Grantville Gazette VI

by Eric Flint

  Latex is produced by several different African (and Asian) species of vines. To extract the rubber, the vine must be cut down, and unfortunately, when the price of rubber was high, this encouraged over-exploitation. The EB11 notes that the southern Sudan was "nearly entirely denuded." In consequence, the authorities in the French Sudan, the Congo, and in German Africa adopted regulations which limited when and how the vines could be tapped, and also required replanting. As the EB11 notes, these edicts can only be enforced "at considerable expense."

  Library research in Grantville will reveal some information on how to extract the guayule rubber. EA says that 3- to 5- year old shrubs are shredded. The recommended collecting technique is to mow off just the top, so that the same plant can be harvested repeatedly. The latex is leached out of the plant material with hot water.

  CE, on the other hand, says that the rubber is found in all parts except the leaves. It suggests that the collected plant material be "cured" (that is, left outside to ferment), chopped up, and macerated in water, after which the rubber is skimmed off the surface.

  Latex Processing

  The latex of the Para Rubber Tree is said to be about 41% rubber and 55% water (EB11); CE says 27%/70% and 36%/60%, respectively, for four and ten year old trees.

  Hevea latex can be stabilized by the addition of ammonia or sodium sulfite (CE), and then concentrated (much like separating cream from milk) for shipping. Rubber gloves and toy balloons are made by dipping molds into latex and then allowing the acquired layer to dry. This is usually done several times, to increase the thickness of the rubber, and then the dipped article is removed from the mold. However, most latex is coagulated into rubber at or near the collection site, and only later shaped into a final product.

  The Hevea latex is unstable; the rubber will gradually separate from the water, a process called "coagulation." This can be expedited by addition of an acid, since Hevea latex is alkaline. Crude Hevea plantation rubber was typically 94.6% rubber, 2.66% resin, 1.75% protein, 0.14% ash, and 0.85% water.

  Grantville's only source of information concerning the handling of latex from other rubber trees is the EB11.

  Castilla latex has the advantage that the rubber can be separated from the water by centrifugation. However, the standard processing method is to strain the "milk" through a wire sieve, add an alkaline plant juice (the Castilla latex is acidic) to cause coagulation, flatten out the coagulum to remove water bubbles, and then let the material dry for a few weeks.

  In Africa, there was the curious practice of letting the Funtumia latex sit for half a month, covered with palm leaves, in a hollowed-out tree trunk. The trunk absorbs the water component, leaving the rubber behind. Another approach is to dilute the latex with water, and then heat it to coagulate the rubber. The Africans also employ plant-derived coagulating agents, but the bare reference to "Bauhinia leaves" is not likely to be of much use to us.

  Perhaps the most important characteristic of Funtumia latex is not mentioned by the Grantville sources; it is very stable (Polhamus, 264). The same is true, to a lesser degree, of Castilla latex (102) and Ficus latex (264).

  * * *

  A number of natural latexes have a high resin content, and, if the resin is not removed, the rubber will be considered inferior. In 1911, solvent extraction of the resin was considered commercially impracticable, but that of course is very dependent on the price of the solvent as well as on the price difference between high resin and low resin rubber. EB11 shows that Ceara, Castilla and Ficus rubbers have average resin contents of 10.04%, 12.42%, and 11.8%, respectively.

  Guayule rubber has a substantially higher resin content. According to CE, it is 20-25% for rubber extracted from the wild shrub, and about 16% in the case of the cultivated varieties. EA gives the resin content as 13-18%. It acknowledges that solvents have been used commercially to extract the resin, but does not provide particulars. The EB11 entry for "resin" says that it is "mostly soluble in alcohol, essential oils, ether and hot fatty oils." Curiously, CE states that the resin content is actually advantageous "as an aid to processing" when guayule rubber is blended with Hevea rubber.

  Rubber Processing

  A general problem with natural rubbers is the presence, inadvertent or deliberate, of gross impurities (dirt, chips of wood, leaf material, etc.) Such defects can be mitigated by filtering the latex (see above) and by washing the rubber.

