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Guayule Rubber Industry in Salinas, California, ca. 1942
BANC PIC 1962.006--fALB
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One year old plants.
Seed picking device. Knocks the seed off and collects it in receptacle in the rear by vacuum. (Seed is collected from two rows).
Another seed collecting device that was first developed collected the seed from one row. Apparently these machines are rather inefficient as they have only been able to collect ten seeds per plant, while it is estimated each plant can produce from two to five thousand seeds per year.
After the seed is dried, it is placed in air tight drums where it keeps almost indefinitely.
Mill at Salinas, California which cost $265,000.
Chopped shrub at the bin where it has been dumped from the wagons from the fields. Shrubs go through three sets of rollers before going into the mill proper.
Another picture of the mill.
The first settling tank. The wood silt becomes water logged and goes to the bottom. The rubber floats, together with some cork, the latter being removed by forcing water into the air cells of the cork under 350 pounds pressure, which sinks in the settling tank. This picture is out of order, and should be in following the next two.
Long tubular ball mills are used, using flint stones the size of the fist which come from Norway or Belgium, because of their hardness.
These giant crushers are filled with rocks. Chopped guayule is put in these tanks and rotated so that the rocks crush the wood pulp, and separate it from the rubber.
These stones, imported from Norway, are used as a primary part of the milling process. Search is now being made in America for stones having similar qualities of hardness.
The pulp from the crushers is then transferred to these water filled vats. The wood pulp sinks to the bottom and the rubber and cork rises to the top and is skimmed off.
Rubber being scraped from the trays after drying.
[Man and machinery]
Wet rubber being placed in the trays prior to drying.
Sheet of dried rubber before it is pressed in a box.
Rubber press which presses the rubber into blocks of 100 pounds each - two blocks to a box. This rubber contains about 18 or 20 percent resin and other impurities. One of the problems is the elimination of this resin and particularly, the elimination of the impurities. Dr. D. Spence is working on a plan of purification of guayule rubber.
Dr. D. Spence, well known rubber chemist and specialist, Major Evan W. Kelley of the United States Forest Service in charge of the Government project and Senator Sheridan Downey.
Major Kelley, Senator Downey and Dr. D. Spence. Dr. Spence advocates the planting of the seed thick in the spring and harvesting in the fall, and states that his experiments show that he could get 1170 pounds of pure rubber per acre, which he maintains can be produced at a great deal less cost, and a great deal quicker, than under the transplanting plan.
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