If I was intending to speed up oxidation of my nic concentrate, I would:
- use LDPE bottles, as they are the most porous
- open and use some periodically, introducing more and more oxygen
- keep it at room temperature, allowing plenty of molecular activity
That's what I did with my first 120ml bottle of nic I bought from Good Prophets in 2012. It was brown/amber within about nine months.
I've used full bottles, non-ldpe plastic and glass, stored in the freezer ever since. Virtually no tint, smell or taste after three+ years.
Based on what I've seen in Rossum's experiment as well as Kurt's thoughts, temperature is the primary issue, the colder the better. Headroom and container porosity are next, then light.