Hi, It's more then 4 years ago since I introduced myself in this post. http://www.apug.org/forums/forum53/13518-greetings-belgium.html The photography time stopped in between and went to renovating our house and getting 2 cute children but I'm up and running again, new darkroom operational including a small still life studio corner for my Linhof. Yesterday I checked the state of my chemicals supply and most of my (glass) bottles have quite some stains inside. So I wondered if there is an efficient way to get rid of that dirt. I figured that shaking them with a water and sand mixture might remove a lot but it's risky if a grain would remain in there and end up in my film tank. Any (chemical) suggestions?