A short radio interview on national Dutch radio2

Daniel Mayer [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]

(Sorry folks, the interview was in Dutch) On Sunday 11 August 2019 I was interviewed for radio show Bureau Kijkindevegte in response to the following question from a listener: How would a sculptor correct mistakes made during carving in stone? A short interview about how to approach the carving of a stone sculpture. More about this question can be found in the following article: …'Never hit that nose off?'?..↑

Beeldhouwerijblog.nl is the blog of Koen van Velzen, sculptor in stone and bronze. Look up my website as well: beeldhouwerijvanvelzen.nl

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Two stolen facade reliefs: a head and a spoonbill

My comeback on this blog!

I've recently had many different projects in progress and have just not gotten round to post any messages about them on this blog. But, fortunately we still have the pictures, as the businessman said when he saw his million dollar yacht sinking. This project has been an interesting challenge in between all the ornamental work. The job on hand was about two facade reliefs of a spoonbill and buddha head from Haarlem.

The original stone ornaments came from the façade of the Lutheran Orphan's and Old Men's Home, which was built in 1906. After the demolition of this home, the stones were reused in the garden wall of the Vitae Vesper Elderly Nursing Home that in 2015 was demolished again itself. An apartment building was constructed on this site and the reliefs remained behind, discarded and orphaned. The Lutheran Church Council wanted to provide these ornaments a final resting place in their garden wall between Frans Loenenhofje and the Lutheran Church in Haarlem.

A stolen spoonbill, pelican and buddha head

-click on the photo for the article-

The seven facade reliefs were removed from the original garden wall and kept separate. But three of those reliefs, of a pelican, a spoonbill and a Buddha head, were stolen from the construction site. Fortunately, the pelican was found again three days later. Apparently there is a market for stolen ornaments.

Stylized

The carvings are quite stylized and I thought for a minute that they were made in the Art Deco-style. But Art Deco only started from the 1920s, so although around 1906 there was already a stylization going on, it was not yet Art Deco.

The emphasis must have been on their decorative function, because I can't imagine what relation a heron and a Buddha head should have to a Lutheran orphanage. Or an Old Men's Home, for that matter. As the article mentions they were carved around 1905 by sculptor Tjipke Visser from Bergen, North-Holland. He made seven of those, a Buddha head, a head of a native American woman, two feline heads, an ibex, and a pelican and spoonbill. The spoonbill and the pelican are placed on opposite sides of an existing memorial in the garden wall of the Lutheran Church. The other reliefs got a place further down the wall.

We currently have a lot of work in progress at the same time. I just couldn't get it all finished on time alone, so I was glad Jelle took on the carving of the head while I was busy making a blue statue from sodalite in the meantime. Some time later I had time to tackle the carving of the spoonbill. We both followed the same procedure, so my approach below was the same for Jelle's sandstone head. I had ordered two blocks of Bentheimer sandstone to the right size, so we could get started right away.

Modeling and copying

Two new reliefs ready on the pallet

I had thought about carving this spoonbill straight out of the block, but that is not the best way to address it if the customer wants an exact copy. I had received a lot of pictures of the old reliefs via email, along with a number of measurements that were carried out on the counterparts that were preserved. This proved essential in the reconstruction: from these measurements and the pictures I was able to model a similar looking spoonbill in clay. Fortunately, there were pictures from three sides, from when the bird was still in its last garden wall. Once the clay model was to my satisfaction, I could start carving a copy in stone. Small details like feathers in the wings I had left out for the time being.

I traced the contours of the spoonbill onto a piece of cardboard, so I could transfer them onto the stone. After I'd carved away the stone outside the contours, I could transcribe the other sizes quite simply with a compass. In such a case, I usually put the two pieces tightly together. That way, I can transfer most of the width measurements one by one, without adjusting my compass. I've once made a video and a blog post about that. Once most measurements were in place and the rough shapes were carved, only the finish carving of the spoonbill needed to be done. The method of working from a clay model first is called the Indirect Carving Method. Read more about this method in this blog post↑.

Slideshow

-Click on a picture for the enlarged view-

The facade reliefs can be seen in the garden of the Lutheran Church, Witte Herenstraat 22 in Haarlem.

Beeldhouwerijblog.nl is the blog of Koen van Velzen, sculptor in stone and bronze. Look up my website as well: beeldhouwerijvanvelzen.nl

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What will save the Notre Dame? (2)

-read part 1 of this article here-

A very short time frame (2)

So President Macron has announced that the cathedral should be rebuilt in five years. He has appointed a French general to run the whole operation and there has also been announced that there will be a competition for a new spire. I guess it will become something made of steel and glass, with a modern slightly pyramid-like shape… oh wait, where have I seen something like that before?

