# Mirror



## Pauley (Jan 21, 2012)

Made a carousel mirror/book shelf for my grand-daughter. Got it just about finished yesterday. This morning I went into the shop to see a hair line crack in the mirror. Obviously, sometime during the night, it cracked. I don't know how. Is there any way I can prevent this hair line crack from spreading? the crack is so think, you can't even feel it dragging your thumbnail over it....

If I have to replace the mirror, it will mean re-making a lot of the frame work.....

Author: The Other Casualty Of War


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## Pauley (Jan 21, 2012)

Here is a photo of the hairline crack...

Author: The Other Casualty Of War


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## cabinetman (Jul 5, 2007)

There's no way to stop the crack. It may just stay like that, maybe not. If it were mine...I would change it out.










 







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## Tricktech (Feb 2, 2012)

I'm with CM, change it out. There's now way to effect a repair that won't jump out at you screaming "Hey, there's a crack here"

My only real comment on this issue is that problems with glass are rarely a result of anything but the way they are mounted. It doesn't take much, but I'll wager you find the reference surface the top edge of the mirror is mounted to is not straight or has something fouling the mount. Don't just mount another mirror without fully investigating the mount itself.


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## Pauley (Jan 21, 2012)

Thanks guys. I am going to replace the mirror...

Author: The Other Casualty Of War


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## cabinetman (Jul 5, 2007)

Before installing the next mirror, take some 120x wet-or-dry silicon carbide sandpaper and ease the sharp edges of both the glass side and the silvering side. Mirror or glass will crack at a small fissure in the edge, even a nick can do it.

Lay the mirror face down on newspapers on a flat surface, so the newspapers protrude from the edges all around. Spray the edges and back (about1"-2") in on the silvering with a clear acrylic spray (not lacquer). Once mirror is cut, the silvering gets cut, and can oxidize back from the edge. That's why you see old mirror with silvering missing, or it turns black. Spraying the edges prevents that from happening (or at least minimizes the possibility).










 







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## cabinetman (Jul 5, 2007)

Another procedure would be to treat the backside of the frame around the mirror (like the rabbet if there is one), by staining or finishing like the frame. The mirror edge will reflect what it is resting on.










 







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## Pauley (Jan 21, 2012)

cabinetman said:


> Before installing the next mirror, take some 120x wet-or-dry silicon carbide sandpaper and ease the sharp edges of both the glass side and the silvering side. Mirror or glass will crack at a small fissure in the edge, even a nick can do it.
> 
> Lay the mirror face down on newspapers on a flat surface, so the newspapers protrude from the edges all around. Spray the edges and back (about1"-2") in on the silvering with a clear acrylic spray (not lacquer). Once mirror is cut, the silvering gets cut, and can oxidize back from the edge. That's why you see old mirror with silvering missing, or it turns black. Spraying the edges prevents that from happening (or at least minimizes the possibility).
> 
> ...


Actually I never have luck when attempting to cut glass (mirrors). I had my local glass company cut it for me and I installed it. I contacted them after I noticed the crack, and they said I should bring the entire cabinet in and they will replace the mirror and install it in the cabinet for half the cost I already paid. Very nice folks and a nice way to treat customers....

Author: The Other Casualty Of War


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## cabinetman (Jul 5, 2007)

Pauley said:


> Actually I never have luck when attempting to cut glass (mirrors). I had my local glass company cut it for me and I installed it. I contacted them after I noticed the crack, and they said I should bring the entire cabinet in and they will replace the mirror and install it in the cabinet for half the cost I already paid. Very nice folks and a nice way to treat customers....
> 
> Author: The Other Casualty Of War


Too bad you had that problem and had to pay again. If you order the next time ask to have the edges "seamed", and before you install it coat the edges as I suggested, if the glass company didn't do it.










 







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## Pauley (Jan 21, 2012)

cabinetman said:


> Too bad you had that problem and had to pay again. If you order the next time ask to have the edges "seamed", and before you install it coat the edges as I suggested, if the glass company didn't do it.
> 
> 
> 
> ...


I will do that... Thanks!

Author: The Other Casualty Of War


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## Cliff (Feb 5, 2012)

How did you mount the mirror? 
Is it free floating? 
If so the crack is a manufacturing defect.


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## sawdustfactory (Jan 30, 2011)

COuld the frame have contracted after the mirror was installed causing the crack?


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## Pauley (Jan 21, 2012)

Cliff said:


> How did you mount the mirror?
> Is it free floating?
> If so the crack is a manufacturing defect.


I used a extremely thin piece of double sided tape to hold it in place while I put the frame on...

Author: The Other Casualty Of War


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## Pauley (Jan 21, 2012)

sawdustfactory said:


> COuld the frame have contracted after the mirror was installed causing the crack?


Possibly, but I believe I left about a quarter inch all around the mirror because of expanding or contracting....

Author: The Other Casualty Of War


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## cabinetman (Jul 5, 2007)

Pauley said:


> Possibly, but I believe I left about a quarter inch all around the mirror because of expanding or contracting....
> 
> Author: The Other Casualty Of War


I've found the best way to mount glass/mirror is in a rabbet. It can be held in with retainers, a small moulding, or if need be a small bead of clear silicone caulk.

If installed like a raised panel (in a groove), makes it a PITA to remove/replace.










 







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## Pauley (Jan 21, 2012)

cabinetman said:


> I've found the best way to mount glass/mirror is in a rabbet. It can be held in with retainers, a small moulding, or if need be a small bead of clear silicone caulk.
> 
> If installed like a raised panel (in a groove), makes it a PITA to remove/replace.
> 
> ...


I'll keep that in mind the next time, for sure.....

Author: The Other Casualty Of War


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## Cliff (Feb 5, 2012)

Pauley said:


> Possibly, but I believe I left about a quarter inch all around the mirror because of expanding or contracting....


You covered the mirror all but a little strip around the edge? 

I suspect this is why it cracked. 

Using an adhesive to connect a piece of glass to a piece of wood almost guarantees a conflict when the wood starts moving and the glass doesn't. Something has to give. 

I suppose a few dabs of silicone along an edge might be fine but only because silicone is so flexible it'll serve to let the glass float independently of the wood. But silicone might wreck the mirroring if it got on it. 
Best to let glass float freely in a groove.
Raised panels in door frames should also float freely. 

There is a product called SPACE BALLS that some folks use to sort of prevent the panels or glass from rattling around. I've never used 'em, but lots of people like 'em.


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## cabinetman (Jul 5, 2007)

Cliff said:


> Best to let glass float freely in a groove.
> Raised panels in door frames should also float freely.
> 
> There is a product called SPACE BALLS that some folks use to sort of prevent the panels or glass from rattling around. I've never used 'em, but lots of people like 'em.


Mounting glass or mirror in a groove is not recommended. Doing that would require the installation before glue up of the frame, and before finishing. With the glass being captive, the door would have to be dismantled to repair or replace the glass/mirror. In most cases that would destroy the joints.

Mounting in a rabbet (or even flush to the back of the frame if necessary) would be the best method, IMO.










 







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## 2lim (Aug 30, 2009)

I work for a glass shop here in London, and we always install either into a rabbet, with simple trim(stops) or we install to a rabbet, and cover the back with cardboard, or we install to a rabbet and use a thin bead of silicone. If you do not seal the silicone in, then it typically will not tarnish the mirror. The other trick is to use an acrylic interior caulking, as it will nto tarnish mirror. We never ever do a totally free float in a groove, as we have to cut the frame apart after if we ever have to service it.

Pretty much, cabinetman hit the nail on the head.

Simon


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