Originally Posted by popeiam
If you just started your fermentation I don't think it is such a big deal I've heard some people who ferment with out any thing such as a stopper. You could just let it go until you have a chance to get another stopper (quickly as possible/ next day) or if really worried about it you could use tinfoil over the top of the bottle for a day maybe two.
The bad stuff getting in comes from the top kind of falls down. Many people use tinfoil over the neck on of thier starters.
Tinfoil will work on fermentations that last up to 100 years. Bacteria have no means of locomotion, they can only ride the wind currents or fall thanks to gravity. I'll never use an airlock on Apfelwein again, after several successful batches.