The caulk around the windows on my commercial building were installed about 10 years ago. The caulk, a medium gray color, still looks great. It seals the aluminum framed commercial windows to the block walls.

Reason I ask is I need to cut the bottom of one of my man doors and it frame to install about a 1" tall, solid aluminum sill. Kinda like a dam to keep water out. But I want to use a commercial grade caulk. Not the Home Depot quality caulks offered to us general public. That stuff doesn't even last around a bath tub for a year