In line with their inovative approach to instrument design, National invested some research, (probably in conjunction with the Rickenbacher Company), into manufacturing a one piece neck out of Bakelite, one of the first plastics, which had been was developed in 1907–1909 by Belgian chemist Dr. Leo Baekeland. More on the fascinating history of Bakelite can be found at Wikipedia, here.
Sadly despite having a steel rod cast into them as reinforcement, the necks expanded with heat and were not stable enough to stay in tune, so National asked that the instruments be returned to the factory where wooden necks were fitted. The one pictured below was not returned, and still had it's Bakelite neck. The pictures show it in the process of being dismantled by the owner before being fitted with a new National Resophonic neck by Marc Schoenberger.
Most, although not all, Bakelite necks were fitted to Triolian bodies like this one. I have also seen occasional Duolians and style 0 instruments as well.
Note the long slot in the body to fit the neck stick. When instruments were re-necked with a wooden neck it was filled with a metal plate.
The tapped bolt holes into the Bakelite weakened the neck to the point where it frequently snapped at the hole nearest the heel. Please visit the site of Jędrzej Kubiak to see pictures of this and his repair. He also shows clearly the steel rod cast into the neck. Mahalo Jed!
