Indigo Production in the Eighteenth Century

The production of indigo was important to the economy of eighteenth-century Spanish America. The indigo plant was grown and processed principally in Guatemala, Venezuela, and Mexico. While the largest area of production was Guatemala, Venezuela followed closely in production figures. Guatemala’s production during the last decades of the eighteenth century was from 1,200,000 to 1,500,000 pounds and was valued at about 1,250,000 pesos (almost $2,000,000.00). Venezuela’s output of indigo during the same period was nearly 1,000,000 pounds.¹

Though the importance of indigo to Spanish American economy has often been cited by historians, few descriptions of the manufacturing process of the blue dye are offered. Bernard Romans, an eighteenth-century naturalist, noted the process in British East Florida and recorded it in his Natural History of East and West Florida (New York, 1775). Romans limited his discussion to the method used by the British, but it is likely that the methods of production were similar in other areas, including Spanish America.

Indigo is a blue dye obtained from several plants. Natural indigo does not exist in the plants as such, but is obtained by the decomposition of Indican, a colorless crystalline glucoside. Indican contains, besides indigotin (the essential coloring property of indigo), various other substances unless it is purified. Indigo was the most important vat dye used by the British in the eighteenth century.

The indigo plant grew wild in East Florida, and its cultivation was undertaken on a large scale by all the British planters. The government of Great Britain even encouraged the manufacture of indigo by paying a subsidy to producers.²

The best indigo plant was called flotant or flora. It was light, pure, and hardened quickly. It was bouyant, easily inflammable, and its color was a fine dark blue inclined to be violet. By rubbing it with the finger-nail, it could be made to assume the color of old copper. The next best indigo plant was called violet, or gorge de pigeon. It was heavier in weight than the flora. Both flora and violet were used for dying linen and cotton fabrics. The type of indigo plant most desired by the planters, since it brought the highest price, was of a copper color.³ This was the heaviest of all the merchantable indigo plants, and therefore its residium was the best of the three from a planter’s point of view. This copper-colored indigo was especially sought by the manufacturers of woolen fabrics.

An indigo plantation was an insalubrious place. The stench of the work vats, where the indigo plants were putrefied, was so offensive and deleterious, that the “work” was usually located at least one-quarter of a mile away from human dwellings. The odor from the rotting weeds drew flies and other insects by the thousands, greatly increasing the chances of the spread of diseases. Animals and poultry on an indigo plantation likewise suffered, and it was all but impossible to keep livestock on, or near, the indigo manufacturing site. Nevertheless, the manufacture of indigo was a most profitable business venture anywhere.⁴

The manufacturing of indigo in eighteenth-century English Florida was not a complicated process, though it did require a certain amount of skill on the part of the workers. The actual culture of the plant required perhaps more laborious care than the manufacturing process. The indigo plant needed a rich, middling, loose type soil. The field in which it was to be planted was as level as possible. Indigo will, however, grow in any soil, but the plant especially favors rich, moist, hammock or oak land, thoroughly cleaned and reduced to a perfect garden mold. Soil preparation was the most laborious part of the plant culture, and was so important that a “good” crop was impossible without it.⁵

The best indigo seed was found in abundance in the Mississippi River region. About four bushels of seed was required for one acre of planting. The ideal time for sowing the seed was in early March, and continued until early in May, the wet season in Florida. If the seeds had been sown in early March, and if the season was favorable, five cuttings of the indigo plants could be expected between March and November. No cutting was done during hot, dry weather, for the hot sun destroyed the cut plants. The ideal time for cutting was the rainy season. As soon as the indigo bloomed it was cut ; the blossoms usually appeared about ten weeks after the seeds were planted. After the plants were cut they were gathered and tied into bundles, and carried to the indigo vats for processing.⁶

The processing vats were three in number, and placed in juxtaposition. The first was the larger of the three and was called the “steeper”; it was about sixteen feet square, and three feet deep. The second vat was called the “battery”; it was twelve feet square, and four and one-half feet deep. The third vat was of varying dimensions, but it was much smaller than the battery vat. Three vats of the above dimensions could easily handle seven acres of plants in one processing cycle. The vats were constructed of two and one-half inch cypress planks, and the joints, or studs, were made of live oak. The vats’ planking was well secured by seven inch spikes. Constructed as described, these vats could be expected to offer service for at least eight years.⁷

The eighteenth-century manufacturing process of indigo was relatively simple, though toilsome. The freshly cut plants were tossed into the steeping vat and covered with fresh water; then they were pounded with a heavy wooden instrument until they began to ferment. Fermentation normally occurred within eight to twenty hours, depending on atmospheric conditions. Once the fermentation began the plants effervesced violently, and the water in the steeper vat thickened and became purplish blue in color. The violent effervescence marked a turning point in the process, for when the turbulent bubbling occurred, the water was drained immediately into the beating vat whose edge was recessed directly below the steeper vat. The plants were used no further in the manufacturing process, though they could be, and often were, re-processed to manufacture saltpetre.⁸

As soon as the liquid entered the beating vat it was stirred by a process similar to churning. This fatiguing task was usually performed by Negro slaves, though horses were used on some of the larger plantations. A “beater” or “chumer,” as this laborer was called, would draw a large lever having one or two bottomless buckets at each end, up and down. The churning continued until the dyeing particles separated from the liquid, or until they congealed and formed a mass. It was this part of the process that required care and attention, for if the churning was stopped before the mass of residue was formed, a part of the dying matter would remain undissolved. If the churning process continued too long, some part of the residue would dissolve again. Experience in this part of the process alone could teach one when the indigo had been churned enough. The most common method of determining when the churning should cease was to pour some of the liquid into a phial or cup and observe whether the dyeing matter was inclined to dispose of itself or not. To hasten the separation of the residue, most English planters used lime water, but the Spanish, Dutch, and French used only pure water in the entire process.⁹

When the indigo had been properly churned the second part of the process was completed and the residue was allowed to settle to the bottom of the beating vat. The liquid was then drained through a cock fixed at a higher level than the residue into a ditch. The liquid was used no further. Only the residue and a small amount of liquid remained at the bottom of the beating vat. The residue was then drawn into the third vat through a drain cock located at a level near the bottom of the vat.¹⁰

The residue was left in the third vat from eight to ten hours, then removed and strained through a horsehair sieve. It was then put into conical shaped bags of cloth called “Hippocrates’ sleeves,” and hung in the shade to drain. These bags contained pure indigo, and at this stage the indigo took on the appearance of mud. When the water had been drained from the bags, their contents were dumped into shallow boxes and placed under the indigo sheds where they were allowed to dry in the shade. As soon as the indigo began to harden it was cut into square pieces with a thin bladed knife. The squares of indigo were left under the drying shed until they were completely dry and hard. This was the state of indigo when it was shipped.¹¹

The indigo was carefully turned three or four times daily while in the drying shed. Someone was required to drive the swarms of flies from the drying shed, for the flies would damage the indigo, particularly when it had not hardened sufficiently. Extreme care had to be exercised in determining when the indigo was completely dry, and that it was in the shade at all times. If direct sunlight touched the indigo before it was dry, all the tinting matter would be exhaled, and the indigo would be left in a colorless state and would turn the color of slate. Care was also taken not to allow the indigo to be near too much moisture, for extreme moisture would keep the indigo dissolved and cause it to rot.¹²

Even though the indigo grew wild in East Florida, tender care was given the plant during its period of growth. Two major problems confronted the planter during the indigo’s growing period; drought and caterpillars. For drought there was no remedy other than irrigation. The caterpillar was combatted in different manners. Many planters dug a trench about three feet wide around the infested part of the indigo field, and the plants within the infested area were cut, isolating the infested portion of the crop from the other. The caterpillars themselves were collected in buckets, drowned in lime water, and their substance was squeezed and strained through a hair sieve. This substance contained indigo also, and it too was placed in the drying shed and processed like indigo derived from the plant itself.¹³

After 1786 the entire indigo production of North America encountered almost ruinous competition from the British East India Company. In 1786 more than 250,000 pounds of Asian indigo was dumped on the London market by that organization. By the year 1810 the East India Company was capable of placing 5,500,000 pounds of merchantable indigo on the market in London with facility, all but wrecking the production from the Americas.¹⁴

Author notes