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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Boulder and oak-tree and stone

A stone-tree for the group home

Today in Amersfoort, a new group home for people with a mild intellectual disability was inaugurated. I've lately been involved (pro deo) in a number of things in the new home, including the stone-tree and the boulder in the garden. Read here↑ an earlier post about the boulder.

The stone-tree was a special project for me, because it led me to undertake several things that I do not normally do. It's a long story, so let's start at the beginning!

The mad squire in 1661

boulder and oak- pulling the Amersfoort boulder, on an old print

Each Amersfoort resident knows the story of the mad squire and the Amersfoort boulder. Or, at least, he/she should know it. In short it goes like this: Squire Everard Meyster makes a walk on the Leusden moors with his study pals, and comes upon a huge boulder, sticking out of the ground. After some speculation about the origin of the boulder the squire is willing to bet that the boulder would be easy to move. He gets 400 Amersfoorters crazy enough that they willingly, and for promises of lots of beer and pretzels start to move the boulder of 7 tons and hoist it on a cart, and under loud cheering bring it into the city. A man lost his legs in the excitement, but that couldn't spoil the fun.

Then the stone was set on display at the Pig's Market. Later, the squire writes a mocking rhyme about the gullible Amersfoorters, and the boulder was buried out of shame. Only in 1903 the boulder was dug up again. Today, the boulder is still visible at the beginning of the Arnhem street. A stone's throw from the group home.

Real Amersfoort boulders

Amersfoorters have been nicknamed Boulder pullers ever since that day’ and the city is also called Boulder Town. So what was a more appropriate name for the future residents than The Boulder Club?

At one of the meetings of the Club every resident has painted their own stone. And these remained lying around in a basket somewhere in the house. A pity though, thought the central committee, and after some discussion an idea came up for a work of art, a tree with these stones as leaves. Boulder and Oak.

Whoever thought up what, I don't know anymore, but in the practical part, it ultimately came down to a collaboration between me and painter Sandra Nanning, who has made a lot of murals, and from trees as well. Sandra was going to paint a large tree in the stairwell, and I would attach the stones to stainless steel tree leaves.

Making tree leaves

I bought a sheet of stainless steel and cut out the shape of the leaves. After that, I made a hole in the middle, and a fold over its length. I tapped the leaf halves around a thick tube to get the leaf effect, and welded an long M8 nut on the rear side. Into that, I welded a threaded wire piece, with which I can fix the leaf into the wall. It is a somewhat cumbersome construction, but now every leaf has a nut into wihich I can screw a stone.

-Click on a picture for the slide show-

Each stone had to be pierced. And there were hard ones among them! Limestones I can drill without the hammer function, but a piece of granite can't be drilled with a hammer drill. It would break in half. So many of these stones I needed to patiently pierce with a diamond bit. 32 in all, so I had enough on my hands there.

A huge tree in the stairwell

boulder and oak-tree and stoneSandra then went to work on the back wall of the stairwell. She painted one big tree, from the ground floor up to the second floor continuously. It also runs out into the two side walls, so it stands with an imposing presence. At the bottom are the names of the initiators of the project, plus the architect and the owners of the property who have put so much work in.

On the first floor is a poem about a tree that was good at letting go. And on the top two floors are the stones of the residents, criss-cross all over, each on their own stainless steel tree leaf.

boulder and oak-tree and stone2

Should it be necessary, they can be screwed out again, and there are still four spots left for future residents.

The Tree in the Wood

The tree in the wood

in autumn let everything loose

He let go of it all and as he stood

he whispered softly:

'Letting go is paramount

boulder and oak, stone and tree3in life, to stand stronger and be sound ’poem on tree

 

 

 

 

Placement of the boulder with the house numbers

boulder and oak- boulder hoistedA week earlier at the same address, I installed the boulder that I recently carved the house numbers in . The boulder was put in the front yard, right next to the entrance. I had transported the nearly 500 kg heavy boulder in the back of my white little van. I could lift it out with an engine hoist I'd brought along in a trailer. After that, it was only a matter of laying planks and planting it into the garden.

boulder and oak-positioning of the boulder2

 

 

boulder and oak- boulder planted

Boulder and Oak

boulder and oak- planting the oak tree

This boulder was not the only thing that was planted; later that week a young oak tree (Quercus Robur) was also planted, in appreciation of the architect and the two developers. Because an oak can live for over 450 years here, we hope that both the group home and the oak will live a long and happy life.

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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The flying buttress of the seven sins

luchtboogbeelden 'De Zeven Zonden' old, arramged in the yard.

