NARRATOR:Listen to part of a lecture in an art history class.
MALE PROFESSOR:Ok, now, um, a, a sort of paradigmatic art form of the Middle Ages was stained glass art.Stained glass, of course, is, is simply glass that has been colored and uh cut into pieces and reassembled to form a picture or, or, decorative design.To truly experience the beauty of this decorative glass, you, you should see it with light passing through it, uh, especially sunlight.Which is why stained glass is usually used for windows, but of course it has other uses, especially nowadays.
Um anyway the art of making stained glass windows developed in Europe uh during the Middle Ages and was closely related to church building.In the uh early 1100s, uh, a church-building method was developed that reduced the stress on the walls, so more space could be used for window openings--allowing for large and, and quite elaborate window designs.
Uh back then the artists made their own glass, but first they came up with a design.Uh paper was scarce and expensive, so, so typically they drew the design onto uh a white tabletop.They'd draw the principal outline, but also outline the shape of each piece of glass to be used and uh indicate its color.Now, uh, in the window itself, the pieces of glass would be held together by strips of lead, so, um, so in the drawing, the uh artist would also indicate the location of the lead strips.Uh then you could put uh a big piece of glass on the tabletop and and and see the design right through it, and use it to uh to guide the cutting of the glass into smaller pieces.
MALE STUDENT:And the lead that was just to hold the pieces of glass together?
Well, uh, lead is strong and, and flexible so it is ideal for joining pieces of glass cut in different shapes and sizes.Uh but up to the fifteenth century, the, uh the lead strips also helped create the design--they were worked into the window as, as part of the composition.Um they were used to outline figures, to, to show boundaries--just like you might use solid lines in a pencil drawing.
MALE STUDENT:How did they get the color... I mean how did they color the glass?
MALE PROFESSOR:Well, up until the sixteenth century, uh... stained glass was colored during the glassmaking process itself.Uh you got specific colors by adding metallic compounds to the other glassmaking ingredients.So, uh if you wanted red, you, you added copper, if ou wanted green, you added iron.You just added these compounds to the other ingredients that the glass was made of.
FEMALE STUDENT:So each piece of glass is just one color?
MALE PROFESSOR:Yes, um, at least up until the sixteenth century. uh then they started, um, you started to get painted glass.Uh painted glass windows are still referred to as "stained glass" but the colors were actually painted directly onto clear glass, after the glass was made.So um with this kind of stained glass, you could uh paint a piece of glass with more than one color.
FEMALE STUDENT:And with painted glass, they still used the lead strips?
MALE PROFESSOR:Yes, uh, with really large windows, it took more than one piece of glass, so you still needed lead strips to hold the pieces together.But the painters actually tried to hide them.So it was different from before, when the lead strips were part of the design. And, and it's different because with painted glass the idea of light coming through to create the uh, the magic effect wasn't the focus anymore... the paint work was.
And painted glass windows became very popular- in, in the 19th century people started using them in private houses and, and public buildings.Unfortunately many of the original, stained glass windows were thought to be old-fashioned and...and they were actually destroyed, replaced by painted glass.
FEMALE STUDENT:They actually broke them? That showed good judgment, real foresight, didn’t it?
MALE PROFESSOR:Yes, if only they had known... um and it's not just that old stained glass is really valuable today; we lost possibly great artwork.Uh but luckily there was a revival of the early techniques in the mid-1800s, and, and artists went back to creating colored glass and using the lead strips in their designs.The effects are, are much more beautiful.
In the nineteenth century,uh... Louis Tiffany came up with methods to create beautiful effects uh...without having to paint the glass.He layered pieces of glass and used thin copper strips instead of lead.Which let him make these, these really intricate, flowery designs for stained glass.
Which he used in, in lamp shades--you've heard of Tiffany lamp shades, right?These of course took advantage of the new innovation of electric lighting e-electric lightbulbs don't give quite the same effect as sunlight streaming through stained glass, but it's close.So uh layered glass, Tiffany glass, became very popular and still is today.So um, let's look at some examples of different types of stained glass from each era.
铅条既有硬度也有韧性，所以它是拼接各种形状、大小的玻璃片的理想材料。但是直到 15 世纪，铅条才被考虑成为设计因素和创新所在。铅条才被放到窗户里作为组成的一部分。它们被用作各种素材的轮廓线，就像你们在画铅笔画时外围的实心线。
教授：嗯，直到 16 世纪之前，玻璃画一直都是在玻璃的制造工艺中上色的。假如在炼制玻璃的配方中加入不同的金属混合物，我们就能获得不同颜色的玻璃。譬如，如果想要红色，我们就添加铜；如果要绿色，就添加铁。我们只需要在玻璃成分中加入这些物质就好。
教授：是的，直到 16 世纪都是这样。之后，艺术家们开始，嗯，开始用彩色玻璃。和之前的玻璃一样，彩色玻璃窗名称没有发生变化，依旧被称作镶窗玻璃，但实际上制作工艺却不同了:各种颜色会被喷涂上去， 在玻璃制造出来以后。嗯，这种镶窗玻璃可以使得每一小片玻璃上出现多种颜色。
喷绘彩色玻璃开始变得非常普遍，并且，到了 19 世纪，人们开始用它来装饰私人住宅和其他公共建筑。不幸的是，许多原始的镶窗玻璃被认为过时了，它们都已被损毁，替换成了喷绘彩色玻璃。
教授：哎，是啊，要是当时能够明白就好了，嗯，倒不是说这些老式的镶窗玻璃到今天会有多么有价值，而是我们可能因为它们的损毁失去伟大的艺术品。不过，幸运的是，到了 19 世纪中期，早期的老式工艺有所复兴，艺术家们重新开始在设计中使用有色玻璃和铅条。这些作品就漂亮得多。