All very remarkable. A number of well-informed decisions to be taken are pushed through quickly without discussion or consultation, and deploying the military renders the freedom to bypass a lot of rules. For yes, there will be needed a huge flow of materials (for the roof alone, more than 1300 thick straight oak trees are needed, and wherever would you get these from on such short notice? Fortunately British estates have already pledged to gift a few hundred of those.)

Logistical challenge

The advantage of management by a general is of course that he will be trained in military planning. He will have a thorough knowledge, or have at least access to people who can do it, of huge logistical flows on a scale that is uncommon in everyday life. I don't expect this general to be familiar with all the ins and outs of the restoration of a Gothic cathedral; for that there will be other people . He will be the person to take care of the basic conditions.

There are also huge amounts of new stone to be quarried, which will have to be processed in many different places and all brought to the cathedral at the right time. Luckily it's the right on the banks of the Seine, so just as in previous centuries, the material can be supplied over the water, so the city won't become clogged with trucks. Of course they'll need a jetty for unloading with a crane system and a large storing facility, but the Dutch among the readers know only too well that you can make that space yourself.

France has many quarries that supplied stone for the construction of churches in the past. There is a huge variety of natural stone, from granite, basaltic lava and hundreds of types of limestone to sandstone and gneiss. But not every stone, and not even all stone layers in the best quarries, are suited for church construction. Add to that the fact that currently many quarries have a relatively low production or even lie dormant, it becomes clear that a lot of them will have to be scaled up. Suppose a quarry has excellent material, but there is still quite a thick layer around it of lesser material. It will take some time before this quarry can supply the right material.

And that's not even mentioning the wooden roof, the roofing material, all the windows, all of the sculptures in bronze and stone, all of the ornaments, and where to get all the professionals from. And how they all get there.

The roof of a gothic church

cross-sectional view of the buttresses and flying buttresses

What has been lost now? Most striking is the disappearance of the wooden roof and the central spire. Now the roof of a Gothic church consists of two parts. First there is the stone vault which you can see from the inside, and this is covered by a wooden roof construction that carries the slate or, as in the case of the Notre Dame, the green copper roofing.

Imagine you open a book and put it upside down, like a roof, upon the table, with its pages to the inside. The book will want to sag outward and lie down flat, unless you stop that with your fingers to the sides. It works similar with such a roof: unless you provide back pressure to the sides or add a tensioning bar through the middle, it will want to lie flat. Since no tension rafters were used in the Gothic, but pointed arches instead, the outward pressure had to be taken care of from the outside. In the past, this was solved by building meters thick walls, which made large buildings very dark inside. The genius of the Gothic builders is that they designed open structures that supported the walls from the outside: the buttresses and flying buttresses. The walls therefore don't need to be massive anymore, and allow for huge windows.

At Notre Dame all 1300 wooden rafter beams of the roof have disappeared, and the underlying stone vault below has partly collapsed. A vault is a set of pointed arches that remain in place under their own weight, thanks to that pressure from the outside. The (triangular) spaces between said pointed arches is filled with masonry, so you end up with a stone roof: the vault. If you want to bring back the lost parts of the vaults of Notre Dame again, you'll need to put it back stone by stone. It is a self-supporting construction,, so during the build a heavy wooden support will have to carry the load: the so-called forms.

Once the vaults have been restored, the rafters can be built up again. This can be done with green wood if necessary; that has happened in the past, only one must take the shrinkage into account. I do not know if they do it like that nowadays as well or prefer to use dried oak. I have no knowledge of this work, but it is certainly a huge job to tailor all the wood joints and put them all together on site. Not even mentioning the wooden, lead-lined spire designed by Viollet-le-Duc.

The windows of Notre Dame. Photo by Lionel Allorge – CC BY-SA 3.0, Wikimedia Commons

The windows of a Gothic church

Tracery on the Chimera Gallery of Notre Dame. Photo by Parsifall – Own work, CC BY-SA 4.0, Wikimedia Commons

In the Middle Ages there was no technique yet to create large glass surfaces. Small panes of glass were made by turning round discs, and then cut to size. To put together all these loose pieces they were encased in lead profiles: hence glass-in-lead: stained glass windows. But don't be mistaken: glass art was at a very high level, both technically and artistically. The large glass surfaces were used to depict colourful scenes of biblical stories and saints. These windows have a wrought iron frame and an often wrought iron cross bar: a tension rod which should give support across the middle of the window , so that the window doesn't flex under wind pressure, and becomes one rigid unit.

The window's frame is made up of profiled natural stone. In fact, the whole window is a combination of stone, iron and glass: long slender stone ribs (bar tracery) divide the window into high vertical sections. At the top of the window, these join together into an ornate stone frame, the tracery, which has many creative shapes. Between the vertical bracing and the stone tracery at the top, the lead frames of the glasspanes are set into the stone notches..

