I've just read some interesting information, and apparently the first goggles were made of bamboo. I've also found out that whatever the masks were made of, they were hard, as their volume did not change. What I found was a book titled "
Physiology of Breath-hold Diving and the Ama of Japan: Papers," from a symposium held August 31-September 1, 1965 in Washington D.C. It is published under the National Academy of Sciences Library, National Research Council, January 24, 1966. We have access to the entire book at the above link.
In this publication is a paper by Gito Teruoka, titled "Die Ama und Ihre Arbeit," or The Ama and Your Work (probably "their work") and yes, it is in German. There is some discussion of the various types of eye wear used by the Ama, including the mask. The construction of the goggles is covered in detail in this paper, but in German.
From what I can tell, the old masks would have been promptly discarded as uncomfortable as soon as better ones became available. In the 1960s, Japan became a major manufacturer of diving equipment, so the old style masks probably disappeared very quickly.
John