  The rubber initially conforms to the shape of the collecting cup and is called a biscuit. The spongy mass of rubber is washed (with hot or cold water) as it is passed between grooved rollers (EB11, Fig. 8), producing ribbed sheet. CE suggests use of a series of rollers, with progressively finer corrugations. It was then hung to dry. If a smokehouse is used, the product is called smoked sheet. Or it can be dried without resort to smoking, producing crepe rubber. The rubber can be softened with heat and compressed into blocks.

  Additional shaping may be carried out in factories. After softening (if necessary), the rubber may be calendered (rolled), molded or extruded. By suitable incorporation of air, sponge and foam rubber can be formed. (WBE)

  The rubber is warmed or masticated to soften it. The masticating machine (EB11, fig. 8) kneads the rubber, and, as this is happening, any desired additional ingredients (e.g., sulfur, carbon black, fillers, anti-aging compounds, colors, and oils), are mixed in. The rubber can then be softened further by heat and pressed into molds. One type of masticator, the rubber mill, has two rollers rotating inward, but at slightly different speeds. A more advanced masticator, the Banbury mixer, has rotating blades. (EA)

  The last step in the preparation of commercial rubber is vulcanization, since the vulcanized rubber cannot be further shaped. Without this treatment, rubber is an unsatisfactory material; it is brittle when cold and sticky or gooey when hot. Goodyear overcame these problems with his vulcanization process. In vulcanized rubber, the polyisoprene chains are cross-linked by disulfide bonds. Several methods of achieving vulcanization are described in EB11. In one, the rubber is immersed in molten sulfur for an hour or so at 140 deg. C. In another, the rubber is placed in a lead chamber with chloride of sulfur. In a third, it is cooked with a solution of calcium polysulfide at 140 deg. C. The use of excess sulfur or heat results in a hard, inelastic rubber (ebonite).

  The Microsoft Encarta CD, which is probably available in Grantville, mentions that vulcanization can be accelerated with aniline and thiocarbanilide.

  Rubberized cloth can be prepared by dissolving the rubber in one of its solvents ("carbon bisulphide, benzol and mineral naphtha, carbon tetrachloride, and chloroform") and then using the solution to coat the fabric. The original MacIntosh process used naphtha.

  The Logistics of Rubber Collection

  Most rubber plants require a tropical climate. Once these plants have been located, we have four choices. First, we can simply trade with the natives for it. Second, we can go out into the hinterland and collect the latex from wild plants ourselves. Third, we can establish local rubber plantations. Finally, we can collect the seed (or other propagatable plant materials) and cultivate the plant elsewhere. This could be at a different tropical location (presumably, one more advantageous to USE), or in greenhouses back home.

  All of the high-ranking rubber sources listed at the beginning of this essay have been cultivated, at least on an experimental basis. Most have also been transplanted, at least for trial purposes, to another part of the world, e.g., Hevea, Castilla and Manihot to Asia and Africa, Funtumia to Trinidad (Christy, 237) and Asia (EB11), Guayule to the Soviet Union, and the Russian dandelion to the USA.

  However, because Hevea is the most important source of natural rubber, it behooves us to take a closer look at why plantations in Asia and Africa have supplanted the collection of wild rubber in Brazil.

  Collecting Wild Hevea Rubber

  In our timeline, Brazil was not an important source of rubber after 1920. That is because the British successfully transplanted Hevea brasiliensis to Asia. The wild Brazilian rubber
was unable to compete with the plantation rubber because its collection was too labor intensive.

  There are limits to how much rubber can be collected from wild Hevea trees. They are widely dispersed in the rainforest, usually only two or three trees per hectare (Dean 10). The trees had to be found, and then connecting paths had to be created by hacking through the dense rainforest vegetation with a machete. Usually, a single tapper would clear two or three trails of 60 to 150 trees each. (Dean, 36-37) The tapper traversed one trail each day. In contrast, on a Hevea plantation, one tapper might process 400 trees in a single day (EA).

