The most common fixative is formalin (10% neutral buffered formaldehyde in water). It is usually used as a 10% neutral buffered formalin (NBF), that is approx. During this investigation inflammatory pain was induced on rats using formalin. These reduce silver solution to metallic silver after formalin fixation. Some wastes are considered "multihazardous," such as tissue samples preserved in formalin. "Argentaffin cells" reduce silver solution to metallic silver after formalin fixation. They can also be used to detect some antigens masked by formalin. Cells are cross-linked by UV or formalin and nuclei are isolated from these treated cells. An example of this would be hydroquinone or formalin. The black cub was preserved in formalin. Contact sensitization is increased, especially with formalin. In addition to formalin, other chemical fixatives have been used. Its effects are reversible by excess water and it avoids formalin pigmentation. Nina left to concentrate on photography and eventually form the band Formalin. Formalin fixation can also leave a brown to black pigment under acidic conditions.