Frequently Asked Questions

If you're not part of the glass business, even peripherally, it can seem a bit mysterious. We have lots of different industry-specific terms, obscure methods and some very specialized tools and techniques.

Most importantly, we have lots of knowledge and experience. Here you'll find a small collection of information you might need to know, but are unlikely to find elsewhere (at least in an understandable format).

And of course, if you need advice and can't find the answer here, feel free to give us a call or come in for a visit. Can't hurt to check back here every now and again. This section is bound to grow over time.

Please forgive me for not offering you a hot beverage. Or more accurately, for not offering an opportunity to partake of our font of knowledge. If you have any questions about glass in general and can't find the answer here, please feel free to send an email to webmaster@cosmosglass.ca and I shall do my utmost to answer in a timely manner.


  • General Q&A

    • What's the difference between an Arriss, a Polish and a Bevel?

      • We have a number of different options for glass edge treatment, from simple to elegant. The primary differences are cost and aesthetics. Pretty edges cost more.

      • Raw edges are also available at no additional cost, but we do not provide bandages.

      • In general our insulated glass units are protected with masking tape and do not require any special edging. If you specify no-tape at the time of order, we generally apply a light hand arriss.

      • Arriss

          A sanded edge, whether it be done by hand or with a machine. Simple, effective, but not very decorative.

          This edge can be applied to any shape of glass, including the inner edges of cutouts and notches.

      • Polish

          An edge which has been passed over grinding and polishing wheels to give it a nicely rounded profile.

          Most commonly used for shelves and tabletops, this edge can be applied to almost any shape of glass.

      • Bevel

          A specialty edge which slopes gradually from full glass thickness to a fine, thin edge. Available in various widths from 0.5" to 1.5", it is quite popular for high-end mirrors.

          This type of edge requires specialty equipment and must be ordered. Common delivery times are on the order of 2-3 weeks.


    • What are your tolerances for cutting and polishing?

      • The standard industry-wide tolerance for cut glass is ±1/16". Complex hand cuts and intricate polishes may be subject to greater tolerances, particularly when tight inside corners or rectangular cutouts are involved.

      • We do not guarantee the fit of glass cut to match templates or measurements provided by the customer.

    • How do I read a tape measure?

      • I tried to fit this into a single FAQ section, but it proved to be far more involved than I had once thought. So I built a new section.

      • Click here for the tutorial.


  • Sealed Units Q&A

    • What is Low-E Glass?

      • Low-E is the short name for Low Emissivity. In a nutshell, it means the glass has a metallic or ceramic coating on it which helps reflect IR energy (i.e. heat). When placed in a sealed unit, it can either reflect IR back in to the house in winter, or back outside in summer.

    • What is Argon gas?

      • Common sealed units contain air. That's it, just air. It's very dry air, because it's sealed at the factory, but its plain old air nonetheless. It acts as an insulation barrier to keep heat from crossing through the unit.

      • Argon gas is an upgrade. It's much more dense, and as such has a higher insulation value which increases the overall effectiveness of the unit.

    • Why do sealed units fail?

      • Insulated glass units are sealed at the factory at room temperature. Because they are sealed, this means that as they get colder the pressure inside will drop, and as they heat up the pressure will rise.

      • This effect is known as heat cycling. So, every night your windows contract, and every day they expand again. Because of this constant movement, the seal between the spacer and the glass becomes fatigued and eventually fails.

      • Certain factors can speed up the process. Windows on the east side of your home tend to expand more rapidly (warm sun on cold glass in the morning). Those on the south side face more sun overall and expand to a greater degree (no pun intended). Windows on the north face of homes or in constant shade are quite commonly the last to fail.

      • Many other factors can contribute to the failure of a sealed unit. A shifting house, blinds which are too close to the glass or an awning which perpetually shades only the top portion of a window can decrease the life of a unit, or even cause an outright failure.

    • If only one pane of glass is broken, can you re-use the good one?

      • For standard sealed units, it's more cost effective to use new glass to fabricate an entirely new panel. The labor required to dismantle, clean and reassemble a panel using some of the old glass is significantly more expensive than the cost of new glass.

      • However, if for any reason a customer wishes to re-use the old glass, we can oblige. We have rebuilt sealed units containing stained glass, carved or etched designs, obsolete patterns, and a few with antique glass.

    • Can you wash the rest of my windows?

      • Yes we can.

      • Right after we replace them.

  • Frameless Showers Q&A

    • Do frameless showers leak?

      • Short answer: Yes

      • Frameless showers are built to look great and function well. They are not, however, fish tanks with doors. In any situation where you have 6 shower heads pointing at the door, you will get leakage. If you have a wet door swinging out into the bathroom, you will get drippage. And if you have a steamer, well, the steam will escape through the gaps.

      • The whole idea of frameless showers is to minimize the hardware and increase the glass surface area. We strive to make gaps as small as possible, often using razor-blades to check clearances. But the honest bottom line is this: without a physical seal, water will escape.

  • Flat Glass and Mirror Q&A

    • What is Laminated Glass?

      • Laminated glass is a type of safety glass which incorporates a plastic layer between two panes of glass.

      • Lami is used in situations where you want the glass to remain in place if it is broken. Automobile windshields are a good example. If your windshield cracks, you don't want wind-driven shards flying into your face. Similar applications include sloped skylights and commercial doors.


    • What is Tempered Glass?

      • Tempered glass is a type of safety glass which has been heat treated for increased strength.

      • Tempered glass is very strong on the face, much more so than regular float glass or laminated glass. In the event that it does break, the entire pane will crumble into tiny pieces. The theory is that tiny pieces falling won't cause nearly as much damage as large shards.

      • Typical applications for tempered glass include tabletops, fridge shelves, patio doors, shower panels and railing glass


    • Can you remove scratches?

      • Once upon a time, yes. Minor scratches (ie: those you can't feel with a fingernail) could be buffed out using special polishing compounds and buffers. Alas that particular service has been whittled from our repertoire because of the considerable amount of time required.

      • In short, it's possible, but too darned expensive.


    • Can antique mirrors be re-silvered?

      • Actually, yes.

      • Unlike to the average piece of float glass (no matter how old), antique mirrors often have a much higher intrinsic value. Some have etchings or carvings, many have sentimental value. There are many considerations which might warrant the expense of re-silvering.

      • Show us the mirror, we'll get you a price.