What Marine-Grade Actually Means for Outdoor Furniture
What does marine-grade mean for outdoor furniture?
Marine-grade means a material or finish specified to survive constant salt, moisture and sun without corroding, fading or failing. For aluminium furniture it covers three things: the alloy of the tube, the coating system on top of it, and the fittings that hold it together. A piece is only as marine-grade as the weakest of the three. The phrase has no legal definition in Australia.
Does aluminium outdoor furniture rust?
No. Rust is iron oxide, and aluminium contains no iron. Bare aluminium reacts with air to form a hard, thin layer of aluminium oxide that seals the surface. What aluminium can do is develop a chalky white bloom in salt spray, or filiform corrosion if a powder coat is chipped through to bare metal.
What alloy should marine-grade aluminium be?
Furniture frames are almost always extruded tube, and the 6000 series alloys (6061 and 6063) suit it well: strong for their weight, weld well and resist corrosion once coated. More useful than the alloy number is the wall thickness of the tube. Quality frames use tube around 1.5 to 2mm thick and do not flex under a firm push.
What makes a powder coat marine-grade?
The difference between a coat that looks new at ten years and one that is chalking at three sits in four places: pre-treatment before coating, film thickness (a marine specification runs to about 60 to 80 microns), the resin (exterior-grade polyester holds colour; cheaper epoxy chalks), and cure.
What is salt-spray testing, and does it prove anything?
The standard test for coatings in a salty environment is ASTM B117, the neutral salt spray test. It is an accelerated test that separates coating systems reliably, though it is not a promise of years. We're currently confirming the specific test results and coverage for our aluminium ranges with our supplier, and will update this article once that is in hand. Ask any retailer whether their frames have been salt-spray tested; most have never been asked.
What fittings should marine-grade furniture use?
Every screw, bolt, glide and hinge should be either stainless steel or aluminium. Zinc-plated mild steel screws weep rust down a powder-coated leg within a year on the coast. Grade 316 stainless resists the chloride attack that salt air delivers; Grade 304 will serve further inland but can tea-stain near the surf.
Is there marine-grade rope and fabric?
The rope woven across our ranges is solution-dyed polypropylene and polyester: the colour is in the fibre itself, and it is hydrophobic, so it does not absorb water and does not grow mould. It holds its colour well for years in full Australian sun. For fabric the equivalent phrase is solution-dyed, which is how all of our cushion covers are made.
How do I look after marine-grade aluminium furniture?
Within a kilometre of breaking surf, hose the frames with fresh water every couple of weeks and wash with mild soapy water monthly. Further inland, a soapy wash twice a year is plenty. Touch up any chip through to bare metal the week you find it. The complete care guide covers every material in the catalogue.
Questions that expose the pretenders
What alloy is the frame, and how thick is the tube wall?
What pre-treatment is applied before the powder coat, and how thick is the coat?
Has the coating system been salt-spray tested, and to how many hours?
Are the screws and bolts 316 stainless, 304 stainless or plated steel?
Is the rope solution-dyed?
What does the warranty say about coastal use?
What Sissonne Outdoor uses
Our aluminium-framed ranges use powder-coated aluminium frames with stainless or aluminium fittings, solution-dyed rope or ECOLENE® synthetic wicker, and solution-dyed fabric covers over quick-dry foam. How long each material lasts is covered in our lifespan guide. The warranty is a 24-month manufacturer's warranty for domestic use, excluding fair wear and tear; commercial use is assessed case-by-case. Both showrooms, in Hawthorn and Southport, keep frames you can press, lift and turn over.
FAQ
Is powder-coated aluminium good for coastal areas? Yes, when the coating system is a marine specification and the fittings are stainless or aluminium. Rinse with fresh water every few weeks near the surf.
What is the white powder on my aluminium furniture? Aluminium oxide, sometimes called white rust, forming where bare metal meets salt air.
Is 304 or 316 stainless steel better for outdoor furniture? 316 for coastal homes; 304 is fine inland but can tea-stain near the sea.
Is marine-grade aluminium furniture heavy? No. Aluminium is about a third the weight of steel.
