La barbotine sert à coller les colombins.

Sert à means is used for or serves to.

It comes from the verb servir. In this sentence, La barbotine sert à coller les colombins means that the slip has the function of sticking the coils together.

A very useful pattern is:

quelque chose sert à + infinitive
= something is used to + verb

For example:

• Un couteau sert à couper. = A knife is used for cutting / is used to cut.
• La colle sert à fixer le papier. = Glue is used to attach paper.

Because sert is the 3rd person singular present tense form of servir.

The subject is La barbotine, which is singular, so French uses:

• je sers
• tu sers
• il / elle / on sert
• nous servons
• vous servez
• ils / elles servent

So:

• La barbotine sert... = The slip serves / is used...

Be careful: serve does exist, but it is a different form, such as in the subjunctive:

• Il faut qu’elle serve...

Because the expression is servir à + infinitive.

French often uses a preposition before an infinitive, and with servir meaning to be used for, the required preposition is à.

So:

• servir à faire quelque chose = to be used to do something

Examples:

• Cette machine sert à couper le bois.
• Une éponge sert à nettoyer.

You cannot normally remove the à here. Sert à coller is the standard structure.

Because after sert à, French uses an infinitive to express the action the thing is used for.

So the structure is: subject + sert à + infinitive

Here:

• sert à coller = is used to stick / glue

This is similar to English:

• It is used to attach
• It serves to hold

So coller stays in its basic dictionary form, not a conjugated form.

Here, coller means to stick, to glue, or to join by making things adhere.

In pottery vocabulary, it does not necessarily mean using commercial glue. It refers to making two pieces of clay stick together. That is why barbotine is used: it helps bond the clay pieces.

Some common uses of coller:

• coller deux morceaux = to stick two pieces together
• coller une affiche au mur = to stick a poster on the wall
• ça colle = it sticks / it’s sticky

So in this sentence, coller les colombins means to join the coils together.

La barbotine is a feminine noun. In pottery, it usually means slip: a liquid mixture of clay and water used to join pieces of clay or for decoration.

That explains why the sentence uses la:

• la barbotine

This is specialized vocabulary, so learners may not see it often outside ceramics or pottery contexts.

Les colombins are coils of clay used in pottery.

The singular is:

• un colombin

The plural is:

• des colombins
• or les colombins when referring to specific coils

In coil pottery, you build a form using long rope-like pieces of clay, and la barbotine helps attach them to one another.

Les is the definite article, so it means the coils. It refers to specific coils already understood from the context.

French often uses the definite article where English might be less specific.

Compare:

• coller les colombins = stick the coils / join the coils
• coller des colombins = stick some coils

In a pottery instruction context, les colombins makes sense because the speaker is talking about the coils being used in that process.

A careful pronunciation would be approximately:

La barbotine sert à coller les colombins
lah bar-bo-TEEN sair ah koh-LAY lay koh-lom-BAN

A few notes:

• sert sounds like sair
• à coller links smoothly in speech
• les sounds like lay
• colombins ends with a nasal sound, so the final s is silent

The exact pronunciation will vary by accent, but the important points are that many final consonants are silent and colombins has a nasal ending.

Because coller already implies making things stick or join. In context, coller les colombins naturally means to stick the coils together.

French often leaves some information to context when the meaning is obvious. If needed, French could be more explicit, for example:

• coller les colombins entre eux = stick the coils to each other

But in a pottery context, coller les colombins is enough.

It is mostly neutral but technical because of the pottery vocabulary:

• barbotine
• colombins

The grammar itself is very ordinary and useful:

• X sert à + infinitive

So even if the vocabulary is specialized, the sentence structure is common and worth learning.