When I blast I would freeze everything first. And I used the whippet branded butane from the corner store that was next door to where I lived. Yields can vary a lot brand to brand, and sometimes can to can in a single brand. Even on highly refined 9x+ cans. I just get what's affordable and refined at least 9x.
I blast outside, with at least one barefoot on concrete, and I left the dish outside until it was done bubbling. Even in the dead of an icy Kansas city winter, I grounded my body outside directly to earth. No chances taken.
I had an acquaintance in KC that worked at the same facility nearly die, and set his house on fire because he blasted inside, during dry winter months, with plenty of ventilation, because his shirt made a static spark. At the very minimum invest in a grounded anti static band used for handling sensitive electronic components. Turn off and unplug all non brushless electric motors in the environment, and anything else that could possibly generate a spark. Even toaster arc on the inside when turned on and off. Important info to know if you don't live alone.
As a result of this. Even on a humid summer day where your clothes not only won't, but can't generate static arcs, I still blast outside with at least one barefoot foot on earth or concrete that is in the earth. I have a fine mesh dome I made that I set over the dish as it bubbles away. I move the dish to vacuum once it's done naturally bubbling at stable atmospheric pressure too.
Idk if confirmed but I've heard horror stories of the electric motors in vacuum pumps generating sparks for the impatient as well lol.
Above all else. I blast alone outside. I never allow anyone else to be present when I do. Ever. You cannot be too careful when messing with compressed petroleum gasses. Even when I do it, I'm starkly aware the entire time that I am creating a controlled BLEVE scenario riding on the red line of a genuine explosion as well. Overconfidence can create complacency, which can kill you in this context.