Just like the title says how long should I be vac purging for? When I did my first run I only needed to VAC purge for about 20 minutes or so but this last run I am doing I have been vac purging it for the past three hours and it's still not done? My first run was wax and this seems to be making a Shatter, is it just because it's going to be a shatter? Does shatter take longer to back purge then wax does? I just wanted to know what generally an average amount of time is to be running the vac purge for? It is only around 2 maybe 3 g of oil. I'm not too worried because I doubt you can over purge something LOL.