Learn Hardcore German: Mein dunkelblaues T-Shirt ist voller Sand, deshalb klopfe ich es aus. - My dark-blue T-shirt is full of sand, therefore I dust it off.

dunkelblaues is the adjective dunkelblau (“dark blue”). In German, adjectives placed before a noun must be declined. Here it modifies the neuter, singular noun T-Shirt in the nominative case and follows the possessive pronoun mein. Possessives trigger the “mixed” declension, so for neuter nominative singular the adjective takes the -es ending.

Why is T-Shirt capitalized and what gender is it?

All German nouns are capitalized. T-Shirt is a borrowed word treated as a noun in German and is neuter: das T-Shirt. That’s why you say mein dunkelblaues T-Shirt.

Which case is Mein dunkelblaues T-Shirt in?

It’s in the nominative case because the phrase functions as the subject of the sentence: “Mein dunkelblaues T-Shirt ist voller Sand.”

Why is voller Sand used here instead of something like mit Sand voll?

The adjective voll (“full”) can take a noun in the genitive without a preposition, yielding voller Sand (“full of sand”). Grammatically, voll is treated like an adjective before its noun and takes the strong genitive ending -er (masculine/neuter). You could also say mit Sand voll or mit Sand gefüllt, but voller Sand is more concise and idiomatic.

Shouldn’t Sand get an -s or -es in the genitive?

Typically masculine/neuter nouns add -s/-es in the genitive (e.g. des Sandes). In the set expression voller Sand, the ending on Sand is often dropped—especially with mass nouns—because the meaning “full of sand” is clear without it.

What does deshalb mean and why is it at the beginning of the second clause?

deshalb means “therefore” or “so.” It’s a sentence‐adverb (also called a conjunctive adverb). When it occupies the first position in a main clause, German requires verb-second word order. Thus you get Deshalb klopfe ich es aus.

Why does aus appear at the end of klopfe ich es aus?

The verb here is ausklopfen (“to knock/beat out”). In German, many verbs have separable prefixes (such as aus-, mit-, an-). In main clauses the prefix detaches and moves to the end of the clause. The finite verb klopfe stays in second position, and aus goes to the very end.

What does es refer to in klopfe ich es aus?

The pronoun es is the direct object of ausklopfen and refers back to das T-Shirt. In German you use es to replace a neuter noun.