Edge Detailing: The Difference Between Seamed and Polished Glass
When you order a glass veranda, the quality of the glass isn't just about its strength—it's also about the finish of its edges. Because the edges of the glass are often exposed or visible through the frame, how they are treated at the factory matters. There are two primary types of edge finish: seamed (or arrissed) and polished. Each has its own role to play in the safety and final appearance of your roof.
Safety first: isolate power before touching a motorised system, and never work at height off a ladder alone. If in doubt, book a fitter rather than forcing a mechanism.
What is a Seamed Edge?
A seamed edge is the basic treatment for toughened glass. After the glass is cut, a sanding belt is used to take the sharp corners off the edges. This makes the glass safe to handle and removes small 'micro-cracks' that could cause the glass to shatter during the toughening process. The edge remains slightly frosted and 'raw' in appearance.
The Premium Finish: Polished Edges
Polished edges go several steps further. The glass is run through a multi-stage machine that grinds the edge to a perfectly smooth, flat profile and then buffs it to a crystal-clear shine. This is the gold standard for glass rooms where the edge of the glass might be visible at the front of the structure or in sliding door systems.
- Seamed Edge: Standard for edges hidden within the frame.
- Polished Edge: Best for exposed glass corners and glass-to-glass joints.
- Safety: Both treatments ensure the glass is safe to handle.
- Structural Integrity: Smooth edges reduce the risk of stress fractures.
When Does the Edge Finish Matter?
In most standard verandas, the rafters cover the long edges of the glass, so a seamed edge is perfectly acceptable. However, at the front of the roof, the glass often overhangs the gutter slightly. A polished edge here looks significantly better, catching the light and providing a premium, high-end feel to the whole structure.
Ensure your quote specifies if the exposed edges will be polished or just seamed.
Questions we get asked on repair calls
Is polished glass more expensive?
Yes, because it requires an extra manufacturing step on a specialized machine, but the aesthetic improvement for exposed edges is significant.
Can you polish the edges after the glass is installed?
No. Glass must be edged and polished before it goes through the toughening furnace. You cannot grind or polish toughened glass on-site.
What is an 'arrissed' edge?
Arrissed is another word for seamed—it simply means the sharp 90-degree corner of the glass has been sanded down at a 45-degree angle.
Does all veranda glass come with polished edges?
Not by default. Many budget systems only provide seamed edges. High-end systems like Weinor often feature polished edges on all visible glass boundaries.
Impact on Glass Strength
While both seaming and polishing make the glass safe for the toughening oven, a polished edge is technically the 'healthier' edge for the glass. By removing all surface imperfections and pits, a polished edge is less likely to suffer from spontaneous breakage due to thermal stress or edge impact.
In short
Why the choice between seamed and polished glass edges is about more than just aesthetics—it's about safety, durability, and the final look of your veranda.
Get it looked at
Experience the difference of premium finishes—view our glass samples at a site visit.
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