<Begin Segment 1>

MN: Now you've done a lot of research on this guayule project.

GK: That's right.

MN: Can you give us the basics of this whole project that Manzanar... for example, what is the Intercontinental Rubber Company?

GK: The Intercontinental Rubber Company was set up to provide a domestic source of rubber for the United States. At the outbreak of the war, most of the rubber came from tree rubber, which is Hevea brasiliensis. And when imperial Japan took over Southeast Asia, the United States no longer had access to that tree rubber, and that was a serious problem for the United States. Because in order to wage a war, you need natural rubber, and you need it for airplane tires; you need it for truck tires; you need it for sealants; you need it for all sorts of important commodities that are required not only for domestic use but also for war. And without it, you can't really successfully wage a war. So it was an emergency commodity. U.S. Congress set aside thirty-seven million dollars to do research and grow the domestic source of natural rubber. And so what they decided to do was to purchase the Intercontinental Rubber Company that was centered in Salinas, California. And they were already growing the guayule rubber and the United States was already using some of that, but they wanted to ramp up production. They got high school kids and local communities involved, they bought up land in the Salinas Valley area and other places in order to raise the crops. So it was a huge industry that was brought into, brought together. Now, the Manzanar Guayule Project, sometimes it was called the Little Guayule Project, now, their goal was not to produce rubber. Their goal was to do research on improving the guayule plant so that they can find a strain of guayule that would grow better, that would grow on marginal lands, that would produce better rubber and things like that. And the other goal of the Manzanar Guayule Project was to see if they can produce the plant from cuttings, because that had not successfully been accomplished. Because if you have a rubber plant that had a high rubber yield, they would like to make cuttings from that plant so that they could grow more plants from that. If you depend on field pollination, you don't know what you're going to get. So even if you harvest a plant that has a high rubber yield, you don't necessarily, you're not necessarily going to have seeds that are going to grow into plants. But if you grow plants with cuttings from that plant, then you have a much better shot at finding a good quality plant that you can extract better rubber from.

MN: So what was one of the problems, though, that the Intercontinental Rubber scientists were having that the Manzanar people were able to overcome?

GK: Well, the Cal Tech scientists were actually wanting to work with the Intercontinental Rubber Company, the growers, to try to improve the quality of the plant. The Intercontinental Rubber Company, which was taken over by the U.S. Department of Agriculture, they wanted to just produce the rubber. They want to grow the crops, they didn't want to invest as much time and effort into improving quality because there was this emergency situation, it would take a couple years to get the crops grown to a size that would be harvestable. So they wanted to focus more on just production and not on research and development. So the Manzanar program was more like an R&D program. They did research, they studied the chromosomes structure of the plant that was done by Dr. Masuo Kodani from UC Berkeley, and he was at Manzanar studying the chromosome structure, and he also trained my dad to do the karyotype analysis, which is the chromosome analysis. And they worked on trying to hybridize guayule with other plants, larger plants, for example, to see if they can get the rubber produced in plants that were larger that would have a higher rubber yield and things like that. So these were some of the projects that they worked on. One of the challenges was to try to grow the rubber from cuttings, because it had not successfully been done before. And as I said, I think we got a plant that has an extraordinarily high rubber yield. If you can get cuttings and grow plants from those cuttings, then you can grow a large crop with all high rubber yielding plants. 'Cause some plants don't yield very much at all and others do. So this was another goal. And this work was done by Tomoichi Hata, sometimes he was nicknamed "Green Thumb Hata," and my dad both grew, they were able to develop techniques to grow these plants from cuttings.

MN: So once they found this high yield rubber plant, it had to get ground up, but they had the cuttings also? They saved the cuttings, and then didn't they ground up part of the plant, too?

