Color changing liquids

[champions]

So I was running low on the tobacco flavor I made that I really liked. So I decided to make another batch exactly like the first. I still had a bit of the old left and when put side to side the new batch looked a lot lighter than the first. Today however the colors are a bit closer. I'm guessing tomorrow they will match.

Why?

 

[Liv2Ski]

What color bottles. If you base liquid is in blue or brown you have limited the uv light exposure. The flavor you mixed is pobably clear bottle UV will produce slight color changes

 

[RIMP]

I believe it has to do with the flavors and nic melding. I have several of the same flavors, in varying nic levels, and the higher nics are darker in color.
RIMP

 

[Nikhil]

Small percents of nicotine exposed to oxygen turn to cotinine, which is very dark (it is the same thing your body metabolizes nicotine into). Your old bottle has just had more oxygen and time, and heat/light to accelerate the process.