Furnace, kiln

Sometimes a mason will endeavor

to make a refractory thing

a kiln or maybe a furnace

for very high temp firing.

Kilns are tricky, they must be

figured to heat up even

and inhaling just right

is a matter of proper breathing.

The area of air intake

and area of exhausting

must be equal and the same

because the fuel is costing

far too much these days

for a kiln to not be heating

in a most efficient way

or the mason takes a beating.