GK: Yeah. The cuttings that they started off with came from plants that were kind of cut from, they were kind of mowed off the tops. These are plants, these cuttings were from the tops of plants that were kind of discarded because the leaves don't have very much rubber, okay? And so initially when Robert Emerson and Hugh Anderson went to Salinas to try to obtain some seed to start the project at Manzanar, they did not have enough seed to give them. So they, instead, they gave them some cuttings and they picked up gunnysacks of pretty much the mowed tops of plants, and parts that don't contain any rubber. And so they brought the gunnysacks to Manzanar, and the internees that were working on the guayule project, they carefully went through and examined the cuttings, the cut tops, and then they trimmed the side leaves and then they prepared them as cuttings and they were able to use some rooting hormone, which was a pretty recent discovery at that time. This is something that they were working on at Cal Tech, and they were able to get these cuttings to grow.

MN: Because the scientists at Intercontinental, they couldn't get any cuttings to grow, right?

GK: No, they didn't think that it was possible. But some workers in Mexico had earlier claimed to be able to do it, but they never really produced any big quantity of it. They claimed that they were able to, but the Intercontinental Rubber Company personnel, staff, they weren't able to duplicate those attempts. But they were successful at Manzanar. They were able to get eighty percent of the cuttings to take and grow roots, so they were very successful.

MN: So now, once they found a rubber plant, guayule plant that has a lot of rubber in it, what did they do with that? How do they get the rubber, and how did they improve the machine that you were sharing about?

GK: Okay, yeah. The other research projects involved the purification and extraction of the rubber once they grew the plants, and that's another improvement that they made at Manzanar. There was a man named Homer Kimura, and he was a mechanical engineer. And he designed a milling machine that was designed after a Jordan type paper mill, type of mill that could mash the fiber of the guayule to fine enough to where they can separate the rubber from the plant. Now, the difference between guayule and Hevea tree rubber is that in tree rubber, it's very easy to extract the rubber because all you have to do is score the trunk. You score the trunk like this, and the sap from the bark would just leak out, sort of like the way you harvest maple syrup. And then you just hang a bucket underneath that, and the sap just drips into the bucket. This is a labor-intensive procedure, but in places where it's grown, labor is very cheap. If we were to grow Hevea tree rubber here, and we were to pay minimum wage for the workers, we would not be able to afford that rubber, and then guayule would be very competitive that way. Because the advantage of guayule rubber is that it can be mechanically planted, harvested, everything can be mechanized. That's one big advantage of guayule rubber. And also it can be grown on marginal land so it doesn't compete with other commercial crops. So there are a lot of advantages.

MN: So that answers the questions of why Hevea rubber wasn't planted over here.

GK: Well, yeah, it's a tropical plant. And also during the war, Hevea brasiliensis, as the name implies, originated from South America. And so for a while we were getting South American tree rubber, but someone had the idea of, well, let's grow it in Southeast Asia. And it was a good thing they did that, because the South American crops, most of the crops were wiped out by a blight, which is a type of fungus. And so during World War II, we did not have access to South American rubber because the tree rubber in South America had been pretty much obliterated.

<End Segment 1> - Copyright © 2012 Densho. All Rights Reserved.

<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.

<Begin Segment 3>

MN: Now I understand you incorporate this into your teaching class.

GK: Yes, I do.

MN: How do you incorporate this?

GK: Well, I teach a class in cellular physiology, and latex being a plant product, what I can do is take some guayule stems that I get from my dad, and put it in a Waring blender. The blender takes the place of the Jordan mill. Grinds up the bark and the stems where the rubber is contained, and you turn it on for about twenty minutes and you get a solution containing about fifty percent ethanol and a little bit of... sodium... no, it's not sodium. I forget the chemical. Anyway, I mix it in a special solution containing a chemical with sulfur in it. I think it has nitrogen and sulfur. Anyway, and what happens is that you mix it in a blender, and what happens is that the latex, after it's separated from the fiber, it'll float to the top. And then what I do is I'll take a little scoop, and take out the rubber, and then just press it together, press it together and just toss it and it bounces. It's like in twenty minutes you can have, you go from stem, guayule stem, to a bouncing rubber ball. Takes about twenty minutes.

MN: Now did your father's research inspire you to go into research yourself and to go into academia?

