Cleaning gunk from the river
I am new to this forum but I have been collecting for about 7 years now. The majority of people here tend to dig for their bottles, I snorkel for them in the Charles River. I have always had an issue with a black scale-like substance covering the outside and inside of bottles I fish out. It is easy enough to scrub the outsides of the bottles but i cannot get enough force with a wire brush on the insides to make any meaningful progress. I was wondering if there is a solution I can bathe my bottles in that will help break down this scale. Here are some before and after cleaning photos of a Dr. Swett's root beer I dove for this past Thursday, hopefully that sheds some light on what I am dealing with. I am sorry I do not know why the images are on their side.