what is a good steep, as in how, let sit capped, un cap? and i installed a fresh coil to swap the flavor...
well... you will get a lot of debate from different people about this.
Essentially though, you want to really shake your juice, till you see tiny air bubbles in it, then let it sit uncapped till all those air bubbles are gone, repeat that a few times. The put it in a dark cool place for a week or two, shaking it every few days.
Most "good" juice vendors send their juice out pre-steeped, smaller operations and Brick and Mortar shops that make their own, often dont have the time or space to allow the juice to steep.
Basically what you are doing, is letting the flavors mingle with the PG/VG and the alcohol or other solvent that those flavoring liquids are in, to dissipate.
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For myself, I am always buying juice that I plan to smoke in a month, not tomorrow.