GK: No. [Laughs] He didn't want me to become a bookworm actually, and I was not encouraged. But on the other hand, I was exposed to a lot of animals, we raised all kinds of animals as pets, we had snakes and scorpions, possum, I caught a woodpecker once. Just all kinds of animals we had growing up. We had a horny toad, praying mantis. But anyway, so my twin brother David and I were always interested in animals. And we also used to collect abalone from the seashores. So I became interested in marine biology, so that was one of the things that I became interested in. And also when I was in junior high school, I was going to be an artist until I got to junior high school, first science class, and I was just fascinated by looking at microorganisms under the microscope. And I took a little Brownie box camera and took pictures with a Brownie box camera through the microscope, and that was my science project, and it won first place. So I became interested in science at a pretty early age. But the transition, key in transition was in junior high school.

[Interruption]

GK: When we grew up, my twin brother and I grew up, we were interested in raising animals. We usually had snakes of one kind or another, garter snakes or king snakes. One time we had a possum, we had scorpions and praying mantises. We would feed praying mantises by dangling a spider in front of it and the praying mantis would eat it, we'd watch it. We just did things like that.

MN: Yeah, your mother said you two were the holy terrors when you were younger.

GK: Yeah, yeah, when we were younger, yeah. We'd work together, we'd move chairs so that we could climb up to get things. People would be warned, but they would put things up high and my brother and I would move a chair to get to it and stuff like that. So we had a reputation.

MN: Now how did you get interested in your father's guayule project?

GK: One year they asked him to give a presentation, and so he asked if I would help with the presentation. And so what I did was I put together a poster. And as I put together the poster, then I became more interested in the project, and so I started to do some research on it.

MN: How old were you at that time?

GK: Oh, geez, it wasn't that... it was relatively, I guess I must have been in my forties. It wasn't when I was young. I was already a professor.

<End Segment 3> - Copyright © 2012 Densho. All Rights Reserved.

<Begin Segment 4>

MN: Anything else you want to share?

GK: Yeah, I want to share one other incident that happened at Manzanar that my dad didn't seem to remember very well. Because of the success of the Manzanar guayule project, there were some articles written about that success. One article was written in the Washington Post, another article was written that was even blocked from publication because it praised what the Japanese Americans were doing in contributing to the war effort. But because their success made, the articles made the Manzanar success, that story was also embarrassing for the Salinas group if you were to compare the two. But the article should have emphasized the contributions that were being made by the Salinas group, because they were producing most of the rubber that was needed. The Manzanar group wasn't producing any rubber. They were doing research on the way to improve the quality of the rubber. And so these two groups were working... they both were adding some value to this enterprise. But because the articles were written in such a way that praised the Japanese Americans at Manzanar but kind of, and embarrassed the Salinas group, it, I guess, ruffled a few feathers. And so one of the things that happened was that one of the councilmembers of the Salinas Chamber of Commerce wrote a letter to J. Edgar Hoover to investigate what the Japanese were doing, and accused the Japanese Americans of sending rubber seeds, guayule rubber seeds back to Japan. They were just accusing them of all kinds of espionage and stuff like that. But anyway, so what happened was that they decided that, the camp director decided to shut the project down. So he ordered the water and the electricity shut off at the Manzanar guayule project. But what they didn't realize was that my dad and Swish Ogura snuck in at night 'cause my dad had a key. They snuck in at night and kept the plants alive. So it cut off for probably a few weeks, no water, no electricity except at night when my dad and Swish Ogura were in there watering the plants to keep the project going. And so I wanted to make that point, that their success came at a cost. There was a lot of distrust, and also at the end, when Congress was given a report, the Emergency Rubber Project, given by the Salinas group, the USDA, basically, about a paragraph was written just mentioning that there was some work done at Manzanar. And so they were not given any recognition or credit for the work that they had done. And one of my interests in doing research on this particular project is I'd like people to be recognized for their accomplishments. The Wind Talkers, the Navajos, were not given any credit for their work, the Tuskegee Airmen were not given credit for their work for a long time. The women aviators were not given credit for their work for many, many years. It was only after, many, many years after the war that people were recognized for their contributions. So that's how I got interested in this project. I really wanted to see people recognized.