We, sculptors

A nice project is coming up soon! As you may know, for a few years now we've been working for St. Eusebius's Church in Arnhem (the Netherlands). Who are we? Well firstly myself of course, Koen van Velzen, restoration sculptor, pleased to meet you. I work with my colleagues Stide Vos, who rents the studio next to mine. And in the past year on this project, our newest addition Jelle Steendam has joined us. He works in my shop space, as an independent sculptor, in consultation with me, on various sculptures.

Seven Sins

flying buttress no. 32 of the Eusebius Church is finished and installed

meanwhile, the first flying buttress figurines of the second series are being installed

We have now completed eight flying buttresses, but there are still 7 more with sculptures on this church. That why I recently welcomed the next series of 7 figurines to my yard, for flying buttress no. 24. The theme of this arc is 'The Seven Sins’.

An interesting theme, that immediately evokes various images to me as a sculptor. For how do you imagine Pride, Rage, or Envy? This kind of thing is very interesting if like me you're a storyteller. Most people may not know me that way, but I love stories.

Fortunately, this series also showed an interesting challenge for the original sculptor. Because what we're about to do with it is copying them. No new designs this time. It's true, three of the statues are missing an arm, but otherwise they're very clear in what they portray.

Broken

The Seven Sins: Lust, a broken old statue of impregnated tuffThey came in, packed in wooden crates and wrapped in netting. The reason for this is a difficult issue, and it's not clear to me what exactly went wrong with these figurines, even after quite a number of discussions. In short: The sculptures of the Seven Sins were carved in tuff around 1955. In the 1990s they started to deteriorate, and to preserve them, they were sent for impregnation with acrylic resin, up to the core. Read here↑ more about this process. It's a good process, albeit fairly expensive, but with these sculptures, something has gone completely wrong. In one way or another they started to expand, and they still do. Lots of deep cracks appeared, and suddenly pieces began falling off. To avoid worse all figurines were quickly removed and stored in boxes. And even inside those boxes they continued to expand and break.

Gluing it all up again

luchtboogbeelden 'De Zeven Zonden' are being glued up by Jelle Steendam in the yard of Beeldhouwerij van Velzen

So the first thing Jelle started on, with my help, was unpacking and bonding of these figurines. The pieces are razor sharp but fit reasonably well. After all the unpacking and gluing we had seven well recognizable sculptures in a row. Next step is to reconstruct the missing parts on the basis of old photographs (so if you have any old photos of the Seven Sins, in particular, of Gluttony, Avarice or Vanity, I hope you'll mail them to me!).

I have been looking forward a lot to make something beautiful out of them again!

luchtboogbeelden 'De Zeven Zonden' old, arramged in the yard.

lust-envy-pride-gluttony-rage-avarice-vanity

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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Year review of 2018

Year review of 2018

It seemed nice to sum up this year of sculpting in some words and pictures. Not in chronological order, because my work sometimes jumps from one thing to another, for often suddenly urgent commissions come in between. I like it that way too, I love things being a bit unpredictable! But only when there's not too much pressure on things.

Finishing flying buttresses 4, 5, 6 and 7

Gallery -click on a photo to see it larger-

Last year I spent a long time making flying buttress figurines for the north side of St. Eusebius's Church in Arnhem. Early January that job was nearly done; I only had to make a Monk, a Bear, a man calling Noah, a Monkey and a Ark with animals to round it off. It was the last series of the four flying buttresses themed around Noah's Ark.

Calamities and Repairs

Amid heavy snowfall and storms, work went on as usual. I accounted for a severe frost period and just continued sawing. A part of the barn didn't feel the same way about it, and collapsed under the weight of a thick layer of wet snow. A few weeks later I narrowly escaped from a disaster, when in a torrential storm a sheet of asbestos was blown from the roof and landed right next to my finished flying buttress sculptures.

Part of my repair work consists of patching up damaged statues. For instance I had to repair a Faun with a Pan Flute and a statue of Thomas Aquinas in my shop this year.

Injury and recovery

Something I've not reported on this blog is that I've been incapacitated for quite some time by injuries earlier this year. I hear you think it would surely have come about because of my job. I do have quite the productivity and it is rather physical work. And at times there can be some pressure to finish it all in time. But it wasn't anything like that. First it was an accident when I cut open my thumb deep on a party tent that threatened to blow away. Just three stitches and two weeks later I was back at work again.

But it was not long before I was back home for some weeks. This time I had overstrained both my arms during removals (at temperatures around minus eight degrees Celsius). At least I now know how to recover from two tennis elbow quickly: not with all kinds of therapies, but by massaging the muscles in your forearm deeply for several times a day. This way, you'll relieve the tension from of the muscle and it will no longer pull so hard on your funny bone, let's put it this way. Learned on YouTube and experimentally tested myself.

