I usually post in Breaktime, but I figured the furniture builders would be better for this question.
I am doing some remodeling work for a client who has an oak coffee table with an inset glass top. The glass top ( ~20″ x 48″ x 1/4″) sits down in a picture framed top surface. The other night she was awakened by a loud noise and finally discovered the source of the noise was the glass top breaking. So, she has asked me to replace it.
The glass broke down the center of the long dimension – 2 pieces ~ 10″ x 48″. The glass was anchored in its recess by what appears to be clear silicone caulk around the entire perimeter. In its broken configuration, the glass is “tented” up at the crack.
The table had been in her beach house (humid) for 5+ years and was moved to her inland house several weeks ago (dry – we are currently in the heating season).
I theorize the glass broke due to the table drying and shrinking (evidenced by the tented condition of the glass). Makes sense as the table is solid, sawn, white oak across the width.
I ordered new plate glass yesterday and am looking for advice as to some sort of sealing material for the edge of the glass. I would have thought that silicone would have enough “give”, but evidently not. The glass to wood clearance is roughly 1/8″ on all sides.
The glass may have been siliconed in place while the table was in a swollen state and that is what got us. May be fine if the new glass is siliconed while the table is in a dried state. Silicone stretches better than it compresses? Your thoughts, hints, experiences appreciated.
Jim
Never underestimate the value of a sharp pencil or good light.
Replies
There are wood movement charts posted somewhere in these forums and if the table is wide enough, 1/8" might not be enough clearance although this gap may be enough now that the table has shrunk to its minimum.
I can't imagine that with 1/8" gap (in ALL locations?) and silicone that there is enough stress to fracture glass. Glass is "stronger than steel" of equivalent size. I rather suspect that some old, manufacturing induced stress finally did its work.
One night at dinner my wife and I heard a "crinkling" sound. In the next roon, a large window was slowly destroying itself before our eyes. It "just happened".
With glass table tops I take the furniture to the galss shop and tell them to fit it. Dimensions-only, don't cut it.
Jerry
I would tend to agree with you except for the following.
When the glass fractured it raised itself and a pile of magazines roughly 1/4" along the crack and stayed in that "tented" condition.
One of two things happened - wooden table shrunk (likely) or glass grew (unlikely).
Jim
Never underestimate the value of a sharp pencil or good light.
Gretchen, Bill, Dave, et al,
Thanks for your input on this problem. Picked up the new tempered glass (edges polished) today at our local glass supplier.
Quizzed the sales person on this issue - she looked at me like I was crazy when I asked what they suggested in terms of installation. She gave up and got me one of the glaziers (sp?) from their installation department.
After asking about edge gaps ( 1/8"+), he suggested any one of 3 solutions:
1) let it float directly on the wood lip. - will move slightly in use, no dirt seal.
2) apply felt strips to the lip and float the glass - will still move somewhat, better dirt seal.
3) lay glass directly on the wood then seal edges only with silicone. - he suggested using option #1 for another month then remove glass, clean thoroughly, replace glass, seal with silicone. His rational was that the wood will stop shrinking in another month of heating - if the wood swells in the summer the silicone seal may fail but the glass will not break.
Option #3 sounded the best to me as it will provide a permanent dirt seal and at least a bit of protection from liquid spills (owner's grand kids).
Thanks to all!
Merry Christmas! (preferred by 69% of U.S. polled) Happy Holidays! (#2 choice).
Jim
Never underestimate the value of a sharp pencil or good light.
Hi I hope I can help you with this as I have put a lot of glass inserts in coffee tables among other things to mention a few and NEVER had one break due to stress.Don't seal it in any way.Just put a thin felt strip around the edge for it to rest on.I think there may have been some human negligence to cause this breakage.With a 1/8 clearance around the table there is no way any kind of shrinkage should break the glass.Good luck and have safe and happy new year.
Ken
We have a coffee table with a glass insert top but the glass isn't "anchored". Ours just floats in the recess and there's some decorative woodwork under it to provide some additional support.
I would bet that the silicon adhesive prevented the glass from contracting with the wood and that's what broke it.
I would take the table to a glass shop and have them make a new insert using at least double strength glass and preferably safety glass. Size the glass about 1/8" smaller all around and don't "glue" it down - just let it float.
Jim, the glass may have been stressed by something other than the wood shrinking. For instance, the movers may have bumped it slightly which started a crack. Since the crack went fairly straight, the glass was not tempered. Tempered glass would be much stronger and able to withstand most stresses. My guess would be to let the glass float on little clear plastic bumpers. For the size of glass that you are talking about, I would consider 3/8" glass since it's lying flat and will have things set on it. But since the recess is already cut for 1/4" tempered will be alright. These are my guesses.
Good luck and Merry Christmas to all.
Bill Lindau
Are you getting tempered glass? Just a thought.
Jim, try just silicone in 2 spots, one on either side of the table, opposed each other. The wood can shrink without effect on the glass. aloha, mike
The glass was anchored in its recess by what appears to be clear silicone caulk around the entire perimeter
Old BrillCream Advertisement .... 'Just a DAB will do ya!'
Jim
When I make furniture involving glass, I always use tempered glass. Also, for table tops or shelves, if you use the small clear plastic/rubber stick-on feet/bumpers, the glass will 'float' and not be joined to the table. This combination will surely prevent this from happening again. They're the same bumpers I use for cabinet doors.
If somebody else said this already, then oh well. I didn't read all the posts.
Jeff
No reason for the silicone at all. If you must fill that gap, use felt strips.
DR
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