If you put units into your porcelain furnace, and you are using CAP Zirconia and they come out too dark they can be saved!
This program can lighten your units:
500c Start temp.
0 Dry time
60c Heat rate
850c High temp
1:30 Hold time
2:00 Minute Cool
This has been working great for us and want to pass this along. Again, you must be using CAP Zirconia.