Editing Staining (section)

=== Negative staining ===
[[File:HexLamMic phases.jpg|thumb|Example of [[negative staining]]]]
{{main|Negative staining}}
A simple staining method for bacteria that is usually successful, even when the [[#Positive staining|positive staining]] methods fail, is to use a [[negative stain]]. This can be achieved by smearing the sample onto the slide and then applying [[nigrosin]] (a black synthetic dye) or [[India ink]] (an aqueous suspension of carbon particles). After drying, the microorganisms may be viewed in bright field microscopy as lighter inclusions well-contrasted against the dark environment surrounding them.<ref>{{cite book | vauthors = Clark G | date = 1981 | title = Staining Procedures | edition = 4th | location = Baltimore | publisher = Williams & Wilkins | page = 412 | isbn = 978-0-683-01707-6 }}</ref>  Negative staining is able to stain the background instead of the organisms because the cell wall of microorganisms typically has a negative charge which repels the negatively charged stain. The dyes used in negative staining are acidic.<ref name=":1" /> Note: negative staining is a mild technique that may not destroy the microorganisms, and is therefore unsuitable for studying pathogens.