I’m building some cabinets for an art dealer. They want to use the tops for display space. The idea is that each wood countertop will have an unframed sheet of glass lying on top of it. They’ll lift the glass to spread out prints or photos or similar flat artwork, and then put the glass down again. I’ve never built something exactly like this before, so I’ve been checking out other furniture with glass on top. They almost all have little spacers between the glass and whatever’s under it. The spacers are typically the diameter of a nickel or so, and as thick as a dime or so. They may be cork, felt, or plastic. They don’t have adhesive on them. They’re thin enough and usually far enough apart that the glass sags down to touch the wood between the spacers — particularly if somebody puts anything down on the glass.
My question to you all is “What the heck are those spacers doing?”
Replies
This is just a shot in the dark, but I'll bet they put them there to keep the glass from sticking to the varnish or whatever finish they used. If the finish softened and then dried with the weight of the glass on it, it would create a good bond and trying to remove the glass would result in breakage. (???)
Jeff
Built several pieces with glass overlay on wood tops. The glass is very tough and easy to clean, and shows off the wood underneath.
However, it will bond (somewhat) to most finishes especially if cleaner (Windex) gets underneath the glass. Sets up kind of a suction so you have to slide it off. Oil or wax finishes tend to smudge it if it is moved around with no spacers. It will show off any irregularity in the flatness of the top too.
Be sure to have your glass guy put a "polished fingernail edge" on the glass. Wouldn't go any thinner than 3/16". Use the thin round clear bumpers.
You might consider building in a raised profile on the edge to trap the glass sheet and hide the edge.....
Tom, if the edge is hidden with your suggested raised profile, cannot the pencil edge be ommited? I've found that the edge treament adds considerably to the cost of glass.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I would not omit the pencil edge. The rough edge from scoring and breaking is too dangerous to be used on a display case. One tiny little sliver in a customer's hand can cost a lot more than grinding a safe edge on the glass. If the glass were mounted in a frame, and the frame opened up, that would be a different story. The cost would be paid by your client, anyway.
You've still gotta move the glass to clean under it occalionally and the finished edge makes it easier on the fingers. I always put on cotton gloves when handling these tops to keep from getting smudges on the under side.
Good point Tom. I tend to skimp on these things when ordering glass for my own use, but I certainly agree that when it's going to another person caution is in order.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
In addition to the possibility of finish stickiness there is a possibility of the photos or paper sticking to the glass if compressed, especially if they are glossy finishes. Happens a lot in picture frames also.
Many do not realize that almost all finishes never really stop curing. They cure for years and years. This is particularly true of oil based finishes. As they cure the emit gases (reason not to use oil based products inside drawers or cabinets) and these gases get trapped under the glass and somewhat liquify. This leaves what looks like liquid smears on the bottom of the glass. Raising the glass slightly lets the gases escape.
In addition, two very smooth surfaces in close proximity have an attraction to each other. This makes them tough to move or lift apart. Try putting two sheets of glass together and you will see the affect.
Others have answered your question. My comment has to do with safety and utility. I'm not sure how large the glass is, but it's probably large enough to be heavy. If someone lifts it with their hands, it'll get smudged and depending on size it might break. How about having some sort of frame around the glass so that it can be hinged in back and have some sort of handle in the front, so lifting would be a piece of cake? The handle could actually just be the front part of the "frame", with some sort of finger pull profile.
Just thinking out loud here.
John
Thank you all for the explanation of these spacers.
Several of you have wondered about the glass going all the way to the edge of the countertops. The idea is that fluid spilled on the glass will go over the edge on to the floor. If the glass were inlaid into the top, the fluid would tend to drop through the vertical crack at the edge of the glass to attack the art underneath.
Jamie
Jamie,
They're there to ensure that the glass doesn't touch the tops of the skirts.
Part for ease of finish, also (mainly) to ensure that the glass doesn't break - if there was a grain of sand or a bump on the top of the apron, any weight put onto the glass would ensure that the glass was bent around a sharp radius, which initiates fracture.
cheers,
eddie
Unless you have a large overhang, fluid will tend to run under the glass at the edge. I know this from experience.
Glass alone won't prevent liquid from flowing underneath. I'd still recommend some sort of wooden frame, hinged in back, and if liquid is an issue you can make the glass at the same level, caulked, much like a trivet. The wood edge could be cut to make the liquid fall to the floor, not underneath.
John
Jamie,
You should be using tempered glass for the counter tops, it is much harder to break and when it does it doesn't produce large razor sharp pieces, just gravel sized chunks.
By the way, glass isn't especially hard, it scratches quite easily. If you look at a glass countertop in a store, you'll find it heavily scratched in the areas that get the most traffic, especially near the registers. It can get quite ratty looking after a while.
Having people regularly handle unframed sheets of glass is a formula for disaster. I'd suggest mounting the glass in wood frames, somewhat like a picture frame. The whole frame and glass could be lifted off or even better, tipped upward with hinges on one edge to get access to the area underneath the top. Provide a prop rod or a chest lid support to hold a hