fixador

Fixador is a noun in Portuguese that designates an agent or device that fixes something in place, stabilizes a condition, or preserves material. The term is used across several fields with different meanings but a common idea: to render permanent or secure.

In photography, the fixador fotográfico, or simply fixador, is a chemical used to dissolve unexposed silver halide in photographic emulsions, thereby halting the development process and making the image stable to light. The most common fixers are ammonium thiosulfate or sodium thiosulfate, usually applied after development and before washing.

In biology and histology, a fixador or fixativo is a chemical that preserves tissue or cells by immobilizing structures and inhibiting decay. Typical fixatives include formaldehyde (often used as formalin), paraformaldehyde, and glutaraldehyde. Fixation preserves morphology and enables subsequent processing for microscopy; the choice of fixative depends on the desired preservation and downstream techniques.

In medicine and orthopedics, a fixador externo, or external fixator, is a device that stabilizes bone fragments from outside the body using pins or wires inserted into the bone. It is used in fracture management, deformity correction, and other indications requiring immobilization.

In textiles and cosmetics, fixadores are agents that help dyes, pigments, or cosmetic products adhere to surfaces or hair. A textile fixative helps dyes withstand washing, while a hair fixador (such as hairspray) provides hold or fixation of hairstyle.

The term thus encompasses several specialized devices and chemicals whose common purpose is to fix, stabilize, or preserve a material or arrangement.