We study sugars in organic chemistry. Put sugar in my coffee. The papers were stacked on the table. We wrote on paper. When a non-count noun is used to classify something, it can be treated as a count noun.
Chilean wines are superb.
Ideas for the above tables are based on material found in A University Grammar of English by Randolph Quirk and Sidney Greenbaum. Used with permission. Examples our own. We recommend, also, that you refer to our section on Articles and Determiners for additional review of the words that modify and quantify nouns.