Divide your students into groups in a sectioned-off science lab. Give each group a different common household fabric. Each group should receive three equally sized swatches of one of these fabrics: nylon, satin, taffeta, terry cloth, cotton, linen and rayon. At each station place a bucket of water where the students will drop the burning pieces to extinguish them. All students should be wearing safety goggles. Have the students fold their fabric in half to ensure the flames engulf the entire material. Hold the flame from a long grill match or grill lighter directly to the cloth. Let each burn for 15 seconds. Repeat for the other two patches. Have the students compare their burnt fabrics to see which ones sustained the most damage. Those are the most flammable.
Divide students into three groups. Give each group a baby's onesie, which is a T-shirt for infants that snaps at the bottom, in a different color. One group should get white, another should get blue and the next group should get pink. Make sure the brand of the onesie is the same to ensure consistency. Cut six four-inch squares of material from the onesies. Make sure the students are wearing safety goggles and flame resistant aprons as they light the squares on fire one at a time with a long grill match or grill lighter. Time how long it takes for the cloth to burn completely. Repeat for all the other squares to get an average result. Have the groups compare their results. The numbers should prove whether dye affects flammability.
To get pure fabric lint, thoroughly clean your lint traps before beginning this experiment. Wash and dry one load of 100 percent cotton clothing. Collect the lint. Again, clean the lint trap thoroughly. Then wash and dry one load of 100 percent polyester clothing. Collect the lint. Roll the lint into compact balls and cover them with petroleum jelly to slow the burning process. Once goggles and flame-resistant aprons are in place, set the cotton lint ball on fire and time it to see how long it takes to burn completely. Repeat for the polyester.
Hand out 6-by-2-inch swatches of unwashed cotton, polyester, cotton-polyester, fleece and nylon to the students. Suspend the fabric above the work tables by hanging them from a taut string with a clothes pin. After they don their protective gear, have the students light the fabrics from the bottom and let them burn for five seconds before extinguishing the flames by dipping the cloths in water. Measure the amount of cloth burned. Repeat this sequence for swatches of the same fabrics that have been washed in fabric softener. The results will show whether fabric softener increases flammability.