An Interesting Cottonwood Burl
About a third of my bowl sales are commissioned by customers and never appear on the Bowls for Sale pages of my web site, so this blog gives me an opportunity to show some of this work. Typically a customer provides the log or burl from a special tree they recently lost. This is a great way to preserve a piece of a tree that had become a special friend to the family. I recently received a large cottonwood burl from a 150 year old tree that came down in Nebraska. The burl was freshly cut which is good. I prefer to turn green wood since the turning is easier and there is less dust. If you ever turned an old dry burl, you know exactly what I mean. The following two images are of the burl which was about 18 x 12 inches in size.
The burl had a large decayed out area that presented an unusual challenge, especially since the burl was oval in shape and a lathe will carve a round shape. My plan was to place the base or foot of the bowl on the bark top of the burl, carve the profile from the base toward the wider top, paying attention not to penetrate the decayed inner area, and flair the cut outward near the flat part to keep a bark edge. I mounted the burl on my lathe using a board (screwed to the burl) to attach the burl to the lathe. The live center tail stock kept the burl tightly attached and the 3.5" Elio drive in the head stock permitted the burl to be manipulated to a good position. Pictures are worth a thousand words.
A 4.2" diameter tenon was turned into the base of the bowl first and then the carving of the outer profile proceeded.
The above image shows the complete outer profile which is flaired out at the top. There is already nice grain figuring showing up (colored patterns from spalting and some flame in the lighter areas). The next images show the reverse mounted burl and the hollowing process. I used a Oneway stronghold chuck with number 3 jaws to reverse mount the burl. I kept the tenon as large as possible to give the chuck a good stable grip. This tenon will be turned off the bowl after the drying process.
Note that part of the bowl's outer side has some bark. I like this natural look and also was concerned about carving through the side wall into the decayed void.
Above it the top view ready for hollowing. The hollowing went slowly and I used a 1/4" gouge to do most of it. This small gouge cut the best through the punky decayed areas. The next image shows the completed top view of the bowl. There is a lot of very nice spalting in the bottom and sides, with some flame figuring in the lighter areas (flame or curl does not show well in unfinished wood). The dimensions of the completed bowl are 17 x 11 x 5.5" with a 0.5 " wall thickness. This wall thickness was chosen to best show the bark edge and to minimize problems turning a bowl with so much decay.
The next images show different views of the completed bowl, which will be drying for several months before sanding and oiling. I will add images of the finished bowl when it is complete.
The following images are of the finished cottonwood burl bowl, sanded, oiled, and waxed.