  Large-scale collection of wild rubber was limited by the labor supply. The Amazon jungles were thinly settled, so workers had to be brought in from elsewhere. These strangers were vulnerable to the many diseases and other pitfalls of life in the Amazon, and labor turnover was high. Even in 1907, "each ton cost five lives" (Dean, 44).

  In the lower Amazon, and on the coast, where rubber trees were more accessible, yields declined substantially (from ten to two pounds of rubber per tree per year), as a result of overtapping (Brown, 104). The overtapping was evident by 1853, just eight years after the vulcanization process expanded the rubber market (Coates, 58-9). This forced collectors to go deeper into the Amazon, increasing provisioning costs.

  In southeast Asia, plantations reduced labor costs, because a single worker could tap more trees in a day. Logically, the Brazilians should have started their own plantations. Unfortunately, even though it is native to the region, and hence well adapted to the local soil and climate, Hevea brasiliensis cannot be successfully cultivated in plantations in Latin America. The Microsoft Encarta Encyclopedia on CD in its "rubber" essay contains these fateful words: "About 99 percent of plantation rubber comes from southeastern Asia. Attempts to establish significant rubber plantations in the tropical zone of the western hemisphere have failed because of widespread tree loss as a result of a leaf blight." (More information about the attempts to establish Hevea plantations in Latin America appears in Appendix 3.)

  Even without the South American Leaf Blight, it is doubtful that Brazilian plantations would be competitive with southeast Asian ones. In the early 1900's, the daily cost of labor and provisions in the Orient was perhaps one eighth of that in Brazil (Akers).

  Once the demand for rubber outstrips the level that can be produced by wild Hevea brasiliensis trees, it will be essential to establish Hevea plantations elsewhere, to produce rubber from other botanical sources, or to manufacture rubber synthetically.

  The Transplantation of Hevea to Asia

  Wickham collected about 70,000 seeds in Brazil in 1876. These were planted at Kew Gardens, but only 2,600 germinated. The seedlings were forwarded to Ceylon and thence distributed elsewhere in Asia.

  Some of the sites chosen, such as Calcutta, were poorly suited for Hevea. Fortunately, we have the benefit of hindsight; we know roughly where Hevea plantations were successful. For example, that map in CE also shows the major producing areas for plantation rubber in India, Ceylon, Burma, Thailand, and the Malaysian-Indonesian region.

  It is also extremely important that all attempts to transplant Hevea be made strictly with seeds, not with cuttings that might carry abroad the deadly fungus.

  Moreover, speed is of the essence. EB11 warns that "the seeds readily lose their vitality," and suggests that they should be "loosely packed in dry soil or charcoal." According to Polhamus (273), in the open, the seeds are only viable for seven to ten days, but packed in charcoal or sawdust, they can be expected to germinate if planted within four to six weeks.

  Collecting Other Wild Rubbers

  Information is limited (and unavailable in 1632), but Treadwell says that in the British Honduras in the twenties, one man working eleven days in fifty acres of jungle could collect 700 pounds of Castilla rubber.

  Rubber Plantation Management

  Most of Grantville's information concerning rubber tree cultivation relates to Hevea. EA suggests that the Hevea trees be raised in a nursery for one year, then planted outside in rows about 15 to 20 feet apart. It says that, after casualties from disease, accident, and so forth, there are about 150 trees per acre (see also Brown 104). The trees are mature enough to be tapped when they are five to seven years old; tapping can continue for another thirty to forty years. The older trees are more productive.

  It will be found that the trees vary in productivity. This variation can be exploited in a number of ways, including cross-breeding and bud grafting. According to CE, "Bud grafting consists of grafting a dormant bud from a proved high-yielding tree to a seedling one to two years old. After several months the bud forms a healthy bud shoot termed a scion, which grows to form the new tree. The seedling is then cut off just above the bud patch." A photograph shows how the foreign bud has been inserted into a "bark flap."

