opacifier
Noun
Meaning
(chemistry) a chemical agent added to a material, such as rocket propellant, to make it opaque
(figuratively) an extraneous agent or vehicle which, intentionally otherwise, makes something opaque
Source: en.wiktionary.orgSynonyms
Examples
Applications Sand-sized grains of zircon Zircon is mainly consumed as an opacifier, and has been known to be used in the decorative ceramics industry.
Its main use is as an opacifier, conferring a white, opaque appearance to ceramic materials.