O vidrado endurece, ao passo que o púcaro racha.

Ao passo que is a connector that introduces a contrast. In this sentence, it works like:

• whereas
• while
• by contrast

So it is not mainly about time here; it is about two different things happening in opposition or contrast.

It is a fairly standard expression, but it can sound a bit more formal or written than simpler connectors like mas.

The comma separates the two clauses:

• O vidrado endurece
• ao passo que o púcaro racha

With a contrastive linker like ao passo que, the comma is very natural and standard. It helps show that the second clause is being set against the first one.

Here, vidrado is a noun, not an adjective. It means the glaze or glazed coating on a ceramic object.

This word can be confusing because vidrado can also be:

• an adjective meaning glazed or glassy
• in other contexts, something like obsessed or crazy about, especially with em

But in this sentence, it is clearly the ceramic glaze.

Púcaro is a noun for an earthenware vessel, clay pot, or small ceramic jug/pot.

For many learners, it feels like a less everyday word. It is not one of the most basic household nouns in modern speech, and it may sound literary, traditional, or tied to pottery/ceramic contexts.

So yes, it is a real word, but not necessarily one you hear every day in casual conversation.

They are in the present indicative because the sentence states a general fact or a typical process.

Portuguese often uses the present tense for:

• general truths
• scientific or technical descriptions
• habitual processes

So this is like saying what normally happens under certain conditions, not what happened one single time in the past.

• endurece = hardens, becomes hard
• racha = cracks, splits

A useful nuance:

• endurecer focuses on becoming firm or hard
• rachar suggests a crack opening or the object splitting

So racha is more specific than a general verb like quebra. Something that racha develops a crack; it does not necessarily shatter completely.

Portuguese uses the definite article much more often than English, including in general statements.

So:

• o vidrado
• o púcaro

can refer to the material or object in a general or class-level way, not only to one uniquely identified item.

English often drops the article in this kind of statement, but Portuguese commonly keeps it.

Sometimes yes, but the nuance changes.

• enquanto can also mean while, but it often has a stronger time-related sense
• mas simply means but, which is less precise here

So:

• O vidrado endurece, enquanto o púcaro racha
  possible, but it may sound a bit more temporal or less formal

• O vidrado endurece, mas o púcaro racha
  grammatical, but weaker and less elegant if you want a clear contrast

Ao passo que is a good choice when the point is a structured contrast between two parallel processes.

A simple pronunciation guide:

• vidrado → stress on dra: vi-DRA-do
• púcaro → stress on pú: PU-ca-ro
• racha → stress on the first syllable: RA-cha
• ch in racha sounds like sh in ship

A few helpful notes:

• The accent in púcaro shows the stress clearly: PÚ-caro
• In European Portuguese, unstressed vowels are often reduced, so the actual sound can be less open and less full than an English speaker expects

Yes, the sentence can be rearranged, for example:

• O púcaro racha, ao passo que o vidrado endurece.

This is still grammatical. The main difference is emphasis: now the sentence starts by focusing on o púcaro instead of o vidrado.

The original version feels balanced and natural, especially if the speaker wants to present the hardening of the glaze first and then contrast it with the cracking of the pot.