Determine the Type of Fabric
When purchasing new fabric, read the end cap of the cardboard sleeve the bolt of fabric is wrapped around or the attached tag. Make a note of the type of fabric and any care instructions listed.
Testing Your Iron
Iron temperature settings differ by manufacturer, but most have the heat settings for each type of fabric printed on the temperature dial. Nevertheless, it's important to test a hot iron on a scrap of fabric first before ironing any large pieces for your project. Your iron may run a little hotter or cooler than what is needed. Adjust your iron temperature accordingly. You want a temperature hot enough to smooth the wrinkles, but not so hot that it damages the fabric. If temperature is critical, use a thermocouple and a multimeter to test your iron.
Heat Settings for Fabrics
Use these basic iron temperature setting guidelines for your fabrics: acetate, 290 F; acrylic or nylon, 275 F; cotton, 400 F; linen, 445 F; polyester, silk or wool, 300 F; rayon, 375 F; triacetate, 390 F. For blended fabrics, use the lowest temperature recommended for the fibers in the blend.