'Wooden', 'cotton', 'gold': saying what things are made of with 'de'
In English you can put a material straight in front of a noun: a wooden table, cotton socks, a gold ring. Portuguese usually can't do that. It names the object first, then adds de plus the material noun: uma mesa de madeira, meias de algodão, um anel de ouro. Literally, it says a table of wood, socks of cotton, a ring of gold.
English speakers trip over this in two ways. They keep the English word order and say something like madeira mesa, or they reach for an adjective that does not exist. Once you know the pattern, it works with almost any material: couro, vidro, plástico, lã and many more.
Word list
nevefA1snowum boneco de neve = a snowmanpapelmA1paperum saco de papel = a paper bagareiafA2sandum castelo de areia = a sandcastlebronzemA2bronzeuma medalha de bronze = a bronze medalcouromA2leathersapatos de couro = leather shoesferromA2ironuma panela de ferro = an iron pangelomA2iceuma escultura de gelo = an ice sculpturemadeirafA2wooduma mesa de madeira = a wooden tablemetalmA2metaluma caixa de metal = a metal boxouromA2goldum anel de ouro = a gold ringpedrafA2stoneuma casa de pedra = a stone houseplásticomA2plasticde plástico = made of plasticpratafA2silverde prata = made of silvervidromA2glassum copo de vidro = a glass tumbleraramemB1wireuma cerca de arame = a wire fencede ouroB1goldencoração de ouro = heart of goldlãfB1woolum casaco de lã = a wool coatsedafB1silkuma blusa de seda = a silk blousetijolomB1brickuma casa de tijolo = a brick houseaçomB2steelde aço = steelalgodãomB2cottoncamisas de algodão = cotton shirtsalumíniomB2aluminiumuma lata de alumínio = an aluminium canbambumB2bamboouma cadeira de bambu = a bamboo chairbetãomB2concreteum muro de betão = a concrete wallborrachafB2rubberbotas de borracha = rubber bootscartãomB2cardboarduma caixa de cartão = a cardboard boxcerafB2waxuma vela de cera = a wax candlecerâmicafB2ceramicum vaso de cerâmica = a ceramic vasechumbomB2leadcanos de chumbo = lead pipescobremB2copperuma panela de cobre = a copper panconcretomB2concreteum muro de concreto = a concrete wallcristalmB2crystalum copo de cristal = a crystal glassgranitomB2graniteuma bancada de granito = a granite worktopmármoremB2marbleuma escada de mármore = marble stairspapelãomB2cardboarduma caixa de papelão = a cardboard boxporcelanafB2porcelainum prato de porcelana = a porcelain plateaço inoxidávelmC1stainless steeltalheres de aço inoxidável = stainless steel cutleryâmbarmC1amberum colar de âmbar = an amber necklaceargilafC1clayum pote de argila = a clay potbarromC1clayum pote de barro = a clay potcortiçafC1corkuma rolha de cortiça = a cork stopperinoxmC1stainless steeluma pia de inox = a stainless steel sinklinhomC1linencalças de linho = linen trousersmarfimmC1ivoryde marfim = made of ivorypalhafC1strawum chapéu de palha = a straw hatpanomC1fabricum saco de pano = a cloth bagplatinafC1platinumum anel de platina = a platinum ringtecidomC1fabricsapatos de tecido = fabric shoeszincomC1zincum telhado de zinco = a zinc roofbarbantemC2twineum tapete de barbante = a twine rugcalcáriomC2limestoneuma parede de calcário = a limestone wallcontraplacadomC2plywoodum armário de contraplacado = a plywood cupboardestanhomC2tinum prato de estanho = a tin plategessomC2plasteruma estátua de gesso = a plaster statuelatãomC2brassuma maçaneta de latão = a brass door handlemadeira compensadafC2plywoodum armário de madeira compensada = a plywood cupboardpergaminhomC2parchmentum manuscrito de pergaminho = a parchment manuscriptresinafC2resinuma cadeira de resina = a resin chairtitâniomC2titaniumum relógio de titânio = a titanium watchveludomC2velvetum vestido de veludo = a velvet dressvimemC2wickerum cesto de vime = a wicker basket
How it works
The pattern is always object + de + material. The material comes after the noun, with no article, and it does not change for number or gender. You say duas camisas de algodão, not algodões, and uma blusa de seda even though blusa is feminine.
Eu comprei uma mesa de madeira.
(I bought a wooden table.)
The same de works after the verb ser, when you describe what something is made of:
Estas cadeiras são de plástico.
(These chairs are plastic.)
Rule of thumb: if the English sentence answers the question "made of what?", use de + material.
The words
Fabrics and clothes
Materials for clothing are the ones you will use most: algodão, lã, seda, couro, linho and veludo. The general words tecido and pano (fabric, cloth) follow the pattern too: sapatos de tecido, um saco de pano.
Prefiro um casaco de lã e sapatos de couro.
(I prefer a wool coat and leather shoes.)
Ela comprou duas camisas de algodão.
(She bought two cotton shirts.)
No verão uso calças de linho e uma blusa de seda.
(In summer I wear linen trousers and a silk blouse.)
Metals
Ouro, prata, ferro, bronze, cobre, aço, alumínio, chumbo, latão, estanho and zinco all work the same way. The phrase de ouro is so common that it is often learnt as one unit.
A minha avó deu-me um anel de ouro.
(My grandmother gave me a gold ring.)
Ele ganhou uma medalha de bronze.
(He won a bronze medal.)
Esta panela é de ferro, por isso é muito pesada.
(This pan is cast iron, so it is very heavy.)
Building and household materials
Here you have pedra, madeira, vidro, mármore, granito, cristal, porcelana, cerâmica, argila and barro (clay), and the two words for concrete: concreto in Brazil, betão in Portugal.
Eles moram numa casa de pedra perto do rio.
(They live in a stone house near the river.)
Pus as flores num vaso de vidro.
(I put the flowers in a glass vase.)
Other materials
Papel, borracha, cortiça, bambu, vime, palha and marfim complete the group. International words that are not in this list, such as poliéster and nylon, follow the same pattern.
Quer um saco de papel ou de plástico?
(Do you want a paper bag or a plastic one?)
Comprei um chapéu de palha para a praia.
(I bought a straw hat for the beach.)
Watch out
Some real adjectives exist
The pattern with de is the safe default, but Portuguese also has a few material adjectives. Plástico can be an adjective (um saco plástico), and there are words like metálico and cerâmico. Be careful with colour words, though. Dourado and prateado mean gold-coloured and silver-coloured. They do not tell you what the object is made of.
Ela tem um relógio dourado, mas não é de ouro.
(She has a gold-coloured watch, but it isn't made of gold.)
Don't add an article
Say de madeira, not da madeira. With an article, the phrase refers to one specific piece of wood.
Same de, different meaning
After a container, de can also give the contents. Um copo de água is a glass of water, while um copo de vidro is a glass made of glass. Context makes it clear.
Dá-me um copo de água, por favor, naquele copo de vidro.
(Give me a glass of water, please, in that glass tumbler.)
Summary
When English puts a material in front of a noun (a wooden table, a gold ring), Portuguese puts it after the noun with de and no article: uma mesa de madeira, um anel de ouro. The material never changes form, and the same phrase works after ser: é de vidro. A few adjectives exist, such as plástico and metálico, but de + material is always correct. Remember that dourado only means gold-coloured.