Oddzielaj metal od tworzyw sztucznych.

Both are imperatives, but they come from different aspects:

• oddzielaj → from oddzielać (imperfective)
• oddziel → from oddzielić (perfective)

In Polish, the imperfective imperative is often used for:

• general instructions
• repeated actions
• habits
• rules on signs or labels

So Oddzielaj metal od tworzyw sztucznych sounds like:

• separate metal from plastics (as a general rule)
• keep metal separate from plastics

By contrast, Oddziel metal od tworzyw sztucznych sounds more like a one-time command: separate it now.

For public instructions, oddzielaj is very natural.

Oddzielaj is the 2nd person singular imperative, so literally it addresses you in the singular, informally.

But on signs and instructions, Polish often uses this form in a generic way, not because the speaker is being informal with one specific person. It works like a general instruction to anyone reading it.

Other possible forms would be:

• oddzielajcie — plural you
• proszę oddzielać — more formal, impersonal
• należy oddzielać — very official/impersonal

So here, oddzielaj is just a normal instruction style.

Metal is in the accusative singular.

The verb pattern is:

• oddzielać coś od czegoś
• oddzielić coś od czegoś

So:

• co? → metal
• od czego? → od tworzyw sztucznych

Because metal is an inanimate masculine noun, its accusative singular looks the same as its nominative singular:

• nominative: metal
• accusative: metal

That is why the form does not change.

Because the preposition od takes the genitive case here.

The structure is:

• oddzielać coś od czegoś = to separate something from something

So:

• metal = the thing being separated
• od tworzyw sztucznych = from plastics

The noun tworzywa changes to the genitive plural tworzyw, and the adjective sztuczne changes to sztucznych to match it.

It is the genitive plural of tworzywa sztuczne.

Base form:

• singular: tworzywo sztuczne
• plural: tworzywa sztuczne

Meaning:

• plastic material
• plastics

In everyday English, you would usually translate tworzywa sztuczne simply as plastics.

Literally, the phrase means something like artificial materials, but in normal usage it refers to plastics.

Because tworzywa sztuczne is a more standard and formal term, especially in technical, official, or recycling contexts.

Compare:

• plastik — common everyday word, often informal
• tworzywa sztuczne — more precise/formal, very common on labels, instructions, and sorting guidelines

So on a sign or instruction, tworzywa sztuczne often sounds better and more official.

Because metal is being used as a material category, not as a countable list of different metals.

In recycling and sorting language, Polish often uses singular material nouns this way:

• papier
• szkło
• metal
• plastik

So metal here means metal items / metal as a type of waste/material.

Using metale would suggest different kinds of metals, which is not the usual wording for a sorting instruction like this.

The dictionary form is tworzywo.

Here is the basic pattern:

• singular nominative: tworzywo sztuczne
• plural nominative: tworzywa sztuczne
• plural genitive: tworzyw sztucznych

So in the sentence, tworzyw is an inflected plural form of tworzywo.

Because tworzywa sztuczne is a fixed, conventional expression in Polish.

Although Polish often puts adjectives before nouns, some combinations are standard with the adjective after the noun, especially in established terms and classifications.

So:

• tworzywa sztuczne is the normal term for plastics
• sztuczne tworzywa is possible grammatically, but it does not sound like the standard name of the category

This word order stays the same when the phrase is inflected:

• od tworzyw sztucznych

Yes. Polish word order is flexible, so you could also say:

• Metal oddzielaj od tworzyw sztucznych.

That still means the same thing.

However, Oddzielaj metal od tworzyw sztucznych sounds very natural for an instruction, because starting with the verb is common in commands and procedural language.

So the given order is a very normal choice.

A rough English-style guide is:

• oddzielaj ≈ od-JE-lai
• metal ≈ ME-tal
• od ≈ ot
• tworzyw ≈ tfo-ZHIWF
• sztucznych ≈ SHTOOCH-nihkh

A smoother full approximation:

od-JE-lai ME-tal ot tfo-ZHIWF SHTOOCH-nihkh

A few useful notes:

• dz in oddzielaj is pronounced like j in jam
• rz in tworzyw sounds like zh
• szcz in sztucznych is a difficult cluster for English speakers; it begins with a sh-like sound
• Polish stress is usually on the second-to-last syllable:
  • oddzieLAJ
  • MEtal
  • twoRZYW
  • sztuczNYCH

Yes, it is natural, especially in formal or instructional Polish.

It sounds like something you might see in:

• sorting instructions
• waste disposal guidelines
• educational materials
• public signage

Depending on style, you might also encounter similar phrases such as:

• Oddziel metal od plastiku.
• Segreguj metal oddzielnie od tworzyw sztucznych.
• Nie mieszaj metalu z tworzywami sztucznymi.

But the original sentence is absolutely correct and natural.