Dirty bottles found

[spectrum]

I have been having some luck finding old bottles with painted letting on them. Being in the silt at the bottom of ponds they tend to have brown stains. Meanwhile decades of immersion seems to have broken down the binder in the paint and it is easily disturbed. I'm looking for tips and tricks to clean and preserve these items.

Thanks,
Pete

 

[markfm]

This site might be handy:
http://www.antiquebottles.com/cleaning.html