Quick answer: When frame glass breaks, leave the frame face up, tape across the broken glass to hold the pieces still, and carry it upright rather than flat. Never lay it face down. Most of the time only the glazing is damaged, and a framer can fit new glass without touching the art.
Glazing is the framing word for whatever sits in front of the art, glass or acrylic. It is the consumable layer, meant to fail when a frame comes off a wall. The damage that costs you happens in the next ten minutes, when a loose shard slides across a print. Supreme Pictures handles frame repairs at 7025 Tomken Rd Unit 4, near the Tomken and Derry Road intersection in northeast Mississauga.
What should you do in the first ten minutes after frame glass breaks?
Work in this order. Every step moves glass away from the art, not across it.
- Look before you touch. Note which way the frame is facing. If it landed face down on carpet, leave it.
- Shoes and proper gloves. Framing glass breaks into long hooked slivers, not small cubes. Leather or cut resistant gloves.
- Tape the broken face. Painter’s tape across the glass in a grid, then a second pass at right angles, so cracked sections cannot slide.
- Keep the glass side up. Taped and facing the ceiling, gravity holds the loose pieces against the tape instead of onto the art.
- Do not lift the frame flat. Held horizontally, a large frame flexes in the middle, and flexing turns one crack into twenty. Lift it vertically.
- Do not tip it over to check the back. That single movement rakes shards across the artwork.
- Vacuum the floor twice. Once with the head, once with the crevice tool along the baseboards.
- Do not open the frame yourself. Removing the backing releases whatever is loose inside onto the art.
Transport is the last risk. Lay the taped frame glass side up on a folded blanket, flat and fully supported, never on edge between the seats. If the piece is a mirror, the same steps apply, and the rebuild path runs through our custom mirrors service.
Is the artwork damaged, or only the glazing?
Flat, taped and glass side up, a frame can be assessed without opening it. Hold a phone light low to one side and look through the glass at a shallow angle. Raking light reveals damage that overhead light hides.
- Nothing at all. The usual outcome. The crack stops at the glass and the mat window keeps the art below the break line.
- Dents on the mat bevel. The mat took the hit. Re-cutting a mat is routine work.
- A scratch in the paper. A bright line under raking light. Let a framer look before anything moves.
- Artwork stuck to the glass. Prints framed without a mat bond to glazing over years of humidity cycling. Do not pull, pry or peel.
- Glass dust on the surface. Fine white powder along the crack line. It comes off on a bench, not with a sleeve.
The Canadian Conservation Institute names the cause. Its glazing note states that a framed work of art should not touch the glazing. Nearly every broken frame we open with real artwork damage had no mat and no spacer.
Picture frame glass thickness and the rabbet that has to hold it
CCI Notes 11/3 settles the range in one sentence: picture framing glass is usually 2.0 mm or 2.5 mm thick, and 2.5 mm may be preferable because it is more resilient, less likely to chip, and easier to handle safely. Half a millimetre sounds trivial. In a reglaze it is not. A frame built for 2.0 mm may refuse to close on 2.5 mm.
What has to fit inside a 2 cm rabbet
The rabbet is the lip cut into the back of the moulding. Its depth was fixed when the moulding was milled. CCI Notes 11/9 gives the working figure: the frame needs a rabbet deep enough for a mat, a backing board and glazing, about 2 cm in total.
| Layer, front to back | Typical thickness |
|---|---|
| Glazing | 2.0 mm or 2.5 mm glass, 3.0 mm and up for acrylic |
| Window mat | About 1.5 mm per 4 ply sheet, so 3 mm for a double mat |
| Artwork and mount board | 1 mm to 3 mm |
| Backing board | 2 mm to 4 mm |
| Tape seal and hardware | 1 mm to 2 mm |
That package adds up to between 9 mm and 14 mm. The 2 cm figure is the margin that lets a framer swap 2.0 mm glass for 2.5 mm, or add a spacer, without the backing standing proud. When the rabbet cannot take the glazing a piece needs, the frame gets rebuilt.
Which replacement glazing should you choose?
We stock three glazing types: regular glass, non-glare glass, and glass with a 99% UV coating.
| Glazing | Thickness | UV performance | Suits | Trade off |
|---|---|---|---|---|
| Regular clear glass | 2.0 mm or 2.5 mm | Cuts only UV below 300 nm | Posters, open edition prints | No protection where colour fades |
| Non-glare glass | 2.5 mm | Etched surface scatters reflections, filtering is separate | A piece opposite a window | Softens as the gap grows |
| UV filtering glass | 2.5 mm | Blocks up to 99% of UV from 300 to 380 nm | Photographs, watercolours, certificates | Costs more per square foot |
| Acrylic | 3.0 mm minimum on large sheets | UV filtering grades available | Oversized frames, stairwells | Holds a static charge, scratches easily |
CCI treats UV as a threshold, not a preference. Where UV levels run higher than 75 microwatts per lumen and the lights carry no filters, it recommends glazing with a UV filter. Clear glass transmits over 90% of visible light but cuts only the UV below 300 nm. UV absorbing filters take out the band from roughly 300 to 400 nm, where fading happens. Tru Vue rates its Conservation Clear glass at up to 99% of 300 nm to 380 nm UV rays, with light transmission above 89%.
