Is there a possibility of having "hot spots" in say, a bottle of VG-base nic liquid, because the liquid wasn't homogenous? I heard that Chris at My Freedom Smokes preferred to limit the strength of his VG nic for that reason.
What if a vendor added nic to a bottle, filled it up with base, capped and shipped it. No stirring, no agitation. Would a high proportion of the nic end up on top?
/ speculation
I believe that would be possible. This is why people need to know what they are doing when they mix nicotine. I'm not sure if the nicotine would fall to the bottom or be at the top, but it's possible that there would be a gradient of nicotine concentration.
In pharmaceuticals, this is an issue (think of all the components in Nyquil as an example). The person/company mixing the liquid needs to have procedures in place to test the mixing of the components. Even with solid samples (pills) mixing is a crucial step that has to be monitored. I know that companies that make pills and liquids have SOPs (standard operating procedures) for testing these things. Like they will take samples from the top, middle, and bottom of a vat and test them to make sure they are all homogenous. The difficulty in mixing nicotine is not an excuse for sending out poorly mixed product.