And also probably one of the most important people to recognize is Robert Emerson. He dedicated a lot of his time and effort to support the Japanese Americans interned at Manzanar. He would bring back fruit and vegetables, whatever the workers wanted. He would go and pick the satsuma plums that were requested by some of the workers, he'd hand-pick 'em himself. He would ride his bike to and from his home in Cal Tech in order to save on the gas ration coupons. Because at the time, gas was rationed, and you could only buy so much gas with the coupons that you had. So he saved his gas coupons so that he could drive up to Manzanar, so that he can work with the internees to help them with the project. And I believe, in my opinion, he had a lot of knowledge of plants. He was a plant physiologist, so he was a pioneer in photosynthesis research, one of the most important areas of cell physiology, is photosynthesis research. He was one of the leaders. He made some very important discoveries. But he had to put some of that research on hold to help the Japanese Americans at Manzanar, and I want him to get full credit for his contributions.

MN: But he must have seen something very special with your father because he got special permission for your father to go out in '44.

GK: Yeah, so he actually wanted... he wanted my father to actually become a graduate student. But I think what happened was my dad happened to see a check that one of the, I guess, professors had, a paycheck or something like that, and he says he can make a lot more money doing gardening work, because professors at that time were not being paid very much. And so here I am, a professor. [Laughs]

MN: But it's very prestigious.

GK: Well, yeah, but you get prestige or money. Like if I were a researcher at a pharmaceutical company, I could probably make twice as much, but I would not have the freedom to do the research that I'm interested in. That's the difference. So you have advantages and disadvantages. So I think everything worked out, I enjoy the work that I do.

MN: I'm sure your father's very proud of you for bringing in the guayule project in your lectures.

GK: Yeah, and so yeah, the students are amazed. It's a nice, quick demo, takes about twenty minutes. You take just branches of a desert shrub, you shred it up, you put it in a blender, mix it with sodium sulfite and a little bit of ethanol. And you grind it up, after twenty minutes, the latex floats to the top. They're called guayule worms 'cause they're kind of worm-like in shape. And then you just gather up, you can just reach in and press it together, press it together, and when you press it together it adheres and you can form a little rubber ball. From stem to ball in twenty minutes. It's an amazing demonstration, actually.

MN: During this lecture, though, do you share that it was, this was done in Manzanar?

GK: Yes, I do. I talk about the contributions made by the internees and also by Robert Emerson. I give them the whole history, I'll give them the one hour of lecture just talking about the topic. And it's usually the students' favorite lecture.

MN: Do you ever have your father come over and do any lectures?

GK: Not at Cal Poly. But we have done demonstrations together for the Manzanar reunion, we did a presentation. And we've been invited to different groups to speak, mostly in Southern California. And we gave one presentation at the interpretive center. Actually, I think a couple presentations.

MN: Okay, thank you very much. Is there anything else you want to add to this?

GK: No, I think that's about it.

<End Segment 4> - Copyright © 2012 Densho. All Rights Reserved.

<Begin Segment 5>

[Demonstration of extracting rubber from guayule]

[Cutting apart guayule plant]

GK: All right, let me cut this big branch off here. Okay, then you can start. Okay, right now I'm cutting the big branches. I'm cutting the branches so that... we don't want to deal with the leaves. Leaves do not contain any latex. So we're just gonna strip the bark which is the easiest part to extract the latex from.

So now we're just shaving the bark. Shaving the bark, this is the part that contains the most latex. The latex is trapped inside of the tiny cells, and most of it is in the bark. Some of it is in the stem as well. And the latex is also found in roots of the guayule plant. So at harvest time, if it's desired, they could dig up the entire plant and what they'll do is they'll boil off the leaves to get rid of the leaves and just process the whole plant. For this particular experiment, we're using, by the way, it's called the blender method that was developed by the Salinas Intercontinental Rubber Company. And the blender method is a very simple way to do field testing to find out how much rubber content a particular field has.

Akira Kageyama: And the rubber is right in the bark, underneath in here.

