#fouling

• To foul — To become covered or to cover with a thin or thick layer of residues, carbon deposits, soot, grease, or impurities resulting from thermal or chemical processes; to clog or block due to parasitic deposits. This mechanical phenomenon affects the normal operation of spark plugs, filters, injectors, or other metal parts exposed to incomplete combustion or contaminated fluids.
• Fouling — The act of fouling and its result; a structural process of accumulation and deposition of a layer of carbon deposits, oily residues, soot, or impurities on the inner surfaces of mechanisms or industrial facilities. The phenomenon reduces thermal efficiency, decreases the useful section of pipes, and can cause serious failure of internal combustion engines.
• Fouled — Covered with a dense layer of carbon deposits, oily residues, soot, or impurities resulting from incomplete combustion; the state of a device, filter, or mechanism blocked or partially obstructed by solid deposits. In industrial language, it describes a non-functional or low-efficiency part due to adherent parasitic accumulations.