 My name is Dan Allen, and I teach part of a course here at Columbia called Brickstone and Terracotta, and today I'm going to be talking about architectural terracotta. This is a mixture of clays, unfired, and some ground up previously fired clay, mixed together, usually pressed into a mold to form its shape, then dried and fired. So it's fired earth, basically. It's very similar to the ceramic masonry that we use as bricks. But it has a great deal more variety, a great deal more possibilities in how it can appear, what it can do for us in terms of the built environment. I've assembled just a couple of samples that are here at our laboratory. Each one of them has a history of its own, but they represent really two of the three kinds of terracotta that we typically encounter here in the built environment in New York. The first of these is a simple balustra base, and this is what is referred to as slip coated terracotta. So if you take a look at it closely, you'll see that it's very matte. It's not shiny. It's got these little speckles. This represents a kind of terracotta that we see a great deal here in New York. It's an effort to make this substitute material look like limestone. And the way it's done is to apply a liquefied clay, not a vitreous glaze in this case, not a glassy or shiny glaze, but a liquefied clay to the surface before firing and then fire it. These little flecks tend to add to the impression that it's limestone. If you take a look here, you'll see that indeed the slip coating is really only a few micrometers thick. It's really skin deep, and that's the case with all terracotta. Almost all terracotta has a body that is similar to this, not very exciting in itself, but is dressed up either with a slip or a glaze. This next piece is a beautiful piece that is from a Blum Brothers building, one of which I think we'll go look at on our brief walking tour. Here's a fantastic bit of deep ornament done, and it's done with a vitreous glaze. In this case, a rather matte vitreous glaze. It's, I'm afraid, a bit dirty since it's from around 1900, a little after. And we can see a couple of important things about the way terracotta is made by looking at this. First, again, the glaze is only skin deep. Here the glaze is fired to the surface, and here we see a condition that is related to glaze fit, often referred to as craquelure or crazing. Here, the body, the ceramic body, as all ceramic bodies do, is expanding slightly over time with the absorption of atmospheric moisture. It's an irreversible expansion, so it's getting a little bigger. But the glaze, which is very, very stiff and vitreous, cannot do that. So it crazes along these lines and forms this wonderful spider web. It's how you're going, you know, you're looking at a piece of glazed, sometimes slip coated terracotta. But here's some other interesting things about this piece. Here's a setting mark, which tells the mason where it goes on the building. So it's a letter number code, because a lot of these things look alike. And there's a reason for that. They're all made in a plaster mold. And that leads us to the back of these units, which shows you really how they're made. So here, a shoebox type mold made of pottery plaster would have been used, and the wet clay, the uncured clay, is pressed in by hand. And in fact, we can see some of the fingerprints of the people that pressed this way back probably about 120 years ago. This is a web that's built up for stiffness. But if you take a look at the material, you'll realize almost none of it is more than about two inches thick, about an inch and three quarters to two inches thick. And the reason for that is to allow the clay to dry out sufficiently so that it can then be fired. So the terracotta has to be made. The unit has to be made one inch larger per foot in its wet form, in the plastic clay form, so that it will shrink a certain point in drying. And then once all the water is gone, it will shrink further in firing and it should come down to the correct size. That's one of the things that makes replacing terracotta interesting and complicated because we cannot do a one-to-one mold replacement. We have to make a mold, make a larger positive, larger mold, and then push it down. We've pressed a lot of terracotta here in the lab over the years with students, and we've had the good fortune of firing many of these pieces at Teachers College in their ceramics lab. Here's an example of a higher style glaze, a shinier glaze. But again, you can see it's only a little bit, it's only a very thin skin. And underneath it, we can see the ceramic body, which is a mixture of ball clays and previously fired clay. If you look very closely, you'll see little white flecks, which are probably what's referred to as temper or grog. Temper or grog is pre-fired clay, usually pre-fired ceramic material that's mixed into the mix up to about 30%. And what that does is it controls shrinkage and it controls warping during firing. So it's basically a material that's already been through the firing process. When we fire any ceramic, what we're trying to achieve is something called sintering. At a certain set temperature, everything starts to fuse and it begins a careful partial transition towards glass or glassy state. And to that end, when we hit a well-fired ceramic against itself, we get a slight ringing sound. And indeed, that's how we test terracotta in a simple