It will be clear that a Gothic window is also very vulnerable. It is for many a wonder that the crown jewel of Notre Dame, its large rose window on the entrance side, has been preserved. Usually, the windows will be completely disassembled during thorough church restorations: all the glass panes are taken out by the glazier, cleaned up, repaired, and set in new lead frames. Often the stone vertical dividers will also be replaced and sometimes even the tracery at the top is copied into new stone, when the stone has deteriorated too much. Also, the iron bridge rods are removed, because they tend to corrode and crack the surrounding masonry. They are usually replaced by new bronze bars. Then often the remaining iron work is then mostly carried out in bronze or stainless steel.

Finally, everything is brought back. I've seen in many churches that the glazier also inserts panes of thick flat glass to the outside, to protect the stained glass and insulate it. However, a stained-glass window is never airtight, so it is extremely important that this front glass can breathe, to prevent accumulation of moisture behind it.

Now Notre Dame has quite a backlog in restoration. So if they want to do this properly, they'll really need to take on all of its windows. By the dozens. Where do you get all these glaziers from? And expert restoration contractors to remove the stone and iron work?

The drainage of a gothic church

gargoyle of the St. John's Cathedral in Den Bosch, copy new sandstone

Traditionally cathedrals have no modern downspouts. The water would have flushed off the roof into a wide stone gutter at the bottom of the roof, often behind a railing so that one could safely walk through the gutter. Later, many of those gutters have been lined with lead to prevent leakage.. Out of these gutters, water had to be carried far away from the walls. For that, there were two solutions: either it ran directly from the chute to the outside, or it was fed further out via a gutter on top of the flying buttresses. The end of the water outlet stood out from the walls for some distance and was often decorated with a monster head: behold the gargoyles. They spat the water out from the walls when it rained hard. Later on, often downspouts were still added, and the gargoyles just remained as a decorative element.

Often a church was topped with roof slate tiles: these lasted for a long time, and water was easily shed (from a slate roof, as is said). But Notre Dame had a beautiful copper roof, that was patinated green. But even a copper roof has a finite life expectancy, and I assume that roof was in need of a thorough inspection as well. Now no longer needed; a completely new roof, roof joists, and partly even vault will be needed.

Natural stone

Baldakijn voor de Sint-Janskathedraal in 's-Hertogenbosch in Udelfanger zandsteen

Canopy for the St. John's Cathedral in 's-Hertogenbosch in Udelfanger sandstone

A Gothic church is mainly built from stone. In the Netherlands, often the core of the walls are made out of brick, with a skin of natural stone blocks. But in France, where so much stone is available, many churches are constructed entirely of natural stone. In gothic architecture, practical construction and decoration go hand-in-hand inseparably with each other. Walls have moldings, where often leaf motifs are carved into, buttresses crowned with high pinnacles which are richly decorated with small crockets, flying buttresses have large leaf shaped ornaments, and everywhere you can see gargoyles, statues of saints, angels, reliefs and ornate portals. As described above, even the window frames are masterpieces of ingenious design in stone.

If in such a large church a hot fire is raging, the stone will become strongly heated. After a long heating with temperatures above 900 degrees Celsius, limestone disintegrates into calcium oxide (quicklime) and CO2. Although the fire at Notre Dame has not everywhere been so hot, it should be clear that the surrounding stonework sufferd severe damage and will partly have to be replaced. The stone in any case is not compact or reliable anymore. In addition, the church also suffered water damage and therefore will be at risk from fungus, and salt efflorescence corrosion in the anchorings, by which the anchors will expand and will destroy the stone later on. Finally, a lot of the stonework has been suffering so much from centuries of weather influences that many parts will have to be replaced.

Professionals needed

Stonemasonry blocks are essentially of an accumulation of geometric shapes. In exceptional cases I sometimes carve some parts of that as well.

For the restoration of such an extensive damage, hundreds of tons of processed stone will heave to be provided. Profiled blocks, blocks which only need a finishing chiseling stroke, sculptural parts, ornamental work, canopies, finials, and so on. The point is, it would take a few months for a stonemason to carve an intricate canopy. What do you do when you need to make hundreds of such blocks? France has far from enough masons who are doing this work at this moment. In addition there are even less highly specialized stonemasons, who can also make the most intricate work.

I expect that much of the work has to be contracted abroad. In France, the workload fell sharply for the stonecarvers by shrinking budgets for restoration. Less work means less stonemasons, it's as simple as that. Likewise, in the Netherlands a veritable bloodletting has taken place among stonemasons since about 2010, when several major restoration projects ended and companies had to let people go because of the crisis and the reduced number of projects. Older stonemasons have also stopped and never been replaced more. And in other countries that has taken place to a greater or lesser extent as well. I myself have been unemployed from 2010 to 2013 and had little work after that, until things finally got better in 2015. If there is such a gap between projects, many professionals will not return to their stonemasonry job.

tiny but very also large ornaments

Now I'm not a stonemason but a restoration sculptor. A restoration stonemason makes all the work that can be scribed with templates and can be drawn with construction lines. A sculptor makes the work that begins where the stonemason stops: ornaments and statues. Of these people, there are even less skilled craftsmen to be found. As far as I know, my three colleagues and I are the only ones still making sculptural work full time for churches and castles in Netherlands. In other countries, there are not many more of those. The French will need each skilled craftsman they can find, to complete this work so quickly.

