TIE- DYEING ACTIVITY

CHEMICAL CONCEPTS Dyes Covalent bonding vs. adsorption Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface. Affinity (hydrophobic/hydrophilic) pH

SAFETY PRECAUTIONS Students should wear old clothes and shoes Reactive dyes are “wash fast” (once the reactive dye makes contact with clothes it will not wash out) Students should wear appropriate protective clothing, goggles, disposable gloves & chemical resistant aprons Dyes on skin & hands will take a couple of days to wash out Do NOT be sloppy in your work… Sodium carbonate activator solution is very basic Be sure to wear gloves when placing the T-shirts in solution & when the shirt is wrung out at the end.

PREPARTION –WHAT TO HAVE READY FOR TOMORROW? Bring in a Ziploc Bag (or small garbage bag) for your final product! Do you have a design in mind? What colors would you like to use? Colors available: RedTeal (Turquoise)Royal Purple YellowGreenOrange BlueSky BlueBlack Hot Pink

CHEMISTRY OF THE ACTIVITY What do we need? 1.T-shirt (100% cotton) -- pre-washed with dish washing soap… Removes the sizing & other material that does not allow for bonding with dyes to occur. Cellulose clearly exposed and ready for further preparation. 2.T-shirts have been soaked in Sodium Carbonate anhydrous solution. Some are dry & some are damp. The ionization of cellulose increases with increasing alkalinity (higher pH – approx. pH8) allows for an adequate number of ionized hydroxyl (-OH) groups in the fiber. Soaking allows for the maximum number of possible bonding sites for the dyes. T-shirts are ready to dye Contact with the reactive dye… bonds are made… longer contact the more successful the bond… Adsorption occurs… what type of bonds are formed?

PROCEDURE : Possible ideas & suggestions: Determine which colors to use … Is more BETTER? Twisting motion to coil the shirt Use rubber bands to reduce the areas of dye contact Pattern building using rubber bands Try your own design

WHEN FINISHED – ON THE WAY HOME Wrap the shirt in some paper towels and place in plastic Ziploc bog OR small trash bag Close the bag to keep the shirt moist. Most colors will have completely reacted after 4 hours but less reactive colors such as green and yellow will take as long as 24 hours. Be patient. Let the dyes react completely