WarmGlass.com

Ok here goes. I have a coffin kiln with inside wall to wall distance of 25".
My piece is 24" and my kiln shelf is 21 or 22". I was thinking of firing on
Sand or plaster. The distance of the floor from the first coil is an inch
Or so. Is that enough thickness of material i end up using to work. I have
Never attempted this before so i so i'm quite apprehensive about
ruining my kiln or my glass.

You only have 1/2 inch to the kiln wall and the elements, can you make the glass design smaller? You risk a lot from glass on the elements and uneven heating and annealing, even if the sand doesn't get in the element grooves.