If you’ve spent time looking at the cut edge of an ordinary piece of glass, you’ve seen it: a faint green stripe running along the edge that gets stronger as the glass gets thicker. That’s iron — specifically iron oxide — embedded in the raw material the glass was made from. It’s not a flaw. It’s just what soda-lime float glass looks like.
For most installations the green tint doesn’t matter. For a $50,000 ensuite renovation with book-matched marble walls, brass plumbing, and a frameless shower enclosure that takes up half the room, it matters a lot.
Starphire is one answer. Below: what it actually is, when it’s worth the upgrade, when it isn’t, and what to expect to pay.
Why standard glass has a green tint
Standard architectural glass — the kind in windows, shower doors, and mirrors — is made by floating molten glass on a bath of liquid tin (the “float glass” process invented by Pilkington in the 1950s). The raw silica sand used in the process contains trace iron, typically around 0.10–0.12% by weight as iron oxide (Fe2O3). That’s a tiny amount, but iron is a strong colorant. It absorbs red and blue wavelengths preferentially and transmits green — so the more glass light has to pass through, the greener the perceived colour.
You see this most obviously in two places:
- The edge. When you look at a piece of glass on edge, light is travelling through several inches of material instead of the 1/4″ or 1/2″ face thickness. That’s why the green tint shows there first.
- Thicker panels. A 3/8″ or 1/2″ frameless shower enclosure has noticeably more green than the 1/4″ picture window in the same house. Mirrors are especially affected because light traverses the glass twice — once entering, once reflecting back.
How Starphire is different
Starphire is a brand of low-iron glass — currently manufactured by Vitro Architectural Glass (which acquired the product line from PPG Industries in 2016, but it’s still widely referred to as “PPG Starphire”). The trick is in the raw materials: Starphire is made from silica sand with significantly lower iron content — roughly one-tenth that of standard float glass, around 0.01% Fe2O3.
The result is glass that’s measurably closer to true colourless. Specifically:
- No visible green at the edge. The cut edge looks pale blue-white, not green.
- Higher light transmission. Standard 1/2″ clear glass transmits about 83% of visible light. Starphire 1/2″ transmits around 91%. Thinner glass narrows the gap; thicker glass widens it.
- Truer colour rendering. Whatever you’re looking at through Starphire — marble, paint, skin tones, art — reads with its actual colour temperature instead of being shifted slightly cool/green.
Starphire is not the only low-iron glass on the market. Pilkington’s Optiwhite, Guardian’s UltraClear, and Saint-Gobain’s Diamant are functionally equivalent products from competing manufacturers. Spec’d out, all four perform similarly. Starphire dominates the North American conversation because it’s the brand North American architects and luxury hotels have specified for thirty years — Apple’s retail stores famously use it for storefronts, glass stair risers, and balustrades — but the others are not lesser.
Where the difference is visible
Frameless shower enclosures
The single most visible application. A frameless shower has thick glass (3/8″ or 1/2″), large panel sizes, and many cut edges — door, side panel, fixed return — all of them at eye level. In a bathroom finished with light stone, white tile, or polished nickel hardware, standard tempered glass reads visibly green at every edge. Starphire eliminates that. See our Oakville shower enclosure page for installation specifics.
Custom mirrors
Mirrors compound the green-tint problem because light passes through the glass twice — once entering, once reflecting off the silvered back. A standard bathroom mirror against a marble vanity reads with a slight green cast in the reflection that’s instantly obvious next to a low-iron mirror. This is the application where the upgrade is most often worth it for clients who’ve invested in real stone or designer hardware. More on custom low-iron mirrors.
Steam shower enclosures
Steam enclosures have more glass than a regular shower — door + side panels + transom + sometimes fixed returns — and the volume of glass means the green tint compounds visibly. Steam enclosures are also typically built into the most expensive bathroom in the house, where the rest of the room has been finished to a standard that the green tint will undermine. More on steam enclosure construction.
Glass walls and partitions
In a residential setting — wine cellars, glass walk-in closets, see-through office partitions in a home office — low-iron glass keeps the visual continuity intact. You’re meant to see through the partition; standard glass adds a slight green filter to whatever’s behind it. In a commercial conference room with branded materials or specified paint colours, the same logic applies.
Glass railings — sometimes
Glass railings benefit less than enclosures or mirrors. The glass is usually thick (1/2″ or thicker) so the green tint is real, but you’re looking through the face of the panel, not the edge, and the background (your view, the room) dominates the visual impression. Where Starphire does matter on a railing: short interior staircase runs against light walls, where the glass is at face-on viewing height; or any railing on a feature stair where the glass is the design element. See our railing page.
Glass furniture, shelves, table tops, display cases
Anywhere you’re looking through the edge of a glass piece on a daily basis — a glass coffee table, a glass shelf above a marble vanity, a display case in a retail interior — Starphire reads as designed. Standard glass reads as a daily reminder of compromise.
When standard glass is fine
Honest counter-position, since this page is meant to be useful:
- Utility spaces. Basement bathrooms, secondary showers, rental units. The cost-to-visual-benefit ratio doesn’t justify the upgrade.
- Thin glass. 1/4″ tabletops, picture-frame glass, shelves under 3/8″. The green tint is barely visible and the light-transmission gap closes.
- Dark surroundings. Dark stone, charcoal walls, walnut cabinetry. The dark background absorbs the slight green colour shift; you simply won’t see it.
