VOA慢速英语 2007 0521a（在线收听）

This is the VOA Special English Development Report.

Dye can bring a little color to life. Most clothing is colored with dyes. Modern, manufactured dyes can be costly. Natural dyes from plant and animal products have been used since ancient times. So this week, we describe a natural way to dye wool.

The advice comes from information written by Jenny Dean of the Intermediate Technology Development Group in Britain. This anti-poverty group is now called Practical Action.

There are several methods to put dye onto material. 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 be clean. Leave it overnight in water and liquid soap. Then wash it with clean water that is a little warm. Gently squeeze out the extra water.

A solution called a mordant is used in the dying process. A mordant helps fix the dye to the material. Traditionally, mordants were found in nature. Wood ash is one example. But chemical mordants such as alum are popular today. Alum is sold in many stores. It is often mixed with cream of tartar, a fine powder commonly used in cooking.

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

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

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

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

Internet users can get the full details at practicalaction, one word, dot o-r-g. Again, the address is practicalaction dot org. And enter the word "dye," d-y-e, in the search box. We will post a link to the site at voaspecialenglish.com.

And that's the VOA Special English Development Report, written by Jill Moss. I'm Steve Ember.