in order to observe their cell characteristics they need to be stained this method consists of preparing a smear that is air dried and heat fixed and adding a stain to the bacteria on the slide. bacteria are very small n transparent when observed with a wet mount preparation. bacteria are usually negatively charged anionic the simple dyes used to stain bacteria have a positive charge cationic they are attracted to each other thee dye molecules r also stringky colored so that our eyes can see the stained bacteria