What is the right temperature to fire to on the first firing?

A customer asks: I have a question regarding this first test firing. For my previous kiln, I remember I fired the first firing up to one cone higher than I was working... in that case it was cone 6 - so I fired it it to cone 7.... I am going through the instruction book and videos (which are great and extremely helpful) and the recommendation for the first firing is to cone 5. I plan to work up to cone 6 again with this kiln - possibly higher. My question is: Should I do the first firing as instructed to cone 5 and then a second firing to cone 7 after? Can I fire the first firing to cone 7? I want to season the kiln properly - I certainly don't want to jeopardize it for the future.

Answer: The Cone 5 temperature target is somewhat arbitrary. We want to accomplish three things with the first firing: 1) fuse the hardening coating we apply to the surface of the tops and bottoms and 2) seat the elements in the holders and 3) put an initial oxide coating on the elements (which protects them from contaminants in the atmosphere from clay and glazes).