fixative vs varnish

fixative and varnish both are nouns.

Word	Noun	Adjective	Verb	Adverb
fixative	Yes	No	No	No
varnish	Yes	No	Yes	No

As nouns, varnish is a hypernym of fixative; that is, varnish is a word with a broader meaning than fixative:

fixative: a varnish dissolved in alcohol and sprayed over pictures to prevent smudging
varnish: a coating that provides a hard, lustrous, transparent finish to a surface

fixative (noun)	varnish (noun)
a varnish dissolved in alcohol and sprayed over pictures to prevent smudging	a coating that provides a hard, lustrous, transparent finish to a surface
a compound (such as ethanol or formaldehyde) that fixes tissues and cells for microscopic study

fixative (verb)	varnish (verb)
	cover with varnish