Some people suggest using gravel to clean the inside of irregular shaped bottles, but it will scratch the glass. It is not something that you would want to use to remove debris from the inside of an antique. Other methods are safer and work just as well. My former mother-in-law bought and sold antiques, and she used these easy cleaning techniques. Her glass pieces turned out crystal clear.
Cleaning Away Years of Grime
Begin with a White Vinegar and Water Soak
If the inside of a bottle is cloudy, try soaking it in a mixture of half white vinegar and half warm water. Allow it to soak inside and outside of the glass overnight or for several hours. The vinegar will help to loosen and remove mineral deposits that were caused by hard water. It will also work to loosen dirt and other debris. However, do not use it on antique glass bottles that are painted or gold-trimmed. Vinegar is naturally acidic, and it can cause irreparable damage to delicate surfaces. When in doubt, test it on a small inconspicuous area of a bottle before soaking it for hours on end or cleaning an entire piece.
Use Raw White Rice, Dish Soap and Hot Water
As previously mentioned, small rocks are often suggested when attempting to clean the interior of antique glass bottles. Use something just as effective but much safer instead. Add an inch or two of uncooked rice (not instant) to the bottom of the dirty container. Fill it halfway with hot water and a drop or two of dish soap. Cover the bottle and shake it vigorously for a few minutes or until the stains loosen. The rice will gently scrub areas that cannot be reached with a rag, and it will not damage old glass.
Aquarium Brushes are Ideal Bottle Cleaning Tools
When old glass bottles are far too dirty inside for white vinegar or rice, pick up an aquarium brush from a local pet supply store. They are ideal for the job since the handles bend very easily. The bristles are soft but durable, and they will reach areas that no other tool or rag could reach. Use hot soapy water and an aquarium brush of the appropriate size to scrub away years of grime. If necessary, follow up with water and white vinegar soak. Old bottles can look as good as they did when they were new.