I used to have the most wicked job title. I was a 10 Micron Particle Aerosol Science Research and Development Technician. Fancy title for an assembler. We built large Aluminum venturi systems mandated by the government to test pollution in Colorado factories for 10 micron particles. The cost $10,000 each. Where the heck is this story going? We used 100% Silicone to seal the aluminum venturi systems. That was my job.
Silicone worked good enough on aluminum for a $10,000 dollar machine.