Digitization of the process

picture of Thomas Aquinas to St. John's Cathedral in 's-hertogenbosch, currently in progress

Now time has not stood still since the Middle Ages. The computer age made its entry, even in traditional restoration. Already, all major stone processing plants own large CNC machines that can perform completely computer controlled cutting and milling. There are big five-or seven-axis milling robots which, with sawblades and routers that they can pick themselves completely unsupervised, can mill an entire sculpture from a block of stone. It seems like the solution. But it is obviously not all so simple. These robots first need prompts. Suppose, I want to copy an existing sculpture. Then I will have to scan the sculpture and enter that information into the computer and edit it into a usable virtual 3D image. Next, the scan should be checked for imperfections and those will have to be removed. Finally, a set of tasks will have to be assigned to the machine, the steps along which the robot can start milling out the sculpture from coarse to fine. In sculptures, or in blocks that are unique, this sequence needs to be repeated for every single block or sculpture. And then the stone block must still be loaded onto the machine and calibrated.

After milling, there are still a lot of details that the milling robot could not finish. It sure saves a lot of work for a sculptor, but here too, the hand of the artisan will still be indispensable. Indeed, unskilled finishing of such a sculpture can still totally ruin it. Stonemasonry blocks can be addressed that way as well, but there always comes a point where it is much faster and cheaper to have the final steps done manually by a skilled craftsman, than letting the robot slog on for days with a needle point endmill. And sometimes the machine can simply just not reach every nook and cranny, where a stone chisel can. In short, the skilled craftsman will still be necessary. And the main argument is that everything looks as dead as a doornail when it's all drawn with the computer and milled with the robot. "It is the hand of the craftsman that has to bring it to life', said a stonemason last all.

-Read more in Part Three: what are the possibilities, where lie the opportunities, what is the future and what will be the rescue of the Notre Dame?-

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Will the computer become the rescue for the Notre Dame? (1)

A disaster with far-reaching consequences

fire Notre Dame

photo by Wandrille de Préville – Own work, CC BY-SA 4.0, Wikimedia Commons

After some time, this will be old news already, but for now, this remains fresh in everyone's memory: a huge fire made the roof of Notre Dame in Paris collapse, on 15 april 2019. During the current restoration a fire broke out somewhere around the base of the spire, which, along with the rest of the roof, burned down and partly fell on the scaffold, and partly on the vault beneath. Part of the ceiling collapsed. All technical terms which I will explain later on. It surprised me how much I was shocked by the first television pictures of the burning cathedral. It is again clear that this is not just any French church somewhere , but an iconic place that belongs to the heritage of the world. Yet it is strange that the fire in this building evokes more emotions than a war or a famine on television. It's ultimately only a material object that was made for mankind. Is the human being then not more important?

A very short time frame (1)

Notre Dame before 2019

Notre Dame before 2019. Photo by Daniel Vorndran / DXR, CC BY-SA 3.0, Wikimedia Commons

French President Macron announced the next day already that the church will be rebuilt, and even within a period of five years. That's quite a bold statement: for example, for just the Utrecht Dom tower there are also scheduled five years of restoration, and that is in a lot better condition than the much larger Notre Dame. I think that Macron on the one hand could not estimate how very much work this restoration would be, but he must have also thought: "Better aim high and closely miss the target, then target too low and create a lingering eyesore.’ I suspect that most people know how much work has been put into building these cathedrals; often hundreds of years had passed before a cathedral finally was 'finished’ , or something like it.

From a way too tight budget to a huge budget

Now Notre Dame was under restoration at the time of the fire. The whole church needed to be restored, but there was not enough money. At the time of the fire the central tower (the spire) was being restored for 6,8 million euros. Notre Dame is one of the many thousands of monuments that France can boast of, and they all have to share the funding with numerous other candidates which are in equally bad shape, or worse. There also was a lot of maintenance and a first estimate was that a restoration would cost about 150 million euros. That still seems like a relatively low estimate: for the much smaller St. Eusebius's Church in Arnhem (the Netherlands) some 27 million euros were needed (though at first it was thought that 96 million was needed). After the fire in Paris, suddenly a floodwave in grants came forth and the counter is already at over a billion. You'd think that it should be about enough to do the job.

