Editing Spark plug (section)

====Seals====
Because the spark plug also [[seal (mechanical)|seals]] the combustion chamber of the engine when installed, seals are required to ensure there is no leakage from the combustion chamber. The internal seals of modern plugs are made of compressed glass/metal powder, but old style seals were typically made by the use of a multi-layer [[brazing|braze]]. The external seal is usually a [[crush washer]], but some manufacturers use the cheaper method of a taper interface and simple compression to attempt sealing.