John Britt's kiln wash is amazing. Not only are my new shelves protected and looking good, but the nasty old shelves with all their old cracked wash are back in working order. This wash covers the old wash so it isn't a problem any more.
Here's the recipe:
Super-Awesome No-Crack Kiln Wash
|Calcined EPK Kaolin||25%|
|G-200 Feldspar||1 – 2%|
|Shelves w/ wash drying in the sun|
And you can read all about it in John's article, The Many Layers of Kiln Wash.