  Hevea has been grown in African and Asian plantations alongside other crops, notably cassava, sesame, ground-nuts, tea, coffee, cocoa and tobacco. The EB11 advises against this interplanting, except in the case of cocoa.

  * * *

  The first rubber plantation in southeast Asia raised Ficus elastica (first planted in 1872), because at that time, before Ridley devised his improved tapping scheme, it yielded more rubber than did Hevea brasiliensis (Joshi). The most successful Ficus elastica plantations have been in Asia, in the mountainous districts of Assam, Ceylon and Java. (EB11)

  * * *

  The "Angiosperms" article in the modern EB claims that Funtumia elastica has the advantage that it will grow in parts of tropical Africa which are too dry for Hevea. It nonetheless discourages the cultivation of Funtumia elastica, declaring that it must be grown for twenty years before commercial yields become obtainable. However, this source is plainly in error; Christy's African Rubber provides ample data that Funtumia yields rubber even when it is just five years old, although he recommends that tapping not commence until the next year. It is regrettable that this specialist knowledge will not be available in Grantville, and hence the development of Funtumia plantations in the new timeline may be delayed.

  * * *

  There is only limited information available to Grantville on the cost of production and, of course, the old timeline data is of limited relevance to the hybrid economy created by the Ring of Fire. For what it is worth, EB11 reports that circa 1911, the cost of Ceylonese plantation production was about one shilling a pound, for a field planted at a density of 150 trees an acre. However, another source (unavailable in Grantville) pegs the Asian (Malaysian) plantation cost somewhat lower; just 0.75 shillings a pound. In contrast, the cost of Brazilian rubber was four shillings a pound. (Coates, 156)

  The price of rubber was then about 2.5 shillings (US$1.25) per pound.

  For Castilla plantation rubber harvesting in northern tropical America in the Twenties, Treadwell says that the cost of production was 25 U.S. cents a pound. (32)

  The Geopolitics of Foreign Rubber

  One of the problems of developing a post-Ring of Fire (RoF) rubber industry was expressed in an aside to readers by Mike Stearns: "the natural resources were halfway around the world under the political control of other nations . . ." (1633, Chap. 34)

  Even the citizens of nations that are allies in Europe (the English and Dutch in the old time line, "OTL") may take advantage of each other elsewhere. This is an era in which the term "cutthroat competition" is taken literally, and there is "no peace beyond the line" defining the bounds of Europe.

  Even if you didn't have to worry about the predatory habits of your fellow humans, there is the question of disease. Up-timers are perturbed enough by the public health conditions of down-time Europe, but the rest of the world is worse off. The mortality rates are three to four times higher in the Indian Ocean area, ten times higher in the American tropics, and fifty times higher in West Africa. (Landes, 170)

  The New World

  Let us first examine the situation in the New World. The Castilla Rubber Tree grows in "New Spain" (in Mexico and Central Am
erica) and in "New Castile" (which includes western South America). All of these regions are claimed by Spain. Legally, there is a ban on immigration, and even trade visits, by foreigners. All transatlantic trade leaves from Seville, takes cargoes of manufactured goods to specified colonial ports (Veracruz in Mexico, Portabello in Panama, and Cartagena in Columbia), and brings gold, silver and other American products back to Seville.

  Only a Spaniard can buy a licencias de toneladas (the right to ship a certain number of tons of freight on a ship heading out to Spanish America). However, he could be acting as a front man (testaferro) for a foreign merchant. A particular kind of testaferro was the cargadore (the word now means a porter), who actually went on board with the cargo and made sure it was sold for a good price. A foreign merchant could also have a Spanish agent who was a resident of one of the American ports of call for the Spanish trade fleets. Another trick was to sell a foreign ship (with a cargo) to a Spanish figurehead, who would rename it, obtain a sailing license, include it in the Spanish trade fleet, and ultimately sell it back to the original owner (at a price which included a profit on the cargo). (Braudel II, 152-3; Solana) As early as 1608, two-thirds of the shipments to the Indies was of foreign goods (msu.edu).