Use an article or other determiner if you are referring to one or all of a noun. If you decide an article is necessary, you must then choose an appropriate article. Singular countable nouns always refer to a specific amount (one), so they always require an article (unless another determiner is present).
Iridescent quality in many lipsticks is created by blend of fish scales
from commercial fish-packing companies.
The iridescent quality in many lipsticks is created by
a blend of fish scales from commercial fish-packing
companies. [Quality and blend are both countable
nouns, so in the singular, they must be preceded by an article.]
--"Take It or Leave It," Valley Comic News (modified)
Plural countable nouns and uncountable nouns require an article if they refer to a specific group or subset of the noun. A specific group might be all of the noun in existence, a noun that is modified by a prepositional phrase or a relative clause, or even an unmodified noun that is understood as referring to a specific group or subset of the noun.
Motion sickness occasionally suffered by two out of five astronauts has
been labeled astronausea.
The motion sickness occasionally suffered by two out of
five astronauts has been labeled astronausea. [The phrase
occasionally suffered . . . identifies the
specific subset of the uncountable noun motion sickness.]
--"Take It or Leave It," Valley Comic News
