fixative
From Longman Dictionary of Contemporary EnglishRelated topics: Painting and drawing, Photographyfixativefix‧a‧tive /ˈfɪksətɪv/ noun [countable, uncountable] 1 STICKa substance used to stick things together or to hold things such as false teeth in place2 AVPTCPa chemical used on a painting or photograph so that the colours do not changeExamples from the Corpusfixative• It then glues these thin twigs to a wall using its own saliva as a fixative.