An image produced using silver and mercury is called which process?

• A. Daguerreotype
• B. Calotype
• C. Ambrotype
• D. Collodion

Answer: (A)

The daguerreotype is the process that uses silver and mercury to create an image. It starts with a polished silver-coated copper plate that is sensitized and exposed to light; after exposure, mercury vapor develops the latent image, forming a silver–mercury amalgam that shows as a direct-positive picture on the plate. This combination of silver with mercury development is distinctive to daguerreotypes, producing exceptionally sharp, highly detailed images without a negative. By contrast, the calotype relies on silver iodide on paper and yields a negative; the ambrotype uses a glass plate with a collodion-based negative viewed against a dark backdrop to appear positive; and collodion generally refers to the wet-plate process that involves iodized collodion, not the silver–mercury development used in daguerreotypes.