At the end of 17th c. the oil-bearing rose was already cultivated in the vicinities of Kazanlak. The flowers were distilled to obtain rose water and small quantities of attar, floating over the rose water could also be collected. The rose oil produced at that time had a weaker fragrance and contained a lot of carbonic constituents, or paraffin, called stearoptene. It froze at room temperature. The liquid constituent of the rose oil, called eleoptene, represents some 80% in the pure rose oil. The kind of rose oil that was extracted in small quantities at that time is now called "direct (raw) rose oil". The technology used then was chiefly intended to produce rose water.
By a lucky coincidence, exactly at that time a great demand for rose oil arose in Western Europe. The rose oil was sold there at high prices, while the rose Water manufactured in Kazanlak at that time was exported to the Arab countries.
The people of the Kazanlak region soon became aware that the new planting, the oil-bearing rose could only bring profits if the main product after processing was the rose oil, rather than rose water and if it was sold in Western Europe.
So, the rose growers started testing new methods of distillation and finally one of them produced genuine rose oil. The Bulgarian rose oil hit the European markets. With the new technology, rose water was obtained only at the end of the entire rose-processing season as a by-product and in small quantities: 3 to 5 liters from a ton of flower material.
Distillation was carried out in tinned copper vessels, alembics, of 80 to 120 liters capacity. These vessels are in the shape of a truncated cone with two handles, with about 80 cm diameter of the bottom and 20-22 cm diameter of the top. The alembic type introduced in Kazanlak differs considerably from that of the alembics used in Iran especially in the design of its head. In the Iranian version, the head continues from the alembic into a hat-like shape, while in the alembics used in the Rose Valley it looks like a mushroom and is more similar to those used in Northern Africa.
The mushroom-shaped head is where the primary cooling is performed. It helps return the phlegm back into the alembic and liberate rose oil more effectively. The vapors are cooled in a special unit consisting of a wooden cask into which cold water is let.
A thinning pipe, set at 45°, goes from the head to the receiver, passing through the cask. It is in this pipe that the vapors are cooled. Craftsmen gradually improved the cooling unit, transforming the conical pipe into a bunch of 3-5 pipes.
The Iranian type of alembic has no special cooling unit. Cooling is done by air in a curved pipe which leads from the head to a can-shaped receiver dipped in water. The cooling technique introduced in the Rose Valley was intended to extract rose oil, rather than rose water.
Thus the rose oil became the main product of distillation there while in Iran the can-shaped receiver was used to collect rose water. In order to obtain as much rose oil as possible, the technology of rose stilling was constantly improved until finally one technology gained recognition. This technology was used for more than two centuries.
For each distillation the alembic was charged with 10-12 kg of rose flowers and 40-60 liters of water or residual liquid after cohobation or a mixture of the two) were fed through a sheet-iron funnel. The mixture was stirred. The water was added to the rose flowers in ratio 4:1 or 5:1, or 4-5 kg of fluid were fed for each kilogram of flowers. The head was then replaced, the alembic was put on the fireplace and the pipe of the head was connected to the pipe of the cooling unit.
The places of joining were sealed with clay, sometimes reinforced with bandage. It was believed that the clay that could be dug near the village of Koprinka, west of Kazanlak, was particularly suitable for the purpose, so people from all over the valley went there to get some. The bash (the first 5-7 liters of distillate obtained from rose flowers; the bottle used to collect the first distillate) bottle was placed under the spout. The adopted ratio in which rose flowers and water were then mixed, 1:4 and 1:5, is still used in the modern rose-processing technology. As soon as the bash bottle was filled, it was replaced by an ayak (the second 5-7 litres of distillate as well as the bottle in which it was collected.
As soon as the ayak was filled, the distillation process was complete. A total of about 10-14 liters distillate were collected within about 1,5-2 hours. The amounts of charged flowers and the distillate obtained were in ratio 1:0,85 to 1:1,20. Today this ratio is 1:1,3.
Distillation was carried over a slow fire and it took longer than the process by which rose water was obtained. The oil was liberated in the neck of the receiving bottle surier (a glass vessel with a thin long neck, most often pear-shaped, used to collect distillate and liberated rose oil).
The oil was decanted by means of a small metal spoon resembling a tiny funnel with a long handle. The distillate obtained in this process was added to another distillate and redistilled together with it. In this way the multiple distillation technology, which provides full liberation of the rose oil, was introduced. The technology was an original Bulgarian innovation.
The skills applied continually to create this original technology and to update the equipment, bore excellent fruits. Rose oil was obtained in much larger quantities. An average of 3000 kg of rose flowers produced 1 kg of rose oil.
The rose oil hit the markets as soon as the distillation of roses came to be done in the described manner. Initially it was exported through Constantinople. However, the majority of merchants in Constantinople were Arabs who were mainly interested in buying rose water. The merchants from Western Europe were those who started to demand rose oil.
The Bulgarian merchants gradually took the trade in rose oil in their hands. They turned to Europe to seek new markets. Kazanlak became the center of trade in rose oil. The first independent retail dealers appeared in Kazanlak and the surrounding villages. They bought rose oil in muskals and took it abroad thus packed.
In addition to estimating the fragrance, when purchasing rose oil, merchants began to use a more objective method of testing. They determined the freezing point of the rose oil by the Reaumur scale. The freezing point was called deredje and was the basis for bargaining the price. The price of one deredje, or one degree, was bargained for one kilogram of rose oil. The final price depended on the number of the degrees (deredjes).
Today, contrary to the beliefs in those times, most experts find that oil which freezes at lower temperature (yet within certain limits) is of superior quality, because the content of stearoptene is lower and the percentage of the fragrance-bearing alcohols is, respectively, higher.
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