What are graded elements and how do they work? Does L&L use them?

What are graded elements and how do they work? Does L&L use them?
  1. Graded elements are one way kiln manufacturers adjust for the natural top to bottom temperature variations in a kiln. 
  2. Graded elements are great when a kiln is brand new. However, elements age and with different elements in the same kiln they will age at different rates. If you have to change one element (ruined by glaze, for instance) and not the whole set of elements, your kiln may not be so even. This process is also accelerated by higher temperatures.
  3. Zone control dynamically deals with any such changes and maintains its evenness over time and under different loading conditions.
  4. L&L uses graded elements on its new School-Master kilns because the temperatures are not so extreme and it allows us to use the less expensive single zone controllers.