Originally Posted by
Stanley Covington
True. There has been a lot of materials science research in Japan, and I read some papers on it when I was a student. Kigoroshi does not greatly decrease the strength of softwoods, within limits of course, but the cells of hardwoods are irrecoverably weakened. Don't recall the percentages, but it was significant. Sorry, but I don't have copies of the papers anymore, and yes, they were in Japanese.
Another very astute observation was made by Mr. Waldron. Kigoroshi is not usually combined with heat or steam, just water. In carpentry work, in my experience, they don't even use water. With time and weather changes, the pine or cedar will swell naturally. Not sure if oak would....
Perhaps I lack in skills, but the idea of cutting a door, furniture or casework joint and then trying to "lock" it using kigoroshi and moisture is mildly repulsive to me now. The very idea of pounding a shoji joint home with a hammer is shocking.
If I cut a M&T joint, and glue it, the tight fit will wipe all but a fine film of the glue off the tenon when inserted. The glue alone will lock it so tightly that the joint would be destroyed before it could be disassembled. I am sure your joints are the same way.
I don't mean to offend those that see Mr. Odate as a saint of Japanese woodworking, but I will share a story of an embarrassing incident for me. I read the article in FW by Mr. Odate about making shoji a long time ago when FW was still black and white and Mr.Odate was a spry artist. He instructed that the narrow sides (vs wider cheeks) of mortises should be sloped inwards towards the bottom (making the mortise narrower/tighter at its bottom) so that the rail's tenons are compressed when hammered home. He also advocated using rice paste as a glue because the joints could be disassembled later.
I made quite a few shoji for homes and restaurants in Las Vegas and Salt Lake city using these techniques, and they worked OK, but they had problems. I went back to Japan again soon after, and showed my new master, Mr. Honda, a renowned joiner, Mr. Odate's techniques. The old boy looked at me in deep disgust like I had cockroaches scrambling in an out of my facial orifices.
Mr. Odate's technique is a version of kigoroshi. It messes up the tolerances and precise positioning of the rails. Precision is critical in shoji and other such joinery work. Mr. Honda made it clear that kigoroshi is not a sound technique where precision is required with slender parts. I had experienced the difficulties Mr. Honda mentioned, and so could only agree as I turned red with embarrassment.
But, silly boy that I was, I did try to argue about the rice glue. It makes sense, right? This time, he gave me a sad face as his rheumy old eyes followed the cockroaches, and said: "Why would you ever want to take a rail/stile joint apart, Stan?" You need the glue to keep the joint tight over the shoji's 70 year lifespan. Rice glue is weak. Kigoroshi tenons will loosen over time and with stress. "Try hard not to be a fool, and maybe you'll average out as just an idiot," he concluded. Wise words. SHMBO insists they didn't take root in my case.
Kumiko joints are not glued with anything, and can be repaired when they break. But rail/stiles joints are forever.
Stan