GK: Now, the tree rubber, in order to extract, get the latex from the tree rubber, all you have to do is cut a slit and the latex just, the milky sap is what is the latex. And latex is actually found in probably over 18,000 different kind of plants. It's the same kind of material that you find in poinsettia. And every time you break a leaf or a stem and the white milky sap comes out, that's latex. So latex is found in dandelions, it's found in figs, plants of the fig family has latex in it. People have actually used latex from plants like dandelions to make rubber. This is what the Russians use, a type of dandelion to extract rubber from. So guayule is a plant that is native to America that is a good source of rubber. But the plant itself is in the composite family, which is related to plants like the rose and dandelion and the sunflower, things like that. People have actually tried to hybridize, cross breed guayule with other type of composites like a sunflower. The problem is they can do the cross breeding and they can get plants, these hybrids, but they oftentimes, most often, do not produce enough rubber. But they make big plants. Okay, so all these little strips of bark will be accumulating. When we're done, we'll have a little pile of bark strips, then we'll run it into the blender.

MN: I learned something new. I didn't know poinsettia... I mean, now it makes sense 'cause it's kind of sticky.

GK: Yeah, the milky sap. Any plant that has milky sap, most of that is latex. And the milky sap or latex of plants, they serve a function. One of the functions is it's used probably to protect the plant against insects. Some of these milky saps are very, they're very irritating. I don't know if you remembered, but remember the episode of, I think it's Crocodile Dundee where he takes the saps from a plant and he... no, it was not Crocodile Dundee. The Gods Must be Crazy. Anyway, they used the sap from the plants, the guy, who's a botanist, is studying in Africa, and he shoots the tree and the tree leaks the sap onto the bad guys, and the bad guys, once the sap gets on them, that's an irritant and the guy's kind of scratching and itching.

MN: Now I know why... I had no idea that latex was in other plants like the dandelion.

GK: Yeah, it's in a lot of plants. Like I said, over 18,000 plants.

MN: And now I know why it's stickier, like you said, it's irritating. I know why.

GK: Yeah, you know like jasmine, night blooming jasmine has the white milky substance. It's very common. And also it's sticky. Now, the way guayule was discovered is that Native American Indians used to chew it, and they used to have these communal chews, and they would use the latex to make the rubber. And when Columbus discovered America, 1492, he noticed that Native American Indians were... he didn't actually land on the mainland, but in the island that he landed on, he noticed that kids were playing with this rubber ball like structure, and took samples of it back to Europe. When the European, Spanish European conquistadores came to the New World, they also noticed the rubber balls. They had a ball sport that was sort of like soccer except they had to, it was combination of soccer and basketball where they had to, without using their hands, they could use their head, shoulder and foot or hip to maneuver a rubber ball through a stone hoop which was a stone circle. They had to try to get it through that hole. So it's a stone hoop, so that made it look like basketball, but because they couldn't use their hands, made it look like soccer. But anyway, so this sport was in practice throughout Mesoamerica. And the stakes were a lot higher then, because the losing, it was either the losing team or the captain of the losing team would lose his head. And that was part of the sport. Fortunately, they don't do that today.

MN: So this is native to... I mean, Europe didn't have any rubber at the time?

GK: Well, they had rubber-producing plants, but they never made rubber. They had, they didn't know about it. So this is an invention of Mesoamerica, basically. So I know a lot of people like to give credit to all major inventions to one group or another. The Chinese invented gunpowder, fire was first developed in Africa, the use of fire, and that helped the spread of mankind to the other continents. Well, Mesoamerica can be credited for inventing the use of latex to make rubber. And they made waterproof shoes, they made waterproof other items that they could wear that was waterproof, they made waterproof containers and things like that, and rubber balls. At this time, Europe was using, they had ball sports in Europe at the time but they were not using rubber, they were using bladders and other, like pig bladders and things like that, they were inflatable. But it was a very exciting thing for the European explorers to come to the, take this new product back to the New World. And the term "rubber" was used because it was a name given to a product that was used to erase things that were written with a pencil, like an instrument, they would use a thing and they would call it "rubber," because you would rub the writing off to erase it. So that's how the term "rubber" came about. But rubber is actually made from, latex is the rubber molecules. Rubber is actually made from latex, and latex is a suspension of these polymers made up of what are called isoprene units. So isoprene is a chemical that is made by the plants, and if you polymerize it, it makes a stretchy molecule. So the molecule itself stretches. And to make rubber, what is done is you need sulfur to cross link these neoprene or isoprene polymers by cross linking it with sulfur, gives it a stronger elastic product.

