Non smaltiamo la terracotta finché non termina la prima cottura.

Here, finché non means until.

So finché non termina la prima cottura means until the first firing ends / is finished.

A useful thing to remember is that finché can have slightly different meanings depending on context:

• until
• as long as

In this sentence, it clearly marks the endpoint in time: glazing happens only after that stage is over.

They do different jobs.

• The first non is the real negation:
  Non smaltiamo = We do not glaze

• The second non, after finché, is part of the common Italian pattern finché non = until

So this is not a double negative in the English sense. It does not mean until it does not end. It simply means until it ends.

This second non is often called expletive or pleonastic non: it appears in the structure, but it does not add an extra negative meaning in English.

In this sentence, it is from smaltare.

That matters because:

• smaltare = to glaze / enamel
• smaltire = to dispose of, get rid of, process, work off

The form smaltiamo can belong to either verb, so context is what tells you which one it is. Since the sentence is about ceramics and terracotta, the correct verb here is smaltare.

Smaltiamo is the present indicative, first person plural of smaltare.

Italian often uses we in:

• instructions
• technical descriptions
• workshop procedures
• recipes
• manufacturing processes

So this kind of sentence can sound like a general process rule:
We don’t glaze the terracotta until the first firing is finished.

It does not always mean a very specific group of people standing there right now. It can be a procedural we.

Italian uses the definite article more often than English does.

So la terracotta is normal Italian, even where English might simply say terracotta.

In context, it can mean:

• the terracotta material
• the terracotta pieces being worked on

English often drops the article with materials, but Italian usually keeps it.

Termina is third person singular present indicative.

The subject is la prima cottura.

So, literally, this part means:

the first firing ends

Italian often lets a process or stage be the subject of the verb:

• termina la cottura
• inizia la lavorazione
• finisce l’asciugatura

That is why the verb is singular: it agrees with la prima cottura, not with we.

Because after finché non meaning until, Italian normally uses the indicative when the event is presented as a real, expected point in time.

So:

• finché non termina = normal here

By contrast, if you used prima che, you would normally need the subjunctive:

• prima che termini

A simple way to remember it:

• finché non
  • indicative is very common for until
• prima che
  • subjunctive is the usual pattern for before

In everyday Italian, cottura often does mean cooking or baking.

But in ceramics, it means firing in the kiln.

So la prima cottura is the first firing. In pottery terminology, this is the stage before glazing is applied.

This is a good example of a common Italian word taking a more technical meaning in a specific field.

Italian present tense is often used for:

• general truths
• routines
• instructions
• technical procedures

So this sentence is not necessarily describing only what is happening right now. It can express a standard rule of the process:

We do not glaze the terracotta until the first firing is finished.

That is very natural in Italian. The present tense often does the job that English also uses the present for in manuals and process descriptions.