Outdoor Furniture: Understanding Materials, Caring Properly, Overwintering Well

Teak (Tectona grandis) owes its reputation to two properties: a solid density (around 0.67 at twelve percent wood moisture) and above all its natural wealth of oil and resin, which protects the wood from within against moisture and fungi. The honest nuance that often gets lost in the furniture trade: the research institute CIRAD rates teak's durability against fungi in classes 1 to 3 – “very durable to moderately durable, depending on the origin and age of the stands”. Old forest teak reaches the top class; today's market, however, consists almost entirely of plantation teak, whose durability varies more strongly. For buying, that does not mean “hands off”, but rather: ask about the origin and quality of the teak – reputable manufacturers will provide that information.

Why does teak – like any untreated wood – turn grey outdoors? Wood research has described the mechanism cleanly: UV light photochemically breaks down the lignin in the outermost layer of wood, about one to two millimetres thin; rain washes out the soluble degradation products, and what remains are the lighter cellulose fibres – the characteristic silver-grey patina. The decisive point: the process is purely superficial and does not materially impair the substance. Greying is therefore a question of taste, not a damage report. If you prefer the honey-coloured as-new state, clean the wood periodically and treat it with teak oil or teak protector – a widespread manufacturer recommendation that means work and is motivated purely by looks. If you like the patina, you need to do nothing at all.

Both metals are reliable outdoors, but for different, well-documented reasons. Aluminium (density 2.70 g/cm³ – which is why it is so pleasantly easy to move around) forms of its own accord in air a microscopically thin oxide layer that protects the surface against further corrosion; the powder coating customary in furniture making – electrostatically applied, baked-on polyester powder – lays an additional, colour-giving protective skin over it (process description, trade convention). Stainless steel works differently: from a good 10.5 percent chromium content, a passive, chromium-rich oxide layer forms, which renews itself on contact with oxygen – scratches “heal” chemically. Neither of the two materials is better across the board: aluminium scores with its low weight and variety of colours, stainless steel with robustness and its self-healing surface. The one care rule applies to both: mild soapy water instead of scouring agents, so that the protective layers remain intact.

With outdoor cushions and covers, the dyeing technique decides how long the colour lasts: in solution-dyed acrylic fibres, the pigment sits in the fibre mass itself, not just on the surface – the established quality convention for colour-fast outdoor textiles. Colour fastness can be measured through standardised test methods: ISO 105-B02 tests light fastness under xenon light, ISO 105-B04 fastness under artificial weathering with rain spray – anyone comparing fabric qualities may ask about these test values. As for weave, UV-stabilised HDPE synthetic wicker has established itself as today's standard for high-quality furniture (trade convention): insensitive to moisture and dimensionally stable – permanent point loads, however, are not to its liking.

The largest part of outdoor care is proven practical knowledge – and we label it as such: