is it dry rot? Did I miss something when the lumber was selected and milled or what? Prevention for future failures?
Thanks,
Rooms
Edited 2/21/2007 10:37 am ET by Rooms
Replies
I mention two things, neither of which might be the problem.
1 - it looks like there has been some weathering of the entire piece. If that's the case, then red oak was not a good choice -- it rots faster than many others.
2 - Red oak is probably not as inherently strong as you think it is. When we think of oak being a tremendously strong wood, we are generally thinking of white oak.
Support our Troops. Bring them home. Now. And pray that at least some of the buildings in the green zone have flat roofs, with a stairway.
OK, now we know why homes built in the late 1700's used locust pegs. Just pulling your chain, yesmaam is right, red oak isn't noted for strength, makes pretty furniture, but white oak is used for floors. On the other hand, a peg whittled from locust will last only slightly less time than a rock. It has an even grain and takes stain well.
The two previous replies explain the answer, good old rot. If you want some fun take a piece of red oak, stick it in a pail of water and blow through the end. You will see bubbles. These pathways allow moisture to travel through the piece with incredible efficiency and promote the development of rot.
As to locust, in traditional plank on frame shipbuilding we use locust trunnels (tree nails) as a fastener. No electrolysis issues and as was said before it becomes slightly less hard then stone
Good luck,
Jonathan
Hi all,
Thanks for your input. I also suspected rot, just a bit perplexed since the piece has always been inside since it was made.
Tanks again
Rooms
did you build whatever this piece is green? You have given so little information for anybody to give a very meaningful answer.
It seems obvious that you would have noticed the decay at the time of making, if it had been that decayed.
Is this a plant-stand or something that could have wicked moisture form a pot or something?
I would like to see more photos of the other parts.
There is no such thing as dry-rot. There is a thing called dry rotten wood, but I think that rot only occurs when the wood is in the 30 ~ 40 % MC range.
Kieth,
The piece was built from dry wood, and it has been inside the house ever since. The piece is a historic reproduction of the Glastonbury Chair. The piece that failed is a structural piece at the front of the seat. The 1" tendon was turned on each end of the seat front member. There are the normal forces of the chair on the joint, but It was not abused in any manner (no standing or jumping on it).
While my memory isn't always great (especially several years ago) I hopefully would have noticed rot in the wood when it was made. If there was any rot, I'd sure think that it would have failed sooner than 12 years after making it. I use the chair most every day when I put my shoes on.
Photo of completed piece attached.
Regards,
Rooms
Well, It looks to me that the decay must have been there already, and you just didn't recognize it. Live and learn. The good news, is that it looks like it will be pretty easy to fix with the joinery that you used.It is not totally apparent from your first photo that we are looking at rot, although saying that it is soft sure sounds like it. There are other things that cause wood to be brash, that could cause it to suddenly break. If you take a good sharp blade and cut a nice clean diagonal slice across but more along the grain, it may make it a little more conclusive. Do you know how reaction wood looks? usually it is hard to cut without fuzzing. The first door that I made back in 1969, was from red oak. While moving the rails from one station to another, the bottom rail slipped off of the stack, and a 1/2 x3 x 3" tenon hit the floor first from only about 30" drop. I just couldn't believe it when it broke off clean. Hardness does not always mean strong, it often comes at the expense of brittleness, or low tensile strength.
:
I think you have a stress fracture. Looking at the design of the chair it appears to me that you would put additional shearing forces against that joint anytime you leaned back in that chair and if you brought the front feet off the ground it could be very severe. The wood may seem soft because the fibers have actually been torn apart by the forces applied to it. I doubt you have rot because there is no discoloration of the unstained area of the wood. The little flat spot also concerns me as it may be reducing the load bearing area and concentrating pressure across a smaller part of the pin.
Let me make one more guess. Your right handed.
Allen,
I think you are right. It seems more likely than rot. I just trying to learn through this experience to hopefully prevent future porblems.
Thanks.
Newt:"There is no such thing as dry rot"In england the term refers to a fungus that causes deterioration in wood. It is typically found in older houses requiring all the affected wood to be removed and the area cleaned with a fungicide. It's expensive and cannot be left to spread so it's an important concern to prospective home buyers.When we moved to the US, no one was familiar with the term; I think mold is probably the closest.I apologize if this was more than you wanted know!Cordialy,Hastings
Dry rot is a pretty common term in boat building and repairing.
Rich
Hastings is right Rich. Rot is cause by fungi literally digesting the wood with enzymes it produces. Wood, leather, paper, fabric the thousands of species of fungi don't really care. The mushrooms we eat are the fruiting bodies of those fungi. Four things are necessary for fungi to survive, One oxygen, two right temperature (different species like different temps) , three water and four food (wood in our case). If we keep wood below 15% MC fungi cannot form, most cannot form until 25%, but some species get enough moisture out of the atmosphere to survive on wood. States in the southeast can have wood rot and that has never been outside. In the north our winter furnaces prevent any problems. In the southwest the desert does the trick. In the north west you get rot problems as well. In the boating industry it is not dry rot, just rot from some of the thousands of species of fungi. Sorry as a science teacher I could not resist.
Terry
We're getting into a real semantic issue here. The term "dry rot" is a common term to describe a certain wood destruction caused by a fungus. It's name, "dry rot" may be an incorrect description from a strictly technical standpoint, in that the destruction can not occur in the absence of moisture. But that's not the point. Whoever named it dry rot (long, long ago) had no knowledge of the biology of micro-organisms.
The malady was so-named because the wood looked dry in the area of destruction, vs the kind of rotting destruction in obvious moisture situations, such as a log lying partially in water.
I have repaired many porch railings that were "bone dry," that crumbled to the touch to a dry powder under the (surprisingly) intact paint. Of course, such railings were actually subject to intermittantly dripping water from the improperly configured overhang, which supplied the moisture needed for fungal growth. But the wood was dry most of the time and the problematic water was never noticed.
Hence the commonly applied name, "dry" rot.
Rich
Rich,
I call it dry rot too a lot of times and I 'm a science guy so I guess it is just semantics. Just couldn't keep my mouth shut.
Terry
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