Why do kilns rust
Rust formation on kilns is normal and unfortunately unavoidable.
Corrosive Fumes:
Sulphur and other chemicals burn out of the clay during firing and create corrosive gases that contribute to rust.
Firing Damp Greenware:
Firing clay that is not fully dried releases excessive moisture which contributes to rust.
Kilns, especially those in humid areas, are prone to moisture buildup which accelerates rust. If situated near the ocean salt in the air further impedes water evaporation, leading to more moisture buildup.
Yes! There are there ways to mitigate rust on your kiln...
Bisque bone dry pots:
Ensure greenware is bone dry before firing to minimise the amount of steam released into the kilns internal and external atmosphere.
Ventilation during Firing:
Ensure proper manual or mechanical* ventilation of the kiln during firing and always allow fresh air to fully circulate in the kiln room during firing to allow corrosive gases and moisture to escape. You can encourage fresh air circulation by having windows and doors open and running an oscillating floor or desk fan near the kiln.
*Orton Vent Masters are specifically designed to remove moisture and gases from the atmosphere inside the kiln and they also provide other benefits - check out Orton Vent Masters here.