Skylighter's latest blog post included the specs for various types of fuses. I recently used some green Visco to time the retro motor on the Backdraft and thought I capture that info for future reference.
These fuses are all BP-based. I haven't even seen any Thermalite for about 10 years so if anybody has a photo or burn rate specs I'd appreciate them. Just for completeness.
Fuse Burn Rates
American Visco - 2.5 seconds per inch
Chinese Visco - 1.7 seconds per inch
Fast Visco - 0.25 seconds per inch
Fast Fuse - 0.1 - 0.15 seconds per inch
Time Fuse - 2.2 - 3 seconds per inch
Quickmatch - Instantaneous
Foil-Taped Fast Visco - Instantaneous
Foil-Taped Fast Fuse - Instantaneous
Thermalite (Fast) - TBD
Thermalite (slow) - TBD
Update: Jess from Skylighter cautions:
These should be seen as appoximations. They were the times that Ned got from the particular fuses he tested. You should always test burn a piece of fuse from every new roll you get as the times can vary slightly from one batch to another, escpecially on the viscos and time fuse.