<P> Most of the dyes commonly used in microscopy are available as BSC - certified stains . This means that samples of the manufacturer's batch have been tested by an independent body, the Biological Stain Commission (BSC), and found to meet or exceed certain standards of purity, dye content and performance in staining techniques . These standards are published in the Commission's journal Biotechnic & Histochemistry . Many dyes are inconsistent in composition from one supplier to another . The use of BSC - certified stains eliminates a source of unexpected results . </P> <P> Some vendors sell stains "certified" by themselves rather than by the Biological Stain Commission . Such products may or may not be suitable for diagnostic and other applications . </P> <P> A simple staining method for bacteria that is usually successful, even when the "positive staining" methods detailed below 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 . Note: negative staining is a mild technique that may not destroy the microorganisms, and is therefore unsuitable for studying pathogens . </P> <P> Gram staining is used to determine gram status to classify bacteria broadly . It is based on the composition of their cell wall . Gram staining uses crystal violet to stain cell walls, iodine as a mordant, and a fuchsin or safranin counterstain to mark all bacteria . Gram status is important in medicine; the presence or absence of a cell wall changes the bacterium's susceptibility to some antibiotics . </P>

Could any dye available in the microbiology lab be used in place of nigrosin for negative staining