Learn Italian: Ora devo raffreddare lo stampo in acqua fredda. - Now I must cool the mold in cold water.

The verb raffreddare is built directly from the adjective freddo. It combines the prefix ra- (a variation of ri- + a-, indicating a transition or change of state) with the root word to mean "to make cold" or "to cool down."

Why does this sentence use lo stampo instead of il stampo?

Because stampo is a masculine singular noun that starts with an s followed by a consonant (t). In Italian, you must always use the definite article lo (and its plural gli) before masculine nouns starting with s + consonant, z, ps, pn, or gn.

Why is there no preposition like a or di between devo and raffreddare?

Because dovere (must/to have to) is a modal verb. Just like potere (can) and volere (to want), modal verbs connect directly to the following infinitive verb without needing a preposition.

Why do we say in acqua fredda instead of using the articulated preposition nell'acqua fredda?