Three restorations in one

Notre Dame after the fire

After the fire. By Louis H. for G. – Own work, CC BY-SA 4.0, Wikimedia Commons

But in fact it's not just one restoration here, but three. Firstly, Notre Dame was hard in need of restoration already. In such a restoration usually especially the roof, the windows and its natural stone are tackled. The problems will then lie with the weathered roofing, rotten wood, worn glass-glass, and the replacement of rusting iron parts Window, and weathered stone parts, broken natural stone and missing parts. Often, the natural stone was also originally mounted with iron pins, which started to expand because of rusting , causing damage to the stonework surrounding it.

Secondly, because of the fire many parts have been lost. The roof has collapsed, a part of the vaulted ceiling has fallen down, the wooden central tower is gone, etc.. That will have to be brought back.

Thirdly, the fire has caused damages to lots of other parts. Stones that have been exposed to a hot fire for a long time can turn to dust on contact. There will also be water damage, and there will be parts that still seem usable but on closer inspection will have to be replaced anyway.

The architect

Such an extensive restoration requires good management. Especially with such a huge budget there will be a lot of people who get dollar signs in their eyes and hope to snatch a handful from the big pot. In the olden days, the cathedral building would have been led by a master builder. Someone who had gone through the whole training of stonemason and sculptor to architect, and knew all the ins and outs. He knew his materials, knew all of the required quality and had enough authority to manage everything smoothly.

It is sometimes said that in any commission three variables apply, and that you can only have two at once: fast, good and cheap. With so much time pressure on it, the last variable already died, and I fear that if not controlled tightly, quality too will dearly suffer under the haste. Menawhile, Notre Dame stands out as a prime example of the extremely high quality of the 19th-century restoration wave.

Viollet-le-Duc

In 1844 the cathedral was about to collapse. A comprehensive restoration plan was led by the then young architect Eugène Viollet-le-Duc. During that restoration many details were added to the church, which had have never been there before, such as the chimaeras on the balustrades of the two towers. Later critics this would probably like this to be reverted to a stage with more medieval elements, but it should be said that both technically and artistically that restoration was of very high level. Said restoration work, plus the writings of Viollet-le-Duc, have inaugurated in many countries a revival of Gothic architecture: the Gothic Revival. In the Netherlands it was mainly Viollet-le-Ducs admirer Pierre Cuypers that shaped the Gothic Revival. So with this legacy Notre Dame was both burdenend and enriched. It sets the baseline for the quality of the current restoration. You can not put a load of clumsy and inept modern work between the delicate neogothic ornamentry without seriously compromising the church. The task at hand is to do everything to approach that quality and that of the original Gothic work. It will be the job of the restoration architect to maintain a high quality in this.

Mapping it all out

St. John's cathedral, ‘s-Hertogenbosch.
by Zairon – Own work, CC BY-SA 4.0, Wikimedia Commons

The first task will be to chart every detail. What is still left, what is damaged, what should be replaced? From 1999 to 2010 I participated in the last major restoration of the St. John's Cathedral in 's-Hertogenbosch (and afterwards in smaller restoration phases). In such a restoration each facade, every window, each and every buttress flying buttress receives a number, and within those main components each piece of stone regains its own sequential number. Each block is put on a drawing and of each block is known what should be done with it: keep it, replace it or repair it. And that's just the chapter stonework! It may be clear that this requires some tremendous planning. At St. John's Cathedral, since the 90s digital mapping of each facade has been applied. Already in those years, the stone blocks were drawn in the computer in 3D CAD. A good working model and tight schedule should provide the guidance for all labor- and materials flows in and around the church.

Here, the computer can take a first share of the burden: by digitally scanning facades, the recorded data of the inspection can be linked to a database with all necessary data. Details like materials, state of the material, location, dimensions, sequential number and many other things can be stored for each component in the database.

Read more in Part 2 , including the construction of a gothic church, logistical bottlenecks, craftsmen, and more..,

Beeldhouwerijblog.nl is the blog of Koen van Velzen, sculptor in stone and bronze. Look up my website as well: beeldhouwerijvanvelzen.nl

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Which diamond chainsaw for which job?


My diamond chainsaw

I recently cut up a blue block of sodalite with my diamond chainsaw. Because it's quite an expensive material, I could save quite a large chunk by this method. If I'd made this sculpture in the normal way with the angle grinder, lump hammer and point chisel, I would have had some wheelbarrows full of expensive rubble for the dumpster. So in this case my chainsaw came in handy. But I actually rarely cut up or spalt large stone blocks. I actually bought this saw to remove blocks from historic buildings, or to cut loose heavily anchored statues from their foundation.

The diamond saw I chose in 2015 chose was a Cardi Coccodrillo35. But what types are there actually, what kind of job do you use them for, and which one is the best for which job?