- Heavily textured glass. If you’re specifying frosted, fluted, rain, or reeded glass, the texture itself disrupts the colour and the iron content matters less.
- Mirrored back surfaces in dim spaces. Powder rooms, hallway mirrors, anywhere the lighting is low and not used for grooming. The green cast is not perceived as readily.
If you’re describing your installation and any of those applies — standard tempered glass is the right answer. Don’t pay for an upgrade you won’t see.
Light transmission and the energy question
One application most homeowners don’t think about: low-iron glass also performs better as a light-transmitting material, which matters for skylights, pool enclosures, and greenhouse applications. The 8-percentage-point gap in visible-light transmission at 1/2″ thickness translates to a noticeably brighter space at the same panel size. For a glass-roofed pool enclosure or a skylit ensuite, this is a structural design consideration, not just an aesthetic one.
Solar performance — heat gain — is essentially the same between standard and low-iron clear glass, because the iron that’s removed is the colorant, not the IR-blocking element. If you need solar control, you specify a low-E coating or a tinted/reflective layer separately, on either base glass.
What Starphire costs
At Lux Glass, the Starphire low-iron upgrade adds exactly 35% to the glass cost. Some examples:
- Custom frameless shower enclosure (door + side panel): a $1,800 standard installation moves to roughly $2,300–$2,400 with Starphire glass.
- Custom vanity mirror, ~30 sq ft, flat polish: a $1,000–$1,200 standard mirror moves to roughly $1,400–$1,600 with low-iron substrate.
- Steam shower enclosure with transom: a $2,500 standard installation moves to roughly $3,200 with Starphire.
The 35% applies to the glass cost specifically, not the entire installed price — hardware, labour, and templating don’t change. As a rough rule, a Starphire upgrade represents 20–30% of the total project price for most custom installations.
How Lux Glass uses Starphire
We stock Starphire and install it specifically for clients who ask for it. Two practical points worth knowing:
- We bring physical samples to every quoting visit. Standard tempered next to Starphire, both at the same thickness, so you can compare them against your own finishes — your marble, your hardware, your paint — instead of in our showroom under different light. The decision is much easier with samples in hand.
- We don’t push the upgrade. If your installation is a basement bathroom or a utility space, we’ll tell you so. Premium upgrades only make sense where you’ll see the difference.
Every Lux Glass installation — Starphire or standard — is backed by our 5-year workmanship warranty in writing.
Frequently asked questions
Is “Starphire” the same thing as “low-iron glass”?
Starphire is a specific brand of low-iron glass, currently made by Vitro Architectural Glass. Other brands of equivalent low-iron glass include Pilkington Optiwhite, Guardian UltraClear, and Saint-Gobain Diamant. The four perform essentially the same; the term “low-iron glass” is the generic category, and “Starphire” is the brand most often specified by name in North America.
How much more does Starphire cost?
At Lux Glass, the upgrade adds exactly 35% to the glass cost. Hardware, labour, and templating don’t change, so the upgrade’s effect on total project price is typically 20–30%.
Can you tell the difference in Starphire glass without comparing samples side-by-side?
Most people can spot the green tint of standard glass once it’s pointed out, especially at the edge of a thicker panel. Whether the difference is meaningful enough to pay for depends on the rest of the installation — light stone surroundings make it obvious; dark or busy backgrounds hide it. Bringing physical samples to your home is the only way to decide reliably.
Is Starphire glass tempered? Is it as strong?
Yes. Starphire glass can be tempered to the same standards as regular glass (CAN/CGSB-12.1 in Canada). Strength, breakage performance, and safety characteristics are identical. The only difference is the iron content of the base material.
Does Starphire work for steam showers?
Yes — and it’s actually the application where the difference is most visible, because steam enclosures contain more glass than a regular shower (door, side panels, transom). Vitro publishes Starphire in the same tempered and laminated specifications used for steam-shower applications.
Should I use Starphire for glass railings?
Sometimes. For a feature staircase against light walls — where the glass itself is part of the visual design — yes. For a deck railing where the view is the focus — usually not, because the eye reads through the panel to the landscape and the slight tint disappears against the variation of the background.
Are there low-iron mirrors?
Yes. The same low-iron substrate (Starphire or equivalent) is silvered to make low-iron mirror. This is where the upgrade is most often worth it for clients who’ve invested in real stone or designer hardware, because mirror compounds the green tint by passing light through the glass twice.
Can I see the green tint in my existing shower glass?
Look at the edge of the door or any cut panel. If you see a green band along the edge, that’s iron-oxide tint in standard float glass — the contrast against the room behind it tells you how visible it is in your specific installation.
The short version
Starphire low-iron glass exists because standard glass has a faint green tint that gets stronger with thickness. In high-end installations finished with light stone, brass, or designer hardware, eliminating that tint is a noticeable upgrade. In utility spaces or against dark backgrounds, the tint is invisible and the upgrade is wasted money. Lux Glass installs Starphire on request, charges exactly 35% more for the glass, and brings physical samples to every quote so you can decide against your actual finishes.
Ready to talk through your project?
Call 416-897-0767 or request a free in-home consultation. We’ll bring Starphire and standard tempered samples, hardware finishes, and recent project photos so you can decide on real surfaces, not in a showroom.
Want a specific application?
- Custom shower enclosures in Oakville — frameless & Starphire-clear
- Steam shower enclosures in Vaughan — sealed-top with transom
- High-end custom mirrors in Mississauga — vanity, gym, and feature-wall
- Frameless glass railings in Burlington — decks, stairs, and balconies