way in the field by hitting it with a hammer to understand whether it is indeed well bonded or if there are in fact discontinuous elements. These are lovely glaze samples from the old St. George Hotel in Brooklyn Heights at 111 Hick Street. These were done for a project of some very beautiful decorative urns and pillars that are on the roof of the complex that served as decoration for what must have been one of the most beautiful rooftop bars in American history. It's a 1929 hotel skyscraper in Brooklyn Heights. Those are our samples and maybe our next stop is to go take a look at some of these pieces in service. So now we're outdoors on the campus of Barnard College and we're here to look at a remarkable terracotta brick and limestone building called Millbank Hall. It's one of the instructional buildings here at Barnard. The terracotta here comes from the south shore of Staten Island from the Crusherville people who also made some of the very, very characteristic rough and brown colored brick that makes up the Matthews model housing that we see so often in the outer boroughs. But here we're seeing terracotta used both as a reproducible material and as a substitute for limestone, but also in this case as a very special decorative touch to the building here. If we look at these medallions, the lion and the shield, we can see not just the simple molding and demolding of terracotta, but a great deal of handwork. So probably the pieces were pressed into a mold to begin with, but then taken out and while the clay is still plastic, still workable, a great deal of work with hands and hand tools was done to increase the level of visual interest of the medallions. Take a close look at it and you'll see it's very, very dissimilar from carved stone. The curves around her, the way it's produced clearly shows how it was produced indicates how it was produced in a plastic material, material that can be molded with the hand and would perhaps a soft wooden tool rather than sliced into with a hard chisel. It's what separates terracotta from carved stone, but it's also what gives us a great possibility of detail and it really shows up here at Barnard. So now we're on Claremont Avenue just west of the Barnard campus where we were a moment ago and we're looking at a couple of buildings from around 1910 by an architect apartment house designer named Gaetano Aiello. And I hope we have a chance to take a really good look at it. If you're ever in the neighborhood, please come by and take a look. They are remarkable and they're remarkable in their use of terracotta as much as an advertising tool as anything else. If we think about what's going on in New York City at the turn of the 20th century, the city is expanding rapidly and we're trying to convince New Yorkers that it's okay to live in apartment buildings. We're calling them French flats. We're pushing the idea that living in an apartment building doesn't have the bad connotation that living in the tenement does. And so part of the way of doing that is to advertise these buildings as being truly, truly grand and terracotta falls in as the perfect material to do that. It's reproducible. So if you take a look, we have everything in these buildings. We have false balconies. We have winged angels with shields. We have rope moldings at all the corners. Just a riot of detail. A detail only made possible by the repetitious molded work of terracotta. And here it's being used as pretty much flat out advertising. There's nothing remarkable about the layouts of these apartments. It's really just an effort to get New Yorkers to live with the idea of living in an apartment building, to make it grand and seductive. And this is a perfect example of that. All of this material is slip and lightly glazed terracotta and below the third floor sill level is all a marble. And the marble obviously is aging not as well as the terracotta, which is in itself paradoxical. The substitute material here typically aging better than the natural stone. So now we're on Riverside Drive and we're looking at a remarkable pair of buildings, the Cambridge and the Oxford, which are from a year after the buildings designed by Gattella Ayano that we looked at just now. These are by a remarkable pair of architects, the Blum Brothers, George and Edward Blum, who studied the Occult of Beaux-Arts but really paid attention to what was going on in Paris. And so these buildings, unlike Ayello's buildings, are far less derivative. There are no winged angels. There are no classical motifs here. The ornament is handled beautifully in terracotta really as a very modern repeat pattern. If you take a look at the small squares with the foliated ornament, you'll see that they mix and match and they create a wonderful surface that is really far more considered in modern than the work that Ayello was doing with his winged angels. With his winged angels and rope moldings. So here the Blum Brothers are really using terracotta as terracotta, not really trying to imitate stone at all, although the ground floor is still a stone facade. So truly interesting work by the Blum Brothers here in a building that's actually owned by Columbia University. So now this is our last stop. We're standing across the street from the corner of 115th Street and Broadway at a building that has a unique place in New York City building history. This apartment building, owned by Columbia University, was