TW: We see the people at the foundry who made the panels, Peter Sylvester, Vinnie Nardone, and Peter Holmstead, as the artists, and we’re the ones who assembled their panels for the facade.

How did you arrive at the decision to use Tombasil?

TW: Our first idea was to try to cast a concrete facade directly on the street, to use the imprint of 53rd Street as the facade. That would have been extremely interesting, but rather disruptive to traffic. We didn’t get a very positive response from the folk art board to the idea of making the facade of cast concrete. So we looked to other materials. We thought of aluminum because aluminum can have some sparkle and shine and it is ordinary enough to be affordable. But once we melted an ingot [of aluminum] and then cast it, it was no longer shiny. It became rather dull and didn’t look like aluminum. So we said, “Let’s look at something that’s not aluminum and not copper, but maybe a mix of the two.” Through a series of investigations, we learned about Tombasil, which is a form of white bronze.

BT: It’s used for boat propellers and fire-hose nozzles, so it can deal with weather. We took the Tombasil to an art foundry because they’re used to dealing with . . .

TW: Odd requests.

BT: We had to work out a lot of technical difficulties because when Pete poured the Tombasil on the concrete floor, the air in the concrete and the moisture caused tiny explosions. We destroyed the floor, but we had some interesting panels. Eventually, we figured out how to pour and cast the material in a controlled way.

That’s a lot of work to get the right material. Is this something that a typical architect can afford to do?

TW: Because this is a public, spectacular building, our process was perhaps more intense than usual. But I think in various ways, all architects can do it. And it doesn’t have to stop here with this project. It’s a baton that one carries and passes to the next architect. Just as titanium panels didn’t start with Frank Gehry and shouldn’t stop with Frank Gehry.

Are there certain materials you would like to work with that you haven’t yet?

TW: Every one on the surface of the earth. They’re all interesting and we try to learn from other architects. We go down to Tucson and see Rick Joy’s house and we’re envious. We go to see Peter Zumthor’s work in Switzerland and we’re envious. And it’s not just the Tombasils and titaniums that are interesting. Something as common as house paint can be exciting when polished to a mirror finish—as we saw recently in a piece of art in the show Open Ends at MoMA.

You’ve said your work must be rooted in time and site. Explain how that relates to materials.

TW: We feel that buildings in general should be connected to the ground, the earth. We think of buildings in terms of heavy and light. There is a notion these days that architecture is increasingly becoming lighter. But I don’t believe it one bit. It’s just an illusion of lightness. Buildings are heavy. I haven’t met a building I could lift.

BT: I think what we’re always looking for is a weightiness—a pressing down—and then a release. We did this at the natatorium at Cranbrook [School of Art], which has a stone floor and is concrete block on the inside. The pool itself is excavated from a hillside. The materials are certainly about durability. But when you look up toward the ceiling, there is that very intense color and the oculus with light coming in, so you get a sort of flight. It’s both roots and wings. We know that materials can be evocative; they can bear emotional weight.

TW: We’re doing something similar with our amphitheater in Guadalajara [june 1999, page 136], which is pushed into the land.

BT: It has the sense of a giant earthwork with battered walls, which are rooted, of course, in the Aztec and Mayan traditions there. We’re trying to think about materials that make sense in the place where we’ll be building. This is the first time we’re working outside the U.S., so the architecture has to have a sense of the climate and be appropriate for the place.

TW: The seating is ground-based, so it’s seen as a kind of land form. And there’s a very big roof that is both light and heavy. On the underside of the roof, we’re using an expanded-metal mesh that we’ve seen in Mexico as a fencing material.

BT: The stuff is really cheap, very crude, and made in Mexico.

TW: The material itself weighs seven pounds per square foot or so. If you look at it straight on, it’s maybe 85 percent transparent. But from an angle it looks almost solid. So is it light or is it heavy?

BT: An important value for us is drawing together all of the various elements of architecture—materials, space, form, light, color—and producing a unified whole. We’re not at all interested in producing a collage. People’s lives are the collage and you don’t need a collage on top of a collage. You need to provide some sense of wholeness so the kaleidoscope can occur within it.

TW: The issue of the hybrid is interesting. It’s not wrong to recognize that odd partners can come together. We’re a perfect example of that ourselves. But I think it’s very, very important that one show restraint in order to let certain things come to the fore and have some force and authority.