Own work: Pan in porphyry

block of porphyry for plaster image of Pan

plaster sculpture of Pan with block of porphyry

After all these flying buttress figurines, I started enthusiastically on my own project: a Pan in porphyry. I had presawn it on my machine and had just begun carving it, but in spite of all the good intentions, I had to put it aside because of other urent projects.

Ornamental works: Aachen, Utrecht, Den Bosch

For all kinds of ornaments had arrived in the yard, which were to be made first. So this year I made finials and crockets for Aachen Cathedral, for the Cathedral of Utrecht, again for the Utrecht Dom, and for St John's Cathedral in Den Bosch. Some of them in collaboration with my colleagues. There was stonemasonry work to do. Even a newspaper article was written about it and a video was made.

Family Crests and griffins

Then there were two sandstone family crests which I made in between other stuff, one with an edge and one without edge, and I have been modelling away on a set of mirrored griffins. I hope to finish them next year.

Jelle, Jeffrey and Roel

Annual Review 2018

Wise Virgin with a Dove, copied by Jelle

With so much work it was not surprising that I could not keep up with it all by myself. Hence my collaboration with my colleagues and Serge and Stide. Even then, we were not able to finish it all in time. Also, I had long thought about someone to pass the craft on to, someone who wanted to become a restoration sculptor. But how do you get someone who fits the bill? Fortunately Jelle came to visit. Exactly at the right time. He has now been working with me for more than six months, to the satisfaction of both of us and doing excellent work!

Annual Review 2018

Jeffrey helps presawing

Then this summer I've had help from Jeffrey a few times, who came to help out with presawing on the machine, while at the same time my nephew Roel came by to begin to learn carving letters in stone.

Annual Review 2018

Roel learning to carve letters

 

More flying buttress figurines

After the first set of 26 flying buttress figurines from the north side of the Eusebius Church, we now had to make the 27 from the Southside. But fortunately from flying buttress no. 32 I had already made seven angels in the beginning, plus a girl from buttress no. 36, and Stide had done one as well. Still we've been quite busy with the other 18, and we've not yet finished. Fortunately Jelle has now made a number of them as well. Anyway, on this blog you can read about Blind Man, Woman with Clubfoot, Wise Maiden with Cross, Foolish Maiden with Oil Can and the Supreme Commander In Chief.

Corbels for the Tower

Since in March 2019 the Eusebius Church tower is scheduled to be completed, those sculptures had absolute priority. I've presawn some of the corbels and carved a set of them for the North- and south side of the tower, such as a Woman with Tulips, a Man with Bird, a Man with Ears of Corn, a Woman with two Doves, a Cat with Wings and a Bird beast. Sawing work was mostly done on the corbels from the west side of the tower (12 heads and 5 large corbels), but those were all carved by Stide. Time to once again visit to the scaffolds of the church…

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

follow me on Instagram
and Twitter
and on YouTube

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…

Crockets and finials for Aachen Cathedral

Two new finials for the Aachen Cathedral in Irish bluestone

For Aachen Cathedral some pinnacles had to be replaced. The old ones were worn and had cracked because of rusting iron and because the layering of the stone was not properly applied. The deposition direction of the stone should preferably be processed horizontal, otherwise there is a risk that a long vertical slice breaks off. In this case, they applied it vertically.

The material for these pinnacles is Irish bluestone. It is …Read the whole article…

Llittle praying man (flying buttress figurine for Eusebius Church)

copy of praying man in Muschelkalk limestone copy of praying man in Muschelkalk limestone

Llittle praying man

I'm already quite busy again carving flying buttress 5 from St. Eusebius's Church in Arnhem (the Netherlands). This series consists of a razorbill, a elephant, a sea lion, a Buffalo, a squirrel, a praying little man and for the third time the ark. From the description of the air arc images by the church: …Read the whole article…

A party for ten gable stone reliefs

to the first post about this House Sign↑

Koen van Velzen at the unveiling of the plaque from the Blue Tram street. Ten house signs after designs by cartoonistsBlue, blue, sky-blue

It was a completely blue party, last Thursday in the Blue Tram Street in New Remittance District in Haarlem. I went there, dressed up in my best moody blues, along with my good colleague Serge van Druten, who had also carved two of the ten stones. There was a tiny but excellent band, some blue trim and blue drinks and balloons. It was very unfortunate that Toon van Driel, which started the relief of the Blue Tram street as a cartoon, was unable to come because of an illness. I would have like to talk to him. …Read the whole article…