the site of a terrible tragedy in the spring of 1979. A young woman named Grace Gold was walking. She was a student at Barnard and she was killed by a piece of fallen terracotta. It's something that's given terracotta a very bad name. You can see what happened after that, a number of things. First, the owners of the building came along and they stripped off all the ornament. If you take a look, this building was really the sister building of the one a little bit further north. And so you can see that we don't take that kind of scorched earth approach anymore. The other thing that happened that's really important to our story is the passage of a local ordinance, local law 10 of 1980. Local law 10 of 1980 was the first time that New York City mandated that licensed architects and engineers had to inspect all buildings over six stories in height every five years and file a report as to the safety of their facades. That law is now called FISH, the facade inspection and safety program, but it really gave birth to an entire restoration industry. And if you think about it, New York City in 1979 and 1980 was pretty much on its last legs. It would come very close to being bankrupt and the buildings were not being well taken care of. Now it's hard to imagine, as wealthy as cities we are, that buildings would simply fall into disrepair, but the times were very different then. So much has been done since then to make New York City a safer place. And so much of that has actually led to improved methods, techniques and materials for restoring buildings. When the tragedy happened here in 1979, it really wasn't a functioning terracotta industry in America. The idea of replacing a piece of terracotta with a new fired ceramic piece of terracotta was pretty much unheard of. And now, while it's not commonplace, it is frequently done. And there's a lot of good restoration work being done. And we owe a lot to the terrible thing that happened here in 1979. Well, we just sort of figured it out here in the lab by doing some basic math. I've been involved in terracotta on and off for 38 years, getting my start with the material as a mold maker back when I was studying art here in New York City at Cooper Union. After that, it is figured very heavily in my career, wrote my thesis on it here at Columbia in the preservation program. And I've been restoring terracotta buildings specifying terracotta and dealing with it as an architect for something like 25 30 years now. So terracotta is really of its time that the majority of terracotta here in New York is the result of a really rapid urbanization of America after the Civil War and going into the 20th century, pretty much dying out as a huge concern around the time of the Civil War two. It tells us a lot about what was important to New Yorkers. I'm using New Yorkers but really Americans, in terms of constructing new cities. It was a way to make new fireproof buildings that fit into the urban landscape, and a way to democratize ornament to the point where almost anything could be made intricate and beautiful, really just to the imagination of the builders. So it's a remarkable material in that it's both handmade, but also mass produced. And so in some ways it's a perfect material for the early 20th century American Well, we have a lot of terracotta facades here in New York, let's face it, a great percentage of our of our early 20th century buildings contain at least some terracotta many of them are all terracotta facades so we encounter it really every day in preservation practice here in New York. I suspect it's the same in other cities I certainly know it isn't Chicago and San Francisco and certainly in Boston terracotta has its own unique issues. It's related to how it's made, how it's fired, its nature as a ceramic material, but also how it's configured and how it's put together, and it's put together in ways that the builders chose to put it together, which can sometimes be very problematic. Well, sure. There are a lot of resources where you can learn about terracotta. Certainly there's a lot of the library for those of us who have access to that. There's an organization called friends of terracotta, largely run by Susan tunic used to teach this course. They have a website, and they publish a newsletter. You can also check out the websites of the two American manufacturers that are still in business. I'm glad I'm McBean and Boston Valley terracotta both of whom have a great connection to this program in terms of hiring our graduates and also supplying sample materials to us. That's a good start but also just walking around walking around your city and looking up because a lot of terracotta was used as a substitute material above the third floor level in for example, early 20th century apartment buildings. Once you recognize the material, you'll find that it's really everywhere. It's everywhere in commercial strips in the outer boroughs. It's there in apartment buildings here in New York. It's there throughout the garment district in the in the high rise urban factories that are such an important component of our town. It's everywhere. And once you start getting sensitized to it, simply looking at it and looking at how it's put together and really the genius of its ability to democratize ornament is I think a great place for anybody to start whether you're a technician or someone who just appreciates beautiful buildings.