Nobody touched it. Nothing fell on it. It was just sitting there under a cover in the garden all winter, and somehow it's cracked. Or shattered. Or split clean in half.
If you've just discovered this, don't worry. You haven't done anything stupid. This is genuinely one of the most common things we deal with, especially between February and May. We cut replacement rattan table glass almost every day during that period, and the story is always the same. "It just broke on its own."
It did, kind of. But there's a reason, and once you understand it, you'll know exactly how to stop it happening again.
The Quick Version
The glass your rattan set came with was cheap. Thin. Untoughened. It can't handle being left outside through a proper cold winter. Repeated freezing and thawing eventually cracks it. Toughened glass handles the same conditions with no issues whatsoever.
That's the short answer. If you want to know the why behind the why, keep reading.
Two Types of Glass, Massive Difference
There's annealed glass and there's toughened glass. Your rattan set almost certainly came with annealed.
Annealed is basic. It comes straight off the production line without any treatment. Cheap to make, easy to cut, and perfectly fine for, say, a picture frame or a cabinet door. But it's weak against temperature changes. Really weak. And that's the problem.
Toughened glass, also called tempered, has been through a furnace at about 620 degrees and then blasted with cold air to cool it down fast. That process does something interesting to the internal structure. It creates a kind of built-in compression that makes the glass roughly five times stronger. More importantly for this conversation, it makes the glass far more tolerant of temperature swings.
Most rattan furniture ships with 5mm annealed glass. Some of the cheaper sets use 4mm. Neither was built to spend five months outside in weather that freezes and thaws repeatedly.
What Freeze-Thaw Actually Does
All glass expands a tiny bit when it warms up and contracts when it cools down. Toughened, annealed, doesn't matter. The physics is the same. What's different is how well the glass handles the stress that comes with it.
Picture a cold night. Temperature drops below zero. Your table glass contracts. Then the sun comes up in the morning and warms the top surface while the underside, sitting against the cold rattan frame, stays cold. Now you've got one face of the glass trying to expand while the other one is still contracted. That's internal tension.
One night of that? Fine. The glass can take it. Ten nights? Probably still okay. But three solid months of it happening over and over, the stress builds up. Micro-cracks start forming from tiny flaws in the surface or chips along the edge that were there all along. And then one morning, one particular frost, it goes. The crack was basically loaded and waiting. The final freeze was just the trigger.
Toughened glass goes through all the same expansion and contraction, but that internal compression from the tempering process fights back against the stress. The glass flexes, absorbs it, and carries on. Year after year, no issue.
Water Makes Everything Worse
Here's the bit most people don't think about. Rattan tables have a recess, a little channel or lip that the glass sits in. Water gets into that channel. Rain, condensation, dew, whatever. It pools up against the edges of the glass and along the bottom of the recess.
When that water freezes, it expands. About 9% in volume. Doesn't sound like much, but it's enough to push outward against the glass from the frame side. On its own it probably wouldn't crack the glass. But combined with thermal stress that's already been weakening the glass for weeks? It's often the thing that tips it over the edge.
This is why a lot of people find the glass cracked after one particularly harsh frost rather than gradually over time. The glass was already compromised. The ice just finished the job.
Little Chips, Big Problems
Annealed glass doesn't forgive edge damage. That tiny nick on the corner from when you knocked it taking it out for a barbecue back in August? The bit of grit that got trapped between the glass and the frame? Those are stress concentration points. Thermal stress radiates out from exactly those kinds of flaws.
A chip that was completely invisible all summer becomes the starting point for a crack in January. You won't see it coming. It'll just appear one morning, running from that spot you'd forgotten about.
Toughened glass isn't immune to edge chips, but the built-in compression makes it far less likely that a small flaw will turn into a full-on crack under temperature stress.
Why Don't They Just Put Better Glass in These Sets?
Money. Simple as that.
A 5mm annealed glass top for a rattan dining table costs a fraction of a 6mm toughened one. When you're manufacturing thousands of garden furniture sets at a competitive price point, every pound on the bill of materials gets multiplied across the whole production run. Cheap glass keeps the sticker price down in the garden centre.
Nobody tests this furniture outside in December, either. It's designed, photographed, and sold for sunny afternoons on the patio. The glass works fine in those conditions. It just wasn't designed to survive a proper British winter, and there's no regulation saying it has to be.
Indoor furniture glass falls under BS EN 12150 safety standards. Outdoor garden furniture sits in a grey area where manufacturers can and do use the cheapest glass they can get away with.
How to Make Sure It Doesn't Happen Again
If you're replacing the broken glass anyway, you might as well solve the problem at the same time.
Go toughened. This is the big one. Toughened glass handles British winters without breaking a sweat. It costs a bit more than annealed but you're buying once instead of every couple of years. A 6mm toughened replacement for a standard rattan dining table isn't expensive and it's dramatically stronger than what you had.
Step up the thickness while you're at it. If the original was 5mm, go to 6mm. Barely any weight difference, noticeably more rigid, and thicker glass absorbs temperature changes better because there's more mass to distribute the stress through.
Cover the table from about October. Waterproof cover. Keeps rain off the glass, stops water pooling in the recess, which means no ice forming against the edges. A cover costs next to nothing and protects the whole set, not just the glass.
Better yet, take the glass inside. October, lift it out. Store it flat in the garage or the shed. March, put it back. Thirty seconds each way, completely eliminates winter exposure. Job done.
Clear the muck out of the frame recess before you put the glass back in spring. Leaves, grit, dead spiders, whatever's been building up in there over winter. That debris creates pressure points against the glass edges. Two minutes with a cloth and you've removed the risk.
→ Order a toughened replacement: Replacement Glass for Rattan Garden Tables
So What Now?
Glass is broken. It happens. The fix is a replacement piece cut to your table's measurements. You'll need the shape, the dimensions, and the corner radius. We do this constantly, especially in spring.
Measure your frame, pick your glass (clear is standard, grey and bronze look cracking on darker rattan), and order. Most pieces go out within five to seven working days.
→ How to get the measurements right: How to Measure a Rattan Table for Replacement Glass
→ Order now: Glass Table Tops Collection