When acrylic beats glass
Acrylic answers two questions: how big, and how much traffic. CCI calls plastic ideal glazing for large works, lightweight and far less likely to break, with one hard rule: large sheets must be 3 mm thick to avoid bowing. One rule runs the other way. Plastic glazing holds an electrostatic charge that lifts pastel, charcoal and any flaking pigment off the paper. Acrylic goes over a large canvas print in a stairwell. Never over a charcoal drawing.
Should the frame be repaired or rebuilt?
Repair means new glazing in the moulding you own. Rebuild means new moulding. The call takes about ninety seconds on the bench.
| Check | Reglaze | Rebuild |
|---|---|---|
| Mitred corners | Tight under thumb pressure | A mitre has opened, or the corner moves |
| Moulding | Finish intact | Split along the rabbet, or the finish has crazed |
| Rabbet depth | Deep enough for the glazing you want | Too shallow for what the art needs |
| Size | Any, including inherited frames | An odd size no stock frame matches |
| Mat | Clean, or cheap to re-cut | Damaged beyond a re-cut |
One case overrides the table. If the backing is corrugated cardboard or plain wood, the package gets rebuilt whatever the glass is doing. CCI Notes 11/9 lists Masonite, corrugated cardboard and wood as not recommended, and calls for acid free 100% rag matboard instead. It costs little to swap once a frame is open.
Beyond saving? The piece moves to custom picture framing for a new moulding, or to our ready made picture and photo frames when the size is standard. Our picture framing in Mississauga guide covers pricing.
What happens when you bring a broken frame into our workshop
Bring the whole thing, taped, glass side up. Here is the bench sequence.
- Intake and shard removal. The frame goes flat, glass up, onto a covered bench. The taped sheet lifts out in one piece where possible, then the frame is vacuumed.
- Inspection under raking light. We check the artwork surface, the mat bevel and the mount, and show you anything we find.
- Measurement. Rabbet depth, sight size and glass thickness, which tells us whether the frame takes 2.5 mm glass, a spacer, or both.
- Frame condition check. Corners, joints, finish and hanging hardware. A reglaze can turn into a rebuild recommendation here, and you hear it before we start.
- Rebuild and collection. New glazing cut and cleaned, mat re-cut if damaged, spacers where there is no mat, backing renewed if it was cardboard, then sealed and refitted. You get the ready date at intake.
Reglaze or rebuild? Send photos of the taped frame and the back through our quote request and we can usually tell you before you drive over.
Get broken picture frame glass replaced in Mississauga
We reglaze frames brought in from across Mississauga, Malton, Brampton and the west end of the Greater Toronto Area. Bring it in one piece, taped, glass side up, and let us open it on a bench. Full details sit on our frame repair service page.
Supreme Pictures
7025 Tomken Rd Unit 4, Mississauga, ON L5S 1R6
Phone: (905) 956-7400
Hours: Monday to Friday 10:30 AM to 7:00 PM; Saturday 10:30 AM to 5:00 PM; Sunday closed
Frequently asked questions
Can I replace picture frame glass myself?
You can, but the risk sits with the artwork rather than the glass. Removing the backing releases loose shards onto the surface, and a cut edge chips the mat bevel on the way in. A framer opens the package on a covered bench, vacuums first, and cuts the new sheet to the rabbet.
How thick is picture framing glass?
Picture framing glass is usually 2.0 mm or 2.5 mm thick. The Canadian Conservation Institute notes that 2.5 mm may be preferable because it is more resilient, less likely to chip, and easier to handle safely. Acrylic glazing runs thicker, and large plastic sheets need 3 mm to avoid bowing.
Does non-glare glass block UV light?
Not by itself. Non-glare glass has an etched surface that scatters reflections, which is a separate property from filtering. UV protection comes from a coating, and UV filtering glass blocks up to 99% of UV in the 300 to 380 nanometre range. Ask for both if the wall gets daylight.
My photograph is stuck to the broken glass. What should I do?
Stop, and bring it in exactly as it is. Prints framed without a mat can bond to glazing over years of humidity change, and pulling separates the emulsion from the paper. Leave the taped glass in place, keep it face up, and let a framer assess the bond on a bench.
Is it worth replacing the glass, or should I buy a new frame?
Reglaze when the mitred corners are tight, the finish is intact, and the rabbet is deep enough for the glazing you want. Rebuild when a corner moves under thumb pressure, the moulding has split along the rabbet, or the backing turns out to be corrugated cardboard.
