fire flaw
/ˈfʌɪə ˌflɔː/Now rare
noun
A flaw produced by high temperature; a defect that arises during a high-temperature process in the manufacture of something (as the firing of ceramics or the casting of metal objects).
Origin
Late 17th century; earliest use found in William Salmon (1644–1713), medical empiric and author. From fire + flaw.