What makes elements melt and sag?

  1. Getting glaze on the element can cause that to happen.
  2. It can also happen sometimes from a combination of things, not involving direct contact with glaze. For example, the elements in the photograph look pretty worn out. Over their lifetime they are possibly getting different types of glaze fumes and carbon etc. on them. Anything on the surface of the element drives up it's surface temperature. Combine a lot of that with some pottery set too close to an element, reflecting the heat back on to the element right there, and you can get it hot enough locally to melt the element into the element holder.
  3. Glaze fumes can condense on the elements. Good venting can help prevent this.
  4. Be sure to vacuum out element holders to remove any dirt, clay, glaze, etc. that may have settled in there.