About 15 years ago I had a greenhouse customer that wanted to silicone the joints on hundreds of glass panes on his greenhouse. He had already bought a case of silicone in caulking gun cartridges. The first window took him about half an hour, and what a mess. I then took the gun from him and sealed the next window in under a minute, with a real nice looking bead. The secret to silicone is that you must PUSH the bead ahead of the nozzle! You want to point the nozzle in the direction of travel, and allow a small ball of silicone to ride just in front of the nozzle. I don't use masking tape and I try not to tool it unless I really goofed. Usually a wet finger tip is better than any tool too.
Gary H. Lucas