Real Dictionary

fixative
variable noun: Fixative is a liquid used to preserve the surface of things such as a drawings or photographs.

fixative in American English
a substance that makes something permanent, prevents fading, etc., as a mordant or a preservative used in microscopy
that is able or tends to make permanent, prevent fading, etc.
adjective: serving to fix; making fixed or permanent
noun: a fixative substance, as a gummy liquid sprayed on a drawing to prevent blurring, or a solution for killing, hardening, and preserving material for microscopic study

fixative in British English
adjective: serving or tending to fix
noun: a fluid usually consisting of a transparent resin, such as shellac, dissolved in alcohol and sprayed over drawings to prevent smudging