Saggar for casting

[Suzan]

For my next casting I want to build a ceramic saggar for reinforcement. I've got the Fenton/Kervin book, but I'm still not clear on how it's made.

Do you build the ceramic saggar, bisque fire it, then use the saggar as the mold box for the investment casting? If so, will the investment release from the saggar so it can be reused?

Cheers,
Suzan