I tried making my own vanilla extract a few months ago. Normally, it should be pretty dark (almost black). Mine isn't, as you can see:
What I did was (after sterilizing it) filling a 250 ml (about a cup) bottle with vodka. I also cut up some (mostly seeded) vanilla pods, I think 4-5.
My guess is that there isn't enough vanilla in it. I'm planning on putting some more in. Is that the proper way to save this half-extract? Are there any downsides to adding new pods now?
You can definitely improve the extract by adding more vanilla beans to the bottle as well as allowing the alcohol more time to extract the vanilla essences from the beans. Most references I have seen say you need to allow at least 2 months with daily agitation to get decent extraction. You can leave the beans in the alcohol as long as you want, but the vast majority of extraction is complete after 6 months.
As a guideline to start from, in the US the FDA requires anything labeled as vanilla extract to have at least 13.35oz (380g) vanilla beans per gallon (3.8L).
I can't think of any downsides to adding more. The recipe I use calls for at least 8 beans per cup (more is better).
Usually it's recommended to cut the beans in half and scrape out the seeds, adding both the beans and the seeds to the vodka - at least, this is what I do, and I think it probably allows more flavor to be extracted.