Petrol engines

rough block of stone for Aachen Cathedral. Made a piercing cut with the diamond chainsaw

deep cuts in tight corners

The first type diamond chain saw for stone and concrete was made by the American company ICS. The older types ran on an extra greasy oil mixture, were heavy and noisy, and often choked because of a wet air filter, caused by the water spray thrown up by the chain. I hope that they have solved this now. ICS has also developed the first diamond chain, and now makes it for a lot of other manufacturers as well. ICS has several petrol versions on offer and make different kinds of chains.

Then also Husqvarna came with their own machine. They obviously have been making gasoline engines for chain saws and also for power cutters since a long time , so it fitted in well with their own range of machines. I know no further details. The price is around 3400 euros.

So their competitor Stihl could of course not lag behind. They have also developed their own version, plus their own chain with twice as many diamond bits on it.

Hydraulically driven

Now a gasoline engine makes a lot of noise and stench, and the torque at low revs is not great. That's why ICS soon developed a hydraulically powered version in the beginning, in three types. Hydraulic power is supplied by a separate hydraulic drive. This hydrostation of course also needs power supply, and this may be either via a gasoline engine (yet again noise and stench) or with an electric motor on 400 Volts (and then you'll need a 400 Volt power supply). The oil pressure goes to the chainsaw through two thick heavy hydraulic ducts. These are quite rigid and make the operation very difficult because they continually work against the operator.

Electric chainsaws

Then since the last few years there are also electric diamond chainsaws. I happen to own the machine shown above, the Cardi Coccodrillo35, by the Italian brand that also makes diamond drills and wall saws. It works on 230 volts at 3420 Watt.

But the German brand Dr. Schulze (if it says Herr Doktor in front of it, then it must be good!) has created a competitor to it that runs on both 230 Volt and on 400 volt. For the latter, you'll need a separate frequency converter, but then it suddenly consumes 6500 Watt, so it's a lot stronger on 3-phase power. Dr. Schulze uses the same motor for both their cutter and their ring saw as well. It is striking that this machine also has a kind of quick-tensioning knob, and a handle that can be adjusted in a variety of positions. Electric diamond chainsaws are a lot quieter, but not necessarily lighter than gasoline versions.

Pneumatic concrete chainsaw

For applications where sparks are absolutely undesirable because of fire hazard, an air powered version is also available. ICS provides one of those, for use in places where for example many utility lines are running.

Advantages and- disadvantages of the various types

Strong and light

sculptor Koen van Velzen cutting the statue of Moses from Lambertus church in Veghel with a concrete chainsaw / diamond chainsaw

cutting statues free with the chainsaw

I do not pretend that I know all about the different types of diamond chainsaw. I worked in the past with hydraulic chainsaws from ICS, with older petrol versions from ICS which kept choking and were very noisy and smelly, and now with my own 230Volt saw. But in short: gasoline saws are very flexible to use because they only require a water supply. This can already be done with a tank and a pump, though the pump will need to be powered by a generator or gasoline motor. It gets a lot easier if a water supply is simply available. Drawback therefore is their noise and stench. For the latter, you can adjust the fuel, that makes a bit of a difference already. But if, just a when I was working in Nijmegen at the Stevens Church, you need to cut for hours on end in a densely populated area, then it just wouldn't be right to start chainsawing right in the middle of city centre. Stihl would be my choice if I ever wanted a gasoline powered saw, because I've worked a lot with Stihl (chainsaw for wood, hedge trimmers and brushcutters), and was impressed by their quality. In addition, it's also fairly lightweight.

Much power and deep cutting

The hydraulic version is already a lot quieter. You can hear it clearly, but it's not deafening. The hydraulic power unit on gasoline makes a bit more noise. This machine is actually particularly suited to work in a well-organized construction site. You can cut very deep with the hydraulic version and have a lot of torque, but with that big power pack for the oil pressure it's just not as easy to move. Especially if you work on 3-phase power. I've always hated these machines because those heavy hydraulic hoses make using them so exhausting. I was always searching for places that I could hang them up on with a length of rope or I had them slung over my shoulder. But it's a very reliable machine; not much to get damaged on it. It can take a beating and can even do its work under water just fine.

No sparks

I'm not familiar with the pneumatic version of the diamond chainsaw, but judging from all air powered equipment, it seems to me that these don't have much torque left at low rpms. Added to that, a large air consumption always leads to a cooling effect, So I wonder how this would work at lower ambient temperatures. Maybe then you'll need to have an air dryer as well. Plus, you'll need to rent a large diesel compressor. I expect this one would also make a pretty loud howling noise.

No odor and flexible

My electric version was the solution for me. It's obviously not silent, but generates much less noise than a petrol engine. You can't cut as fast as some gasoline- and hydraulic saws, because you've got less power. The version of Dr.. Schulze promises several options for chains and sword. However, an electric motor of 3500 Watts is no light thing, so it is as heavy or heavier than a gasoline engine.

