The conservator’s eye: Taddeo Gaddi, Saint Julian

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Dr. Steven Zucker: [0:10] We’re up on the second floor of the Metropolitan Museum of Art, looking at a small panel painting by an Italian artist whose name is Gaddi, one of the most prolific students of Giotto.

Corey D’Augustine: [0:16] This is an egg tempera painting.

Dr. Zucker: [0:17] We generally think of Old Master paintings as being oil paint on canvas.

Corey: [0:21] In southern Europe we have a tradition dating back all the way to the Middle Ages of painting in egg, whereas oil painting is really a northern tradition.

Dr. Zucker: [0:29] Why egg yolk?

Corey: [0:30] These artists are very concerned with binding pigment — all of these colored powders, etc., many of them mineral — binding those colors to the wood panel, the support that these works are often painted on, in a way that’s going to be durable.

Dr. Zucker: [0:41] They were durable. These are over 500 years old.

Corey: [0:44] These paintings are coming out of a very highly refined tradition of painting guilds. The way this would work is that as an apprentice, you would train for often seven years under a master. Understanding not only how to paint beautifully, but how to make sure that your painting lasts for as long as possible with no visible change.

Dr. Zucker: [1:00] That makes sense given the subject. We’re at an image of Saint Julian.

Corey: [1:07] It’s painted on poplar wood, a rather soft wood. It’s one that warps a lot over time.

Dr. Zucker: [1:09] We can see that the surface does bulge towards the center.

Corey: [1:12] In fact, it probably would have done so even more before it was restored in the 19th century. A lot of these paintings have been planed down from the reverse and mounted onto a cradle, a rigid wooden structure in the back that doesn’t allow it to flex naturally.

[1:26] We tend to think that deforestation is a very contemporary problem, but the hardwoods of Italy were already deforested by the early and middle Renaissance. This is why they’re painting on poplar. They knew it wasn’t the best wood. They knew it would change, but they didn’t have a choice.

Dr. Zucker: [1:39] That’s not the only change. It’s pretty clear that the lovely Gothic arch that the saint is surrounded by would have ended with its point. Here, it’s been cut off.

Corey: [1:49] Almost all of the Renaissance paintings that you’ll find in museums around the world are only small fragments of what would’ve been very large altarpieces.

Dr. Zucker: [1:56] It would have been part of a multi-paneled polyptych. We need to, of course, think back to a period before air conditioning.

Corey: [2:02] Where are you supposed to encounter this painting? Certainly not here at the Metropolitan, but in a church in northern Italy. A non-heated, non-cooled environment, super humid and then super dry depending on times of the year. This is a very harsh environment for any work of art.

Dr. Zucker: [2:15] The wood itself is expanding and contracting. Presumably, there’s the potential that the paint itself could loosen.

Corey: [2:21] Wood has this ability to expand and contract again. No problem. Paint does not have that ability, however. That’s the reason why paint very often cracks so extensively on these panel paintings.

Dr. Zucker: [2:31] Wood is absorbent and so you wouldn’t want to paint directly on the wood.

Corey: [2:34] What these artists and artisans would do is use rabbit skin glue, glue made from the skin of rabbits, that’s a size material. In other words, it’s a sealant of that wood, and it limits the ability of that wood to absorb moisture.

Dr. Zucker: [2:46] On top of the rabbit skin glue, an additional layer of seal is added. This is known as gesso.

Corey: [2:51] The gesso, or the ground, or the priming of the painting, is actually a mixture of rabbit skin glue again and then some gypsum, calcium sulfate, some white powder, in other words. This is an absorbent material, which is now going to receive the egg tempera paint and also, in areas under the gold, a material called bole, a kind of clay.

[3:09] It’s often reddish in color — it is in this painting — and that clay is again mixed with rabbit skin glue. There’s a whole lot of glue all throughout the layer structure of this painting, it’s part of the reason why it’s so durable.

Dr. Zucker: [3:19] Let’s talk about the paint for just a moment. Tempera is painted with a very small brush.

Corey: [0:00] That’s right.

Dr. Zucker: [3:24] With very fine brush strokes.

Corey: [3:26] Egg tempera dries quite rapidly and is very difficult to work wet-in-wet like you can with oil, brushing wet paint into wet paint that’s already on your panel. Here, this is much more like a drawing technique because you have all these individual crisp little lines.

[3:41] The face here is incredibly well-preserved and we see all of these beautiful, they almost look like pencil lines, and really that’s the tip of the brush. We can imagine how painstaking this process is to be able to make this degree of modeling and illusionism essentially with pencil lines.

Dr. Zucker: [3:54] While the face is really well-preserved, the red garment seems to be flat.

Corey: [3:59] Remember that these were in churches for hundreds of years and they were cleaned by not conservators but monks and nuns. The candle soot and the grime that would collect on these paintings had to be removed with very strong materials, urine and lye, believe it or not.

[4:13] These are very corrosive substances. A lot of the upper brushwork, the higher layers of the paint, sadly have been scrubbed off, and this probably happened hundreds of years ago.

Dr. Zucker: [4:20] It’s a little misleading to call this a painting because only about 50 percent of the surface is actually paint, the rest of it is gold.

Corey: [4:27] Gold is one of the only noble metals that we have. It’s a metal that doesn’t tarnish. The message here is — yes, it is expensive, it’s luxurious, it’s appropriate for a religious painting — but deeply embedded in that meaning is also the fact that this is timeless, it doesn’t corrode.

Dr. Zucker: [4:40] The gold leaf, which is actual gold that has been hammered very, very thin, then applied and burnished. A smooth object is rubbed over it. What we’re seeing here is just a faint trace of the original gleam that the gold would have had.

Corey: [4:53] This is water-gilding technique. The bole is moistened slightly and that’s all the adhesion necessary for this incredibly thin sheet of gold. Now, after the gold is applied, there are small metal tools which make all of these beautiful little indentations.

[5:05] Again, we’re not supposed to be at the Met, we’re supposed to be on our knees in candlelight and that light is flickering and refracting off of all those little nooks and crannies. It’s part of the magic of these paintings.

Dr. Zucker: [5:15] It is too easy to forget about the incense, the music, the lighting.

Corey: [5:18] The entire point of water gilding is to make it look solid, and even though we know there’s just a tiny thickness of gold leaf there, these craftsmen were so good that they provided the illusion of solid gold.

Dr. Zucker: [5:29] This is really an art of illusion, trying to produce an object, costly because of its labor, that looked like it was costly because of its material.

Corey: [5:38] In the early Renaissance, we have this great paradox that, on the one hand, where does this scene take place? In a world of gold, perhaps that’s heaven. At the same time, this figure is painted quite illusionistically. I can imagine talking to that saint.

Dr. Zucker: [5:50] This artist was the student of Giotto, who is credited with dramatically furthering the idea that he could represent figures that looked as if they were in a world that we recognize, that they had mass and volume, that they cast shadow.

Corey: [6:04] We have one foot in the Middle Ages, this world of gold. We have another foot defiantly here on Earth. In other words, we have heaven on earth. This is a powerful motif for these devotional paintings.

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