Filtrikihiga

Filtrikihiga refers to a specific type of historical layered filter, primarily found in the context of early photography and chemical processes. These filters were not the electronic or digital filters common today, but rather physical arrangements of materials designed to selectively transmit or block certain wavelengths of light or to purify liquids. The term itself is Estonian, where "filtri" means filter and "kihiga" signifies layered or with layers.

Historically, these filters were often constructed using multiple strata of absorbent materials like charcoal, sand, or fine gravel. The effectiveness of a filtikihi depended on the pore size, the specific properties of each layer, and the order in which they were arranged. In photography, they were used to control the exposure of light-sensitive emulsions, influencing contrast and color rendition. Beyond photography, similar layered filtration principles were applied in early scientific experiments, particularly in chemistry and brewing, to remove impurities from solutions or air. The concept of a filtikihi highlights an early understanding of physical separation and selective transmission that predates modern scientific terminology and technologies.