Chains and quick release

At Stihl they have developed their own sword and chain, though I do hear that a chain with diamonds on each link is not always convenient: Sometimes the chain itself wears out faster than the diamonds do, so that would unecessarily raise the costs. For example if you're cutting sandstone or brick. That is why ICS is sporting various different chains, for example, for brick, fresh concrete, hard concrete, granite and an economic version.

Now a diamond chain stretches out really fast. While cutting, you're continually checking to ensure that the tension is still right. A too tight chain pulls the blade sideways and thus gets stuck in the kerf, and a too loose chain get unrailed and starts to 'wander about’ inside the kerf. It should hang loosely so that the links at the bottom of the blade just clear the rails. Once the engine starts pulling it will be just right. Tensioning is a tedious job: you always keep unscrewing the two nuts again that you just tightened up, then tightening a difficult to reach nut behind the chain and finally tightening the two lock nuts again . At Mito they have since found a solution: a quick release on top of the diamond chainsaw. This machine is by Chicago Diamond Supply and works on hydraulics, but I think there will be many more to follow suit soon.

Dr. Schulze has also something like that, as I think I noticed. Unfortunately no videos of how this thing works.

Applications for the diamond chainsaw

I use my diamond chain for cutting loose statues and stone blocks, in case I want to cut any deeper than the 7 cm from my angle grinder. In recent times I've done for example deep cuts in stone finials, cutting smaller some old tufa side flowers, cutting behind the back of Noah, and cutting Moses and Aaron free from their walls, and removing a pedestal.

In restoration these machines are used for removing large blocks from a facade with minimal damage to the surroundings. In construction they use it for all kinds of modifications to existing buildings, though large circular saws and wire saws are much in use there as well.

Table

Table of diamond chainsaws

-Click on the image for the file in pdf (Sorry, it's in Dutch only)-

Update 2 april 2019: Apparently it's all a lot cheaper if you go shopping in Germany (for example, the Cardi Coccodrillo costs € 1988,45 there, incl VAT, and they'll put in an extra chain!)

Beeldhouwerijblog.nl is the blog of Koen van Velzen, sculptor in stone and bronze. Look up my website as well: beeldhouwerijvanvelzen.nl

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Sculpture 'The Night’ for St. Eusebius Church Tower


Last phase of the tower

Work on the tower of St. Eusebius's Church is nearing completion. Actually, the sculptres of The Day and The Night are the last two pieces that the builders are urgently waiting for. So I think a deep sigh of relief must have come from the scaffolds of the church when I completed The Night this week. For the tower, and part of the church, need to be free of scaffolding when a commemoration of the Battle of Arnhem is held this autumn, looking back to, 75 years ago. But this sculpture was not the only thing that still needed to be done. I've been carving away for St. John's Cathedral in Den Bosch, for the the Utrecht cathedral, again for Saint John's Cathedral, and the flying buttress figurines for St. Eusebius' Church itself should be ready in time as well.

Day and Night

This corner sculpture is located at about 15 meters up and was originally carved in tuff by Eduard van Kuilenburg. She's part of a pair: there is a guy with a rooster, breaking his shackles and brandishing a mop (or should it represent a flaming torch?), and yes, this woman with a nest of owls too. The Day and The Night. This lascivious young lady is sitting with the left hand in her hair, on one knee, with a stick in her right hand. The purpose of the stick is not clear to me, or perhaps it should represent an extinguished candle. The owls represent nightlife, the rooster and the broken shackles stand for dawn. I suppose he's about to extinguish the torch and is not going to mop the floor, because he 's not carrying a bucket.

Presawing

This relief is the biggest block from this church we received in the yard in recent years: almost 1 cubic metre. Due to time constraints we decided to use the copying saw, but the block was so large that it couldn't even turn around on the turntable of the machine. I had to literally cut a number of corners to make it fit. These were however just those corners that ultimately will be embedded inside the masonry, so you won't see anything of it later on. This presawing is saving me days of measuring work, by enabling me to start carving by eye from quite early on. Plus it saves me a lot of rough carving and sawing with an angle grinder, freeing me from a lot of the hard work. I glued two stainless steel threaded rods M16 into the top of the new block, onto which I can screw a eye bolt for lifting, making the block easy to move. It may come in handy on the scaffolds later on as well for the restoration masons.

Little feet

The block of new Muschelkalk limestone of over 1800 kilos was provided by the Stonemasonry Firm, who also carved the profiles on it. Unfortunately, the stonemason in question was somewhat preactieve, which caused that I was short on material for the lady's toes. Added to that was that the original sculpture was a lady with a unique anatomy. Her knee was pointing straight forward, but her left foot was targeted towards the viewers at home. So I made a virtue of necessity and right away took the opportunity to give her left foot a somewhat more logical position. The right foot also missed a lot of stone, but I was still able to carve it nicely by putting it more back and in a bit flatter position. If you don't place the original right next to it, it will not stand out at all. It was an interesting challenge and I'm really pleased with how it turned out (See the slideshow below for pictures).

