The Bad Old Days.

• For most of history, humankind has been cursed with a love of smooth, ironed clothing, a lack of permanent press fabric, and an equal lack of electrical irons. This left us with a limited number of ways to get nice, smooth clothing. Among the most commonly used in the West were flat irons made of cast iron. One of the nicknames for these irons was "sad irons." There were reasons for this nickname.
  
  

What Makes Irons Work.

• A combination of heat and steam softens both animal-based and vegetable-based fibers. Wool, silk, linen and cotton all respond to heat and steam by relaxing and allowing pressure to flatten them out. Of course the same heat and steam can lead to shrinking, felting and bunching if not handled carefully, so most forms of ironing demand close attention or very good automation techniques.
  
  

Hot and Heavy.

• Sad Irons worked by providing the heat element of the formula for flat, smooth clothes, and a lot of the pressure part, too. The heavy irons were placed on the hearth of a burning fire, on the top of a burning woodstove or in proximity to some other strong heat source. They got very hot. So did the room they were in, which may have been wonderful in an arctic winter but was seldom so welcome in many places much of the year. Damp clothing, linens and other fabrics were placed on the ironing board and the sad irons were applied--vigorously. It was human muscle that supplied the pressure that didn't come from weight. Human muscle also kept the iron in motion, smoothing the softened fibers to produce nice, ironed clothes. Most people stuck with the chore did not like it much at all. So while the original meaning of the word "sad" in the term sad iron meant heavy, it came to mean not very happy, also. The irons did the job, but most people were not happy about the process