Transcript Tie-Dye
Tie-Dye T-Shirts History Tie dye shirts became popular in the 1960’s when they were an extreme fashion statement. History Tie-dye dates back to ancient times. Tie-dye became fully developed in China during the T'ang dynasty (618-906 A.D.) and in Japan during the Nara period (552-794 A.D.). THE CHEMISTRY IN TIE-DIE The DIE Each different die is made of different dye molecules Each different shape of die molecule absorbs light differently THE T-SHIRT The fabric your clothing is made out of is also made of molecules Cotton is made of long strands of cellulose molecules, all twisted together Cellulose is also in wood THE COMBINATION If you put these two molecules together nothing will happen. You need an atom on the surface to get the two molecules to stick together You use baking soda (sodium carbonate) on the fabric which will make the dye stick to the cloth. Then it will be permanent. Bonding in Tie-Dying Covalent Bonding in Tie-Dying Fiber reactive dyes attach permanently to cellulose fibers using a covalent (electronsharing) bond. These molecules carry a "chromophore" which absorb varying spectra of the light, allowing only certain spectra to reflect. Covalent bonding is one of the most basic and strongest types of chemical reactions. This reaction happens gradually over time depending on temperature and/or the Ph level of the surrounding environment. The Ph level is affected by soda ash and baking soda. Time needed for bonding The dye is allowed to react in a desirable host environment for up to 24 hours. After this time, the bonding sites on the cellulose should be saturated with dye molecules. Excess dye molecules that have not bonded permanently are washed away using warm water rinse and a dye-carrying detergent like Synthrapol. Diagram of Covalent Bonding Soda Ash What is soda ash? Soda carbonate Na2CO3 Not as acidic as sodium bicarbonate (baking soda) NaHCO3 Baking soda decomposes at a high temp to form the ash. Purpose and Use Purpose increase the pH Changes the pH of the fiber reactive dye so it’s a permanent connection for the dye and fiber It activates the molecules in the fiber so it can chemically attack the dye Chemistry in the Dyes Dyestuffs The process of dyeing-the immersion of a fabric solution of a dyestuff in water. Dyestuffs were central to the Industrial Revolution How it colors the shirt Dye chemist, Otto N. Witt proposed a new theory of color and constitution that explains that atoms called chromophores The chromophores give rise to the colors Auxochromes Auxochromes enable the bonding to fiber and modify the color However some dyes such as mordant dyes can only bond using a fixing agent Tie-dyeing is a selective dyeing where you choose whether the dye bonds. Should you wash new clothes? everyone should be aware that new clothes, towels or even sheets might contain toxic chemicals like formaldehyde. Formaldehyde? Yep, that's right, the chemical used in biology labs for preserving dead animals and body parts. There are several reasons that manufacturers use formaldehyde. It is believed that some of the chemicals help keep the fabric stain free, wrinkle free and disinfected. But more importantly, it should be made clear that formaldehyde is considered a carcinogen, a cancer causing agent. One common reason to apply chemicals is mildew. Clothes that are made of natural fibers, such as cotton and linen, can mildew if they are exposed to moisture. Manufacturers use formaldehyde to treat clothes that have to be shipped a long way, say, from Asia to the United States, to prevent mildew. Why We Use Urea What is Urea? Urea is the same chemical as is found in the urine of mammals the urea we buy is not obtained from urine It is synthesized from natural gas Any dye supplier should be able to sell you clean urea Why is it used? Urea has two purposes: it can make it possible to dissolve more dye in a given volume, for the strongest of colors it serves as a humectant, or water-attractor, to help keep fabric damp long enough for the reaction to occur. You can do without urea if your dye solutions are strong enough for your needs without it, and you keep your fabric damp in some other way, such as by covering with plastic.