Now this is a old thread, found by HD google search. Got a good idea, i thought i would like to share with you.
For what it's worth, here is how i clean bottles of unknown origin or with unknown residue in them:
There are many ways to clean for example mason jars.
Mostly you can reach inside and use a scrubbie, which is fine...but what if you can't reach in there and a bottlecleaner brush can't do the job either..?
I have a really nice one gallon glassbottle, i wanted to use when running a strippingrun.
Unfortunatly there was some residue in it..chalk at the bottom and some spots on the sides.
Wrapping my head around how to clean out the gunk i came across yet another good use for foreshots..
Simply put some rice in your bottle and fill foreshots in, seal it.
You don't want to use a corks or similar intended for capping your spirits, as all the disolved gunk will soak into it and contaminate it.
Let it stay in there for half a hour and start shaking it.
The rice will act like grinding material and the foreshots will disolve the gunk inside.
Silica as you know it from the small packages in shoes or whatever they want to protect from moist, also work like a charm.
To my surprise, it even took out the chalk at the bottom...so no need for acetic acid or the like.
Edit: Remember to flush it with dishwasher and water , before use..!