Most people choose a shade sail by shape, size and colour, and that makes sense: those are the things you see. But the shade sail fabric is what you live with every summer. It decides how the sail handles a passing shower, how much air moves through it, how it should be tensioned and how you look after it. This guide explains, in plain English, what "Oxford polyester with a PU coating" actually means, how it compares with the knitted shade cloth you see on many Australian sails, and how to get the most from a coated fabric at home. If you're still at the planning stage, start with our guide to choosing your shade sail, then come back here for the detail on fabric.
What shade sail fabric is made of
Walk through any Australian suburb and you'll see two broad families of shade sail fabric.
- Knitted shade cloth. Usually made from a polyethylene yarn knitted into an open mesh. You can see light through it, and air passes through the small gaps in the knit.
- Woven, coated fabric. A polyester yarn woven into a tight cloth, then coated on one side. The coating closes the weave, giving a tight, solid-looking cloth rather than an open mesh.
Neither family is right for every backyard. They simply behave differently, and knowing the difference helps you choose, install and care for your sail properly.
All the sails in our shade sail range belong to the second family: they are made of 100% polyester Oxford fabric with a PU coating.
Oxford polyester explained
"Oxford" sounds like a brand, but it isn't. It's the name of a weave, the way the threads cross each other.
The weave
In an Oxford weave, the threads are grouped and woven over and under each other in a simple basket-like pattern. The result is a cloth with a slightly textured surface and an even, tight structure. The same weave is used for bags, outdoor covers and tents, which is why the fabric of a shade sail can feel familiar if you've handled a camping bag.
The yarn
The yarn is polyester, a synthetic fibre that's widely used outdoors. Polyester holds its shape well when it's pulled tight, which matters for a sail: a shade sail only looks and works right when it's tensioned firmly from every corner.
What it means for you
- A smooth, solid look. A woven, coated fabric looks like a single sheet of colour from below, rather than a mesh.
- Clean edges and colours. Our sails come in cream, white, black and charcoal, depending on the shape.
- A fabric that needs tension. Like all sails, an Oxford sail should be pulled flat, without wrinkles or pockets. A loose sail flaps and collects water; a tight one doesn't.
What the PU coating does
PU stands for polyurethane. On a shade sail, it's a thin coating applied to one side of the woven polyester.
The coating fills the tiny gaps between the threads, which gives the fabric its tight, solid look. Installed with a clear slope, rain runs towards the low corner instead of sitting on the sail.
It's worth being clear about what a coated shade sail is, and what it isn't:
- A shade sail is designed for shade. Installed with a slope, water should run off the low corner, not sit on the sail.
- A shade sail is not a roof. In heavy or prolonged rain, water can find its way through, especially at seams and corners.
- The manufacturer recommends treating the fabric with a waterproofing spray if you expect heavy rain. Treat that as a care step, not as a guarantee.
The single most important rule for any coated sail is simple: never let water pool on the fabric. Pooled water is heavy, it stretches the fabric and it puts a lot of load on the fixing points. A good slope and firm tension prevent it.
Oxford vs knitted shade cloth: how they compare
Here's a fair, side-by-side look at the two families. Specifications vary from product to product, so always check the listing of the exact sail you're looking at.
| Woven Oxford with PU coating | Knitted shade cloth | |
|---|---|---|
| Structure | Tight woven polyester, coated on one side | Open knitted mesh |
| Light rain | Coated, solid-looking fabric; install with a slope so water runs off | Rain generally passes through the mesh |
| Airflow | Air moves less freely through the fabric | Air passes through the gaps in the knit |
| Look from below | Solid, even colour | Visible mesh texture |
| Main installation point | Slope is essential so water runs off | Slope still helps tension and appearance |
What does this mean in practice? If you want a solid-looking sail over the barbecue or the outdoor table, a coated Oxford sail is a sensible choice, as long as you give it a slope. If your priority is airflow in a very still, enclosed courtyard, keep in mind that air moves less freely through a coated fabric, so give the sail plenty of height above head level and leave the sides open.
Shape also plays a part. A rectangle shade sail in cream covers more ground for its size, while a charcoal triangle shade sail suits smaller or odd-shaped spaces. Whatever the shape, the size you order should be smaller than the space between your fixing points: our step-by-step article on how to measure your space for a shade sail shows you how to work it out.
Caring for coated shade sail fabric
A little care goes a long way with a coated fabric. These are the habits that matter most.
Installation habits
- Slope it. As a general rule of thumb, allow a slope of around 20% (about 20 cm of drop per metre). On a rectangle sail, put two diagonally opposite corners high and the other two low. On a triangle, fix one corner lower than the other two.
- Tension it. Tighten the turnbuckles a little at a time until the fabric sits flat. It's normal to re-tension after a few weeks as the fabric settles.
- Fix it to solid structure. Rain and wind both pull on the corners. Use masonry walls, structural beams or posts set in concrete. Our article on shade sail posts explains materials, footings and heights.
Everyday care
- Take it down in bad weather. Remove the sail before storms and strong winds, and over winter if you're not using it.
- Clean it gently. Use a soft brush and mild soapy water, then rinse with clean water. Avoid harsh chemicals and pressure washers, which can damage the coating.
- Dry before storing. Let the sail dry completely before you fold it away, so it doesn't stay damp in storage.
- Keep heat away. Keep the fabric well clear of barbecues, fire pits, patio heaters and anything with a flame.
Our installation guide covers fixing points, slope and tension step by step, with a downloadable PDF for each sail shape. If you're unsure whether a wall, beam or post is strong enough, ask a qualified tradesperson, and check with your local council whether your sail needs approval.
Conclusion
Shade sail fabric isn't just a line in the specifications. Our sails use a woven Oxford polyester with a PU coating: a tight, solid-looking fabric. It isn't a roof, it needs firm tension, and it should never be left holding water. Choose your shape and size, plan a proper slope, fix it to solid structure and take it down in bad weather, and your sail will do what you bought it for: make the backyard a more comfortable place to be. Browse the shapes and colours in our shade sail range, and if you'd like a second opinion on size, send us your measurements for a free Size Check.
FAQ
What fabric are your shade sails made of?
All our shade sails are made of 100% polyester Oxford fabric with a PU (polyurethane) coating.
Will a shade sail keep all the rain out?
No. A shade sail is designed for shade, not as a roof. Install it with a clear slope so water runs off. In heavy rain, water can come through, especially at seams and corners. Never let water pool on the fabric.
What is the difference between Oxford fabric and shade cloth?
Oxford is a tight woven fabric; on our sails it's coated on one side. Knitted shade cloth is an open mesh that lets air and rain pass through. The woven, coated fabric looks more solid from below.
How do I clean a PU-coated shade sail?
Use a soft brush with mild soapy water, rinse with clean water and let the sail dry completely before storing it. Avoid harsh chemicals and pressure washers.
Do I need to treat the fabric?
The manufacturer recommends treating the fabric with a waterproofing spray if you expect heavy rain. It's a care step: you still need a good slope, firm tension and to take the sail down in storms.