After brewing my latest lambic batch I boiled down some of the extra second runnings with a little bit of aged hops and stuck the pot in my semi-enclosed sunroom. The room is almost entirely enclosed with glass but with a few openings to the outside that air/water/bugs can easily come through. I've tried setting out second runnings a couple times before and always ended up with mold so I wasn't too optimistic but thought it worth another try.
I managed to entirely forget about the pot for a week and just happened to see it again when I walked into the room to water some plants. Bringing it inside I saw that it appeared to have a little gunk on the bottom but nothing growing on top and it smelled vaguely fruity and a bit cider-like. I made my standard starter addition size (1/2 cup DME in 1 pint water) and added most of the pot to the starter in a 1 gallon carboy while reserving a vial's worth in case the starter had issues and I wanted to be able to try stepping it up again later.
The starter hasn't seemed to change at all in a few weeks so I decided to give it gravity and taste tests. Gravity is down to 1.004 (from approximately 1.040) and tastes and smells slightly sweet, fruity and lightly tart, giving the same cider impression as when I first pulled the pot inside.
It's hard to tell what I really have on my hands or what to do with it. There is clearly yeast and there doesn't seem to be any other bugs but what strain(s) of yeast I'm dealing with is hard to tell without doing some streaking and testing (even then I wouldn't know much more about the strains than very high level info without using them individually), which may or may not be worth doing in the end.
One use might be to toss this in with other commercial bugs and let it do its thing alongside them for a lambic. Another option would be to brew a straightforward beer (probably Saison) and see how it plays out on its own. For now I'll probably just hold onto it until something comes to me.
Still pretty sweet and fruity, decided to add it to my lambic to give it a little more complexity and sugars to chew on.