Large Glass Display Doors

Glazing and hardware advice for big glass doors on a reproduction display case. February 6, 2007

I am building some high-end display cases for an antique dealer that are to be reproductions (without the carving) of some antique cases he currently has. The old ones have wood-frame glass doors 42 inches wide by 62 inches high. They sag and rub quite a bit at the bottom. My doors will be even heavier because I don't think I can use non-tempered glass; this has to be at least 3/16 thick because of rippling in large panes of 1/8, whereas the old glass is probably 1/16. Does anybody have experience with such wide hinged glass doors? I am thinking of adhering the glass to the frame with silicone to give extra resistance to racking. I think this is a problem only for the guy who has to replace the glass someday (hopefully not me). Any comments on the silicone or the feasibility of these doors? What would you say is the outside width limit for hinged doors with stiles and rails of say 1-1/4" by 3"?

Also, I need to find hardware to lock these doors, which are one per case and overlay the frame. Most cabinet locks are installed in the edge, for inset application. I don't particularly want to use the "espagnolette" locks, which are surface mounted vertical bolts the full height of the door. Any ideas for a lock?

Forum Responses
(Architectural Woodworking Forum)
From contributor A:
If I understand, the door frame is 1 1/4 inches thick. That is thick. It is a good sized door, but I don't see a need to silicone the glass. I would use glass retainer strip. If the doors are built well, they shouldn't sag, plus silicone looks tacky. If you get sag, it will be in the hardware.

I am still scratching my head. I know of a couple locks, cam style, but they won't work with such a thick frame. Why don't you want to use espagnolette bolt locks? I think that would look classy and add to the antique feeling.

As far as your width question, I think you are there. I have built doors roughly 30" by 60", but I think you may be at the edge of the envelope without going to some extreme construction methods like what you would find in passage doors. In any event, I think the size will be limited to what your hardware can handle. If your glass is more than 18" off the ground, you don't need tempered. Good luck with these. I hope you are making good money on them.

From the original questioner:
The joinery will be haunched mortise-and-tenon, so I feel confident there. The idea of silicone was in addition to the wood strip for retaining the glass, so the silicone won't show. I think it would add rigidity to the door.

I am interested in your comment about tempered glass. The bottom of this door is about 23 inches from the floor due to the cabriole legs. The other factor, though, is that the cases will travel regularly to antique shows, so I thought tempered was a very good idea. Do you agree?

From contributor L:
Yes, I think the tempered glass is a good idea. The alternative would be safety glass (standard glass with a plastic coating glued to both sides), but that is 1/4" thick, so it will be heavier.

From contributor F:
What about lexan?

From contributor L:
Lexan will scratch over time. And with clients pawing the cabinet, it will be a short time.

From contributor A:
The purpose of tempered glass is so you don't get injured if it breaks, but it still breaks just as easily and is just as difficult to replace, if siliconed, as regular plate glass. If it breaks on the truck/trailer, who cares what kind of glass it has. If it breaks when someone is carrying it, they need to learn to be more careful. I have never had an incident of broken glass while being carried, although that could be because I always remove the doors before attempting such a feat. With that said, I do agree that tempered would be a safer bet. Better to err on the side of caution. My point was, if over 18", it is not needed. Tempered glass is heavy, and these things already sound like they are going to be fun to move.

Back to the silicone part. I don't like the wood retainer idea because it is more work. It takes me just as long to install retainer strip as it does to silicone glass in and clamp, if needed. By the way, the retainer I refer to is the flexible, I think silicone based, strips that fit into a very thin groove routed into the inside edge of the doors.

From the original questioner:
My assumption was that the door needed tempered because it is swinging, when I think breakage is most likely and most hazardous.

From contributor L:
Tempered glass is 4-8 times stronger than the same thickness of standard float glass. I don't think the weight difference is significant between the two same sized pieces of tempered and float; tempered is just heat treated float glass.

From contributor A:
I feel kind of stupid. If you stop to think, tempered shouldn't be any heavier than regular plate glass.

You are most likely to break glass by hitting it or having the door crash down, i.e. fall off the hinges. Tempered is more expensive, I know that much at least. I do not know what kind of margins you are looking at, but what I am seeing is a bunch of displays for which they are not willing to pay what they are truly worth. With that said, there is no reason you cannot go with regular plate glass. I won't argue that tempered would be a better choice in the off chance that someone did manage to break the glass and get injured. I am simply saying it is not required.

Tempered is stronger, I agree. Steel is stronger than wood, yet most of our houses are built out of lumber. Non-tempered plate glass, 1/4" thick, will be plenty strong for your needs. But, again, this is just my opinion. I have been known to be wrong before.

From contributor T:
I order all my glass tempered, any thickness. You can tell them to leave the temp logo off if you want. After years of ordering my glass from a local shop that just did a "belt sanded polished edge" - not great - I figured that somebody had to have a polishing machine like an E.B. A little research and luck with seeing a truck on the N.J. turnpike (this was 15 years ago before the web), and I found a cut to size, polisher/beveler, temperer, wholesaler 30 miles from my shop. I now do about $4-500 a month in glass. Just finished a kitchen with 16- 8 to12 lite doors, all 1/4" -1" bevel edge, temp, 112 pieces, about $18 each. Call C.R. Laurence - big glass hardware supplier. Find them on the web and ask them for the glass wholesale guy in your neck of the woods.

As for haunched m&t, siliconed and tempered, that is the way to go.

You don't say what hinges - Parliament style? Timberline locks? Lee Valley? Drill in propeller nuts for levelers in the bottom of the legs, since they will be moved so much. I have done dozens of museum and trophy cases through the years.

From contributor L:
We use all tempered glass. Wholesale cost is not all that much greater. They deliver it to our door every week, any edge treatment you want, any thickness.

From the original questioner:

Thanks, tempered it is (3/16" thick to save weight).

But I'd like to bring back the discussion to my other question, which is hardware. I will probably use three 2-1/2" by 3" lift-off butt hinges by Merit. Serious, heavy brass hinges, lift-off to encourage the movers to remove the door for trucking.

I still would like any ideas people may have for locking the door, as most cabinet locks are set into the edge for inset doors, whereas these will overlay the frame, to maximize the glass area. My best idea so far is a surface-mounted English style lock mounted inside the door. I will have to throw the keyhole off center in the 3" stile, or cut a relief rabbet into the 1-1/4" frame to allow room for the lock case. It's a little odd, I think, that there is nothing made for overlay doors, where the case side frame takes up nearly half the available width of the stile. I keep looking for something akin to chest locks, which grasp a protrusion in the strike, but which don't mortise into an edge.

From contributor D:
I always use retainer strips because they look better than anything else. However, you can put a bit of silicone in each corner, under the strips. You get all the rigidity you would want, and it's relatively easy to clean off if the silicone is only in the corners.

From contributor W:
This brings up a memory of a cabinet we did and had the same lock issue… I think what we did was use a typical cylinder lock with a hooked lever, something from Hafele maybe, but instead of it being on the door and locking into the case, I think we installed it on the side of the case and the lever turned and hooked onto a strike plate of some sort on the back of the door.

From contributor G:
If you don't like the look of silicone, we used to "pack" the glass in glass doors. Bed the glass in putty (what we used), then wedge the glass in place with plastic or wooden wedges placed on the end of the glass (you can work out which two corners take the load when it sags (or if even), then finish the glazing job with whatever you like - beads, beveled putty. I don't suppose you even need to bed the glass in the first place if it is interior, although I feel that some bedding helps absorb the shock.