Nest of owls, finish

Near her right shoulder is an owl mother with her nest with two young. The chicks look endearing, with their surprised look.

I finished the entire sculpture with a wide tooth chisel, and then smoothened the body of the young lady with a coarse grater, leaving the chisel marks still barely visible, for a lively effect. Her hair and the owl's feathers I accented with the tooth chisel.

Sculpture The Night by Eduard Kuilsburg- new copy in Muschelkalk limestoneSculpture The Night by Eduard Kuilsburg- new copy in Muschelkalk limestone

Headless chicken

The sculpture of The Day was in a lot worse condition than The Night. The rooster and the man were both missing their heads , and the hand with the torch had disappeared as well. So I first needed to reconstruct those parts before I could start presawing. I modeled the neck and head of the rooster with plasticine and the hand was remade pretty quickly too. The tricky part was the position of the original hand, because in the only picture I had, the fingers were in an almost impossible position. But the head was more of a challenge. because this young man had quite a big head. I had glued a piece of hard PIR-foam onto his shoulders and from there I started looking for the right size, position and shape of the head.
I tried to see my progress by comparing my pictures with the original image. In the end Stide decided he would carve this one, so he has has been the one to make the finishing touches to the remodelling. See the gallery below for an impression.

Gallery -click on a thumbnail for the entire picture-

Beeldhouwerijblog.nl is the blog of Koen van Velzen, sculptor in stone and bronze. Look up my website as well: beeldhouwerijvanvelzen.nl

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the Supreme Commander-in-Chief (flying buttress figurine)

flying buttress figurine of Commandor in Chief by George vd Wagt. Copying into limestoneThe next flying buttress figurine is the topmost one of flying buttress no. 33. The statues on this flying buttress were carved in 1954 by George van der Wagt, and depict six crippled, blind and lame persons, after the Beatitudes from the Sermon on the Mount. At the top sits a male figure with a beard, in a blessing posture.

Mudra

flying buttress figurine of Spureme Commander-in-Chief (with Abhaya Mudra) by George vd Wagt. The copy in limestoneThis blessing posture is often depicted in Christian art, in particular in icons. I do not know if this posture has a specific name in Christian literature. I know it from the oriental yoga; where this hand gesture is called the Abhaya Mudra: meaning, "No fear'-hand gesture. It is meant to take all fear away from the blessed person. In the West, this gesture has a more general meaning of blessing.

Supreme Commander In Chief

The Beatitudes: old flying buttres figurine of Woman With Headache

The Beatitudes: old flying buttres figurine of Woman With Headache

It is not clear to me whom this figure should portray. It's mentioned as 'a prophet’ in the records of the restoration from 1954, but I think it was rather meant to depict God the Father, on his heavenly throne. Perhaps the sculptor meant that the people who suffer are blessed. Van der Wagt was apparently not religious. In a newspaper article from that time he explained that he did not know what the story of the Foolish and Wise Virgins was about. He borrowed a Bible and read the story, 'And that's why now there are women carrying cans of oil all over the church'. So I guess he that he didn't ascribe a higher meaning to this sculpture as much, but made it to complete the series. Perhaps this was also done at the request of the church council, or whoever chose the iconographic themes.

Beeldhouwerijblog.nl is the blog of Koen van Velzen, sculptor in stone and bronze. Look up my website as well: beeldhouwerijvanvelzen.nl

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and Twitter
and on YouTube

Flying buttress figurine: A Foolish Maiden


A foolish maiden

flying buttress statue from the Eusebius Church in Arnhem: a Foolish Maiden

the old tufa sculptur

Of the flying buttresses which we are now working on, each have their own theme. There are seven trumpet angels, people who represent the Beatitudes from the Sermon on the Mount, a group of Wise Maidens and this sculpture from the last arc depicts a Foolish Maiden.

Briefly, the story goes like this: …Read the whole article…

Thomas Aquinas (sandstone) for St. John's Cathedral

The statue of Thomas Aquinas

Thomas Aquinas: Here the statue is still in its niche of St John's Cathedral

St. John's cathedral

The major overhaul of St. John's cathedral is steadily continuing. Each year or maybe every two years, I'm not quite sure, one bay of the church is restored: 1 buttress and 1 window facade. This year I already did some work on two finial bases, a …Read the whole article…

Two griffins with a large shield

griffins with shield castle entrance plastiline maquetteThe next project has taken a very long time to get properly going. More than a year ago I received this request, and only now there is the peace and time to address this well. It is not a simple little project for doing between other things. …Read the whole article…