<End Segment 5> - Copyright © 2012 Densho. All Rights Reserved.

<Begin Segment 6>

GK: Okay, the plant that we are extracting latex from is called the guayule plants. It's pronounced guayule, a lot of people pronounce it guayule, it's actually guayule. And the scientific name for this plant is called Parthenium argentatum, Parthenium argentatum. So Parthenium is also the same family name that chrysanthemum belongs to that group, and other composites. Now, the plant has a lot of leaves and flowers on it. We're not going to be using this part of the flower with all the leaves and stuff because it contains very little latex. The latex is found primarily in stems, in particular the bark of the stems, and also in the roots. And so what we're going to do is just cut off all the small branches of the leaves, and take the main branches, and then we're going to debark the main branches by using just a typical little blade like this. And we're just going to shave off the bark. That's the easiest way to get the maximum amount of latex in a short amount of time. And this process takes about twenty to thirty minutes. So you go from the branch, then the stem and the bark, and then we're going to take the strips of bark and we're going to place them, we're going to run them through a meat grinder. The same kind of meat grinder that someone uses to grind, make ground pork or ground beef. And so what'll happen is that the little tiny pieces, strips of bark, will look more like coffee grounds by the end of the process. The next step, we're going to take the ground up product and place it in a Waring blender. The blender will take the place of the Jordan mill. The Intercontinental Rubber Company used a different type of milling process, they used what is called a pebble process which involved a lot of rocks. And the rocks would just grind up the stem into little tiny pieces. And the reason why the grinding process is required for latex extractions from the guayule plant is simply because the latex in the guayule plant is found within these little tiny latex channels, like little cells. They're enclosed in cellulose, they're surrounded by cell walls. They don't leak out if you cut it like the Hevea plant. The tree rubber, which is Hevea brasiliensis, all you have to do to get latex out of that plant is to cut the bark and the latex oozes out, sort of like maple syrup comes out of the maple tree. So the extraction of latex from the guayule plant was a lot more involved than simply cutting the bark. And so finally, after the ground up bark is placed in the blender, we will mix it with a little bit of ethanol, fifty percent ethanol and a little bit of zinc sulfate. And what the zinc sulfate will do, is the sulfur component of the zinc sulfate will help to cross link the isomers of the latex, cross link them to make a rubbery-like substance. So why don't we go ahead and grind the strips of bark up first? The next step is going to be setting up the meat grinder.

So here's the meat grinder, and we're just going to put the bark strips in here and we're grind it as if we're going to put meat in here, you know how you make hamburger, same process. [Demonstrates grinding process] Now, this doesn't look anything like rubber, does it?

MN: Is this what you do in your class also?

GK: Yeah. We have a meat grinder and we have a blender. So we have a little pile now, it looks like coffee grounds. Just a little bit more here. See, it would be easier if I had the Jordan mill, we could mass process it. But this is essentially what the Jordan mill and the blender does. It just grinds it into smaller pieces. The blender is required because this level of grinding doesn't break all the cells. It will not free up all the latex. In fact, it does very little of that. So we really couldn't get rubber out of this.

MN: Is this what the Intercontinental Rubber Company did, too?

GK: No, this is the technique that they developed for field testing. So in a field test, all you had to do was have a meat grinder. And they didn't have Waring blenders, I'm not exactly sure what they had in those days. I don't think they had portable blenders. Anyway, so they did field testing, and they had to grind their guayule shrubs up somehow. Okay, so that's about all I can get out of that little pile. So this is a very simple instrument, this is what it looks like. This comes apart like this. I'm going to get all these little pieces out, here.

MN: You know what this reminds me of, is gobo.

GK: Oh, really?

MN: Yeah, when they make the kinpira gobo.

GK: Okay, so now we're ready to put this in the blender. And here's a Hamilton Beach blender.

[Interruption]

[Blending guayule bark]

GK: And then mix that with a little bit of ethanol, this is fifty percent ethanol. We diluted it down from seventy percent, which is commercially available. This should be enough. And to the ethanol we're going to add a little bit of zinc sulfate. So this is premeasured for this volume of ethanol. And finally, we're just going to go ahead and hook up the blender to a power source, which is right there. I'm going to have to hold on to the top because it makes a little bit of noise, and I'll just start up.

<End Segment 6> - Copyright © 2012 Densho. All Rights Reserved.

<Begin Segment 7>

GK: Okay, after grinding up the guayule into little tiny chunks that make it look like coffee grounds, we placed it in the blender, and we added fifty percent ethanol, about 500 mls of that, and we added a little bit of zinc sulfate. The purpose of the zinc sulfate is that it is a sulfur compound. And what the sulfur does is it cross links the isoprene polymers, cross links them together. Because right now, they're linear molecules that are stretchy, but they're not cross linked. So the linear molecules that are isolated from one another are free to, they're suspended in water, and that's what latex is. They're suspended in aqueous cytoplasmic fluid, so it makes it fluid. But once you add the sulfur compound, what happens is that these linear polymers individually are stretchy, but they're loose and they're not stuck together. So what the sulfur does is it allows them to cross link, forms disulfide bonds. And so then we put it in a blender for approximately fifteen minutes and ran it at high speed. So now we have a solution that looks like of like, it's kind of coffee colored, it's got some bubbles in it, and if there's any latex in this solution, it should float to the top. But it'll float better if we add this solution to water. Because right now, it's harder to float in ethanol than it is water. So we're going to pour this into a beaker of water.

[Pours contents of blender into a container of water, then extracts a pulpy material and forms it into a ball and bounces it]

[Interruption]

GK: So what we did was we placed the guayule grounds, ground up guayule stems, we placed it in a solution of fifty percent ethanol with a little bit of zinc sulfate in it. And what the zinc sulfate does is it cross links the isoprene polymers. The isoprene polymers themselves are stretchy molecules. If you were to stretch an individual molecule, it would collapse back. So the property of the stretch of rubber is built into the molecule itself. But the problem with these isoprene polymers is that they are floating around freely in an aqueous solution, and that's what latex is. So the isoprene polymers in an aqueous fluid is that white milky substance that you find in a lot of different plants.

[Interruption]

GK: Okay, so we need the zinc sulfate because it has sulfur in it, and the sulfur cross links the isoprene polymers so they can form a congealed mass. And when that happens, it makes the substance more buoyant, and it'll float to the top if you pour that guayule cocktail, if you pour it in water, then the "guayule worms," they will float to the top. Normally what you would do is you would just take the guayule directly out of the vat and put the "guayule worms" in a bucket of water. And what we'll do is it will separate all the fibers that are floating in the guayule soup. And then all you have to do is press the rubber together, press it together and make a ball. And once you've done that, you have a ball. And what I usually do is I just toss it out and it just bounces on the floor.

MN: That is so awesome.

GK: Isn't it cool?

MN: Yes. How long would something like that last?

GK: Well, this is the blender method that was developed by the Intercontinental Rubber Company, and it's used for field testing only. So what they'll do is they take the shrub, they weigh it to get a wet mass weight, and then they take the rubber and they weigh it to find out what the percent rubber content of that mass that they started off with. So what we would have done here is we would have just taken the shavings of bark and we would have weighed that, because we didn't really take the rubber from the whole plant, we only took it from the bark in this case, and we would get a percent yield. And the percent yield would be something probably on the order of five percent, five to ten percent, and that's approximately.

MN: How did you test it at Manzanar? You didn't have a blender at Manzanar, did you?

AK: Yeah, we had a blender.

MN: You did the same kind of field testing?

GK: Also they had blenders.

MN: You did?

GK: I guess so. I didn't know that.

<End Segment 7> - Copyright © 2012 Densho. All Rights Reserved.