Dye can bring a little color to life. Most clothing is colored with dyes. Modern

Dye (染料) can bring a little color to life. Most clothing is colored withdyes. Modern, manufactured dyes can be costly. Natural dyes from plant andanimal products have been used since ancient times. So this week, we describe anatural way to dye wool.

There are several methods to put dye ontomaterial. The vat method, for example, can be used to dye wool with onionskins.For this example, use one hundred grams of natural wool. The wool must beclean. Leave it overnight in water and liquid soap. Then wash it with cleanwater that is a little warm. Gently squeeze out the extra water.

A solution called a mordant (媒染) is used in the dyingprocess. A mordant helps fix the dye to the material. Traditionally, mordantswere found in nature. Wool ash is one example. But chemical mordants such asalum are popular today. Alum is sold in many stores. It is often mixed withcream of tartar, a fine powder commonly used in cooking.

Mix eight grams of alum with seven grams ofcream of tartar in a small amount of hot water. Add the solution to a metal panof cool water. Next, add the wool and place the mixture over heat. Slowly bringthe liquid to eighty-two degrees Celsius. Heat the mixture for forty-fiveminutes. After it cools, remove the wool and wash it.

To prepare the dye solution, cover thirty gramsof onionskins with water. Use only the dry, brown outer skins. Boil the liquiduntil the onionskins lose their color, about forty-five minutes. Remove theskins after the dye cools.

Now it is time to dye the wool. Place thewool into the dye and heat the mixture. Bring it to a boil, then immediatelyreduce the heat to eighty-two degrees. Now heat the dye for about forty-fiveminutes or until the wool is the desired color. Keep in mind that wet woollooks darker than it is.

Once the dye cools, remove the wool andwash it. Now the wool is orange or yellow. Or at least it should be.

57. According to the passage, mordants are________.

A. dyes used in the dying process

B. materials which will be put dye to

C. wood ashes used in the dying process

D. not dyes but play an important role inthe dying process

58. Which of the following statements about“natural dyes” is true?

A. They might be cheaper than chemicaldyes.

B. They are more expensive than chemicaldyes.

C. They have been used for only recentyears.

D. They are all made from animal products.

59. As for the vat method, which of thefollowing statements is NOT necessarily needed?

A.Ash.               B. Water.           C.Mordant.             D. Temperature.

60. Choose the proper order of dying wool:

a. boil the liquid with onionskins.

b. add mordants to a metal pan of coolwater.

c. wash the wool with clean water.

d. put the wool into the liquid and heat it

e. heat the mixture and then wash it.

A. c, b, e, a,d        B. e, b, c, d,a     C. b, e, a, d,c             D. a, b, e, c, d

试题答案

【答案】

57---60   DAAA

【解析】略