Spraying without a mask = death (either very quickly, or very painfully)
I even use a mask now with spray bombs just because aerosol gets everywhere.
I know too many people with lung problems from not wearing a mask.
also, I have used Rustoleum over POR15 as a top-coat. Worked great. Dont know how long it lasted, as I sold the truck to get a bigger down payment for the house.
Scott