COAST TO COAST AM WITH GEORGE NOORY

Reader's Comment:
If you would like to know what the synthetic material labeled Kirby's Find is, I can tell you. It has been about 25 years since I have worked with this material, but I recognized it as soon as I saw it. It is a piece of extruded rigid vinyl plastic. The extruder is a huge metal screw inside of a metal cylindrical chamber. The raw materials for the plastic are mixed and heated in a machine called a banbury.

From the banbury, the material is dumped into the extruder chamber where it is pushed toward the front of the extruder by the rotating screw. When the plastic reaches the front of the extruder it is forced through a set of screens that are mounted on the back of a 2 inch thick metal plate. The metal plate has equally spaced holes that go all the way through. The plastic is forced through these holes after it passes through the screens. The screens serve to remove impurities that are in the plastic. After the plastic is pushed through the metal plate holes it fills the front of the cylindrical chamber, which is shaped like a funnel with an opening in the shape of a 3 inch slot.

The plastic escapes through this slot, where it is cut off by an automatic guillotine knife when the right amount has escaped. The small pieces that are cut off are conveyed to a series of hot and then cold steel rolls. These sets of rolls are part of a machine called a calendar. The purpose of the calendar is to roll the hot plastic into sheets of plastic. The thickness varies, depending on what it is going to be used for.

The piece shown on your web site is what is left inside of the extruder at the end of a production run. This is always taken out and discarded. This plastic was probably white, but is off color because it sat in the extruder head too long before it was removed. When this happens, the plastic gets too hot and takes on a burnt appearance. Much of the plastic sheeting that was produced 35 years ago and after was used to make credit cards. So what you have here is a lot of credit cards that never made it to final production.

--Ken J.