<Begin Segment 2>

MN: Now going back to Mr., I guess you said Homer Kimura?

GK: Kimura, yes. He designed a type of mill, Jordan type paper mill, and he designed it, the plans were sent to a company in Los Angeles and sent to the machinist in Los Angeles where the company made the machine, sent it back up, and it turns out that this milling machine was really critical in extracting a much purer rubber. And in addition to the increased purity of rubber, they were able to separate the fiber from the rubber, and it made it possible for them to make a rubber that had a greater tensile strength than even tree rubber. That was a remarkable accomplishment.

[Interruption]

GK: What you do is you get a uniform size strand of rubber, and you pull it, and you find out how many pounds per square inch it pulls before it breaks, so that's the breaking strength. Hevea rubber breaks at about 3,800 pounds per square inch. Salinas guayule rubber breaks at about 3,800 pounds per square inch. Hevea rubber, tree rubber, is a higher quality, and breaks down about 4,200 pounds per square inch.

[Interruption]

GK: Okay, the purification of the rubber after the extraction with the Jordan mill, the purification was done chemically using techniques developed by Shimpe Nishimura and Frank Hirosawa, and they both have some background in rubber chemistry. Frank Hirosawa was actually a rubber chemist and Shimpe Nishimura was a nuclear physicist, he helped build the cyclotron at UC Berkeley. That was before he got interested in plants. But anyway, so the combination of Homer Kimura's Jordan-type paper mill, and the chemical extraction process developed by Shimpe Nishimura and Frank Hirosawa, they were able to come with a rubber that had a tensile strength of over five thousand pounds per square inch, which was significantly stronger than even Hevea rubber. So the Manzanar project was very successful as far as developing a rubber that even probably to this day has not been matched. There is a company today that makes a high-quality guayule rubber. It is used primarily for medicinal purposes because it is hypo-allergenic, and compared to Hevea rubber, which about ten percent of Americans are allergic to it. So hypo-allergenic rubber is possible with guayule because guayule rubber does not have the allergens that is contained in the tree rubber.

MN: Now your father mentioned that they had the Manzanar guayule rubber tested outside. Can you share a little bit more of where this rubber got tested?

GK: These rubber tests, the tensile strength measurements that I gave you, tests were done in an independent laboratory in Los Angeles. It was either called the Kirkhill laboratory or Kirkland laboratory or something like that. It's a rubber company, and they make rubber, so they're the ones who tested the rubber. And they said that this was some of the highest quality rubber they had ever seen. So that was a nice compliment to the project at that time. And also it was the highest quality natural rubber that they had ever seen, which was comparable even to the tree rubber.

MN: Other than Manzanar, I understand Poston also had this project going. Do you know how it went at Poston?

GK: They had some, I know they didn't do much of the chemistry there. They probably grew some of the plants, but I'm not very familiar with the work there.

MN: Do you know why today we don't use guayule rubber a lot more? Is it just that, you mentioned earlier, the Hevea rubber plant is -- I guess I don't remember --

GK: Hevea rubber?

MN: Is that easier just to get rubber out of?

GK: Yeah, it's easier to buy it than grow it yourself, as long as it's available. Now, one of the problems with Southeast Asian Hevea tree rubber is that pretty soon with the growing populations, people are going to want to grow food instead of rubber. So there is a lot of pressure on the lands where the tree rubber is growing, and some of these tree rubber plantations will be probably be cut down in order to grow food. But it's difficult to say, because right now they're making some money by selling the crop to the industrialized countries, and these countries are also industrializing themselves. So there will always be a need for natural rubber. Petroleum based synthetic rubbers cannot replace natural rubber at the present time.

MN: Why not?

GK: Well, the tensile strength, it doesn't have the tensile strength or elasticity or heat tolerance that natural rubber has at the present time. It's possible to, it might be possible to develop synthetic rubbers that do have those qualities, but at the time, probably... if they can't make these improvements in synthetic rubbers, then we will always need natural rubber.

<End Segment 2> - Copyright © 2012 Densho. All Rights Reserved.