Gas needs a least 2 hours - when bubbles start appearing under the dome, then it flicks off easy. I use a toothpick to clean up around the phosphor but never on the phosphor - I've never seen material left on the phosphor itself. I use a 20x glass with a light built in. If there's stuff in between the wires, it stays there! I'll give it a few good squirts of isop. alcohol to clean it up.
I'm 100% with gas - failed miserably on other methods first.
Gas method thread here: https://budgetlightforum.com/t/-/17374#node-20156