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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.