Plinth and brick application

From the time of the construction of the first stone-brick building in Kyiv at the end of the 10th century until the middle of the 13th century, the bricks used in Rus' took the form of thin and relatively wide tiles. In ancient Russian written sources, bricks were called by the Greek word plintha (variants - plint, plinf). This type of brick came to Rus' from Byzantium.

Brick production, which seems at first glance to be a very simple matter, actually requires special knowledge and a lot of experience. First of all, not all clay is suitable for making good bricks. In addition, in order for the clay not to crack during firing and to have the necessary strength, there must be a certain amount of sand. Usually, pure clay is chosen for brick production, and sand is added artificially. The best clay is considered to be one that gives a linear shrinkage of 6-8%.

An analysis of bricks from ancient Russian monuments showed that throughout the 11th century, kaolin clay was used for bricks, which sometimes had to be transported from afar. Bricks made from such clay are usually not red, but pink, fawn or light yellow. By the end of the 11th century, other types of clay also began to be used. In the 12th century, local clay was already widely used to make bricks. Moreover, the variety of clays in the bricks of one monument is a rare phenomenon.

Molding

The brought clay was kneaded in pits. After this, the molding of the raw materials began. We can to a certain extent judge the molding system from the traces preserved on the ancient Russian bricks themselves. Apparently, the clay was stuffed into a wooden frame mold, and then the excess was cut off with a wooden knife (rule) to the level of the top edge of the frame. Traces of such molding are clearly visible on many bricks. The top surface of the bricks is usually smooth and often has light scratches along the long axis - evidence of sliding rule. The bottom surface of the bricks is usually slightly rough - this is the imprint of the backing board that lay on the molding table. There are raised marks at the ends of the bricks. These signs, as a rule, are made clearly and are not blurred. If the shape for them was cut out in the side wall of the frame, the absence of blurred marks indicates that the frames were detachable. However, sometimes bricks have a slight curve, and the smooth (upper) side is always concave. Obviously, such curvature could occur when the raw material was knocked down from the frame, which is only possible with a permanent frame. When drying, the raw materials were first laid flat, and then turned on their edges, after which they were placed in stacks or banquets. The drying process lasted 10-14 days, but in unfavorable weather conditions it lasted for a month.

The molding of bricks was not carried out all year round, but only during the construction season from approximately May 20 to September 1, that is, it included about 90-100 working days. It is most likely that the bricks needed to build a small temple were prepared in one season, but for large buildings it may have been necessary to make them two or even three seasons in a row.

Kilns

Reconstruction, at least in the most general terms, of the process of functioning of brick kilns allows us to make an approximate calculation of their productivity. As you know, when installing bricks on an edge, there are free spaces between them so that hot gases can cover the raw material from all sides, so approximately 400-500 pieces could be placed in one row in the oven. In terms of height, in brick kilns in the 19th century it was recommended to lay no more than 25 rows of adobes, and for the most part - much less, only 16-18 rows. Thin bricks of the 12th century - plinth - were much easier to deform, and there is no doubt that these bricks could not be laid in many rows, like lumber. If we assume that the kiln was loaded with plinth to a height of 10 rows, then it turns out that up to 4-5 thousand bricks could be fired in the kiln at the same time. The operating season of the furnaces could last somewhat longer than the season of molding raw materials - up to 150 working days. Considering that the kiln operating cycle was approximately 2.5 weeks, we can assume that each kiln was used 8-10 times per season and could thus produce up to 50 thousand bricks. The number of bricks needed to build a sufficiently large temple (for example, the Cathedral on Protoka in Smolensk) is slightly less than 1 million pieces. And since during firing there was a lot of waste, the approximate quantity can be considered 1200 thousand pieces. Consequently, in order to ensure the construction of a medium-sized temple, at least 10 furnaces had to work simultaneously for two seasons.

Signs on bricks

There are signs on many ancient Russian plinth bricks. Their classification was proposed by I.M. Khozerov. According to his terminology, all convex images (both on the ends and on the bedded side of bricks) are called signs, and images pressed in with a stamp are called stamps. In addition to this classification, L. A. Belyaev proposed introducing the term “marks” to designate marks drawn with a finger or some other tool on the bedded side of the brick before firing. All these signs are different not only in design and execution technique, but also in the breadth of their distribution in various construction centers of Rus'. Moreover, as it turned out, they are different in purpose.

Brick range

The assortment of bricks from ancient Russian monuments, that is, the set of types and shapes of bricks, as well as the percentage of types, have been studied extremely poorly. It is difficult to do this in surviving monuments, because it is not always possible to measure the bricks in the masonry. In those cases when they are revealed by excavations, the set of types of bricks and their percentage do not always correspond to what took place in the entire building before its destruction. Often, during the process of clearing the area, the remains of the collapsed upper parts of the building were taken away somewhere. Therefore, in excavations, some types of bricks, which were used mainly in the upper parts of the structure, may sometimes not be found at all, not to mention the fact that the quantitative ratio of the different types of bricks found may be completely random.

As far as can be judged from the available fragmentary data, the set of bricks of the Church of the Tithes included mainly rectangular specimens. The most common size was 30 x 35 cm with a thickness of 2.5 cm, but both narrower bricks (24 x 35 cm) and square ones (31 x 31 cm) were also found. Narrow half bricks, 15-16 cm wide, were also used. In addition, bricks with semicircular and triangular ends, as well as slightly trapezoidal ones, were found in small quantities. An analysis of the assortment of bricks from Smolensk architectural monuments of the 12th century showed that here in all monuments ordinary rectangular bricks make up at least 70% of the total, in addition, up to 20% of the bricks are represented by narrow rectangular specimens and only about 10% are patterned bricks of various types.

Source: Rappoport P.A. Construction production of Ancient Rus' (X–XIII centuries)