There is a lot of controversy online about the columns of St. Isaac's Cathedral. Many are very skeptical about the official version of the construction of St. Isaac's Cathedral by A. Montferrand and they are right. Not only is it technically impossible to make columns even now, in any case, at the moment, there is simply no corresponding technological base anywhere in the world. So there is still a mass of direct and indirect evidence of the existence of this cathedral earlier than the official dates for the construction of the cathedral. For example, here is a drawing by A. Bryullov in which we see our modern cathedral at 3/4. Only two small colonnades and other domes are missing. The most interesting thing is that inside St. Isaac's Cathedral, where 4 versions of St. Isaac's Church are presented in chronological order, this option is absent. It is understandable, because it does not fit into the required paradigm.
We will not go further into history, we will only touch on the technical side. It is quite remarkable because the cathedral is unique. What and how was done there.
Let's start with the columns. The main columns, which are made of granite and which weigh 114 (some source 117) tons. Now several versions of the manufacture of columns are being discussed, the disputes are not comic. Someone thinks that the columns were made by casting. Someone says that the columns are made of brick, sections or concrete and are simply plastered. In general, this is not a monolithic natural granite, since it is technologically impossible to make such columns with a chisel and by eye, and lathes for processing stone blocks weighing hundreds of tons cannot exist, especially in the 19th century.
Proponents of concrete technology cite as an example a handicraft handbook with this recipe:
They also give just such a picture with a certain frame made of boards of certain columns. This picture is applied to the Kazan Cathedral, but we are talking about technology in principle, and according to the supporters of concrete technology, this is how all the columns were cast, including the columns of St. Isaac's Cathedral.
Promotional video:
However, in this figure, it is not the formwork, as it is commonly thought, but only the strapping of the FINISHED column in order to fasten the scaffolding to it. Look carefully at the drawing again and you will see for yourself. The finished column is not cheap, any chip, any crack will mean either a replacement or a major repair of the column, at whose expense? And for this, from the risks of damage, an expensive column is simply closed, and the protective boards along the way have a bearing load as supports for scaffolding. You will not drill to the column?
Proponents of plaster suggest something like this technology.
And as proof here is such a photo from the Roman Pantheon. Like at that time there was a technology for the manufacture of plaster mixes repeating natural granite.
Now let's consider in detail the columns themselves and all versions.
Let's start with plaster technology. We need to start with the fact that in the examples of various photographs with plaster peeling off the columns, in the same Roman Pantheon, for example, we see only traces of restoration. Made "now", done carelessly, and that's why it gets honored. The material used is polymer. Now there are a lot of polymeric materials for various stones, they are used not only by restorers and builders, but also by finishers, designers and various other decorators. They make baths, kitchen countertops, vases, figurines, etc. Various technologies, from certain composites on a certain binding basis with granite chips to "liquid granite".
Even if we admit the fact of applying certain plaster compositions imitating granite, then a whole series of problems creeps out with a small train that will have to be solved.
The first problem is how to fix it. In modern construction, when layers of plaster are applied with an eye to durability, plaster mesh is ALWAYS used. Previously, the so-called shingles were also often used, this is a wooden crate, which in fact is also a variant of a certain grid. The mesh also implies some kind of rigid attachment to the base. This I mean that when "opening" certain layers of plaster, we would inevitably see some objects foreign from stone or plaster. However, in the case of Isaac's columns, we do not see them.
At the beginning of the article, I cited a quote from a handicraftsman's handbook, where it is written that a layer of plaster is applied with a thickness of 6 to 12 mm. And it is right. For the fraction of granite crumbs will not allow thinner, and if you make it thicker, then you need either a mesh, or it will all fall off very quickly. Even modern super-technological and super-sticky one-component plaster mixes do not allow the application of one layer thicker than 3-4 cm. If thicker, then in several stages (layers) or with rubble. Further. The multicomponent composition of the plaster mixture will inevitably imply its subsequent leveling, because it will never be possible to apply it in an even layer. Here's the next problem. The binder composition is difficult to match in terms of density and hardness with components (granite chips) of the plaster mixture. That is, if you use some mechanical objects,as modern plasterers do in the form of some spatulas and rules, some fractions will be pulled out. You can't do without it. This can be avoided only by using a high-speed cutting tool, like modern grinders. And then the next problem of a similar plan is how to polish it all. And how to fill inevitable cavities (voids) and cracks. In general, there are too many questions, the answers to which are very difficult to obtain.
Questions will be of a similar plan for the concrete version. We need to start with the fact that you need to pour concrete into the mold at one time. This is if you want to avoid reinforcement. According to this principle, for example, concrete rings for wells or blocks for foundations are cast. Large forms with the use of large volumes of concrete in portions in several stages are always cast with reinforcement.
Whether in the 19th century there was a possibility of one-time pouring 114 tons of the prepared mixture into a mold, I do not know, but it is very difficult to imagine how it might look, despite the fact that the concrete mixture must be in motion all the time, otherwise heavy fractions will quickly sink to the bottom. Now mixers and other rotating containers are used for this. And do not forget about the Alexandria column weighing 600 tons (10 railway tanks). The next inevitable problem in the concrete casting version will be the problem of caverns. They are now found on any concrete surface. Look at street telegraph poles, for example. So I photographed the closest one. He is covered in caverns.
It will be the same even if you use a smooth formwork, such as a film.
There will always be some air bubbles in the concrete mixture, in addition, heat is released during the crystallization process, which leads to the release of vapors, so there is almost nothing without it. Precisely almost, because a way to remove caverns was invented - this is a vibro-formwork (vibropress). That is, movable formwork. In this way, washbasins, bathtubs, countertops, vases, figurines, etc. are now cast … But these are all objects of relatively small size. I personally cannot imagine a vibrating formwork tens of meters high with a solution mass of a hundred tons.
And do not forget about all the problems inherent in plaster. For the cast mold will inevitably have to be brought to a condition - to level, grind, putty, polish, etc. Look, for example, at the repair of asphalt on our roads. Very revealing. The cut of asphalt is what we see just on the columns of Isakia. That is, the Isakia columns have traces of machining with a high-speed cutting tool.
Now let's move on to the columns themselves. The last photo is not accidental. It shows not only clear traces of machining (cutting) with a high-speed tool, but also shows how the restoration is now taking place. The problematic section of the column is removed, reinforcement is inserted and a certain composite polymer composition with granite chips is applied. Or a patch is inserted (pasted). The black color in this case is most likely some kind of primer or old glue. Then it is all grinded and polished.
The fact that the columns of Isaac are a natural stone can be proved by the following facts. First of all, the fact that not only the columns are made of such granite, but also all the foundations under the cathedral and the area around the cathedral. And even curbs. And in general, almost the floor of St. Petersburg is made of this granite. He is also on the forts, and he is also in Kronstadt. This is the so-called rapakivi.
Natural texture will be the next proof. Rapakivi is not distinguished by a beautiful pattern, unlike gray and black granites. Nevertheless, a certain texture, although not very pronounced, does exist. If you walk along the cathedral, you can see it here and there.
Here are the blocks of the base of the cathedral, we see a textured drawing (line).
And here we are carefully looking at the lower third of the near column. Distinct drawing. Now look at the next column, it has several streaks in the form of dark spots. In the right row on the third column in the center there is also a distinct pattern.
There is a drawing on this column below.
By the way, there are traces of fragments from bombs on it. There is a huge pothole at the top of the right column, I showed this place in close-up at the beginning of the article. Officially, this is from a fragment from a bomb during the Great Patriotic War, but this fact seems to me to be double-checked. Where did the bomb explode, despite the fact that there was only one large chip on one column, and some shrapnel from small fragments on the other? And they are directed towards each other. It turns out that the bomb exploded somewhere between the columns? But according to the official history, there was not a single direct hit in the cathedral during the war. If the explosion was far away, then it is not clear how the fragments flew - once, and what kind of bomb there was - two, so that at a height of 20 meters from a hundred-ton granite block, just a huge piece with a fragment.
By the way. This fact completely rejects both the version of the plaster, because it would fly off like a blanket in the first place, and the version into the segmented assembly of the column. If the column consisted of component parts, then from the impact of such a powerful force, cracks would inevitably go along the segments of the column. Transverse cracks. We also don't see them anywhere. However, there are many cracks in the columns. But they are all exclusively in the vertical plane. The explanation is generally simple. The cathedral has a drawdown in the center. There was a progressive drawdown in the 19th century, during its rebuilding by Montferrand. Moreover, not only did the center sag, but also the perimeter swelled, especially on the newly built two colonnades (small). Today, the difference in subsidence on the sides of the cathedral is up to 45 cm, the vertical deviation is 27 cm. Despite the fact that in the 20th century, the cathedral sank by only 5 mm. More on this.
Move on. Another column. On it, the texture pattern is clearly visible along the entire height.
Why do I pay so much attention to texture drawing. The fact is that it is impossible to artificially repeat it. No concrete technology, no plaster. We look at the center of this column.
Another column. And on this we will finish.
Let's move on to the cracks. They are almost all vertical. And this is understandable, because cracks are formed only at points of force. The impact force on the column is vertical, which means that only vertical cracks can go. Here, by the way, the crack goes through the texture pattern.
Some of the cracks are quite extensive and have already been restored.
But this crack is quite remarkable.
This is the only transverse crack there is. It is closed, that is, along the entire circumference. I have not decided on the conclusions, either this is a natural texture pattern, or it is a very good repair. If repairs, then we have a column consisting of 2 parts. Perhaps it was dropped and it shattered. If so, then the work is jewelry and the builders must be given their due. Although the whole cathedral is built in such a way that one can only marvel, so it is not very surprising.
Now to how flat the surfaces of the columns are in geometric terms. As it turned out, they are not very even. In view of the scale, this is not noticeable, but if you look closely at the luminous flux, then the curvature of the columns is very clearly visible. Pay attention to the border of light and shadow, especially at the top. She is wavy.
Then he brought it closer.
What is it? And why is that? For clarification, let's look at a different angle. In this perspective, we see that in the transverse plane the column has a certain pitch of dark and light spots. Like some segments. So they give the column a certain waviness. In sunny weather, this segmentation is well pronounced. Apparently it was this fact that formed the basis for the version in the segment composition of the columns with some subsequent plaster. But this is not the case.
This segment track is just a polishing machine track. The columns were not polished by hand, but by some mechanical method with rotation around the column. Namely around, from that and such a trace. Now I will not bother myself how exactly this was done and design a certain machine, I will simply designate it as a fact. We have traces of the tool rotating around the column. I will not discuss what kind of cutter attachments and polishing compounds were used in this case. This is secondary. I will repeat once again the photo with the textured pattern. the segments are also clearly visible in this photo.
Could these be traces of a lathe? Yes they can. Subsequent grinding and polishing could both smooth out the waviness, and vice versa, increase it. Fifty-fifty. And most likely both of them together. It is only unambiguous that the column is machined with a tool that has a stroke around the column. Or the column was rotating.
This completes part 1, in the second part we go inside the cathedral.
Read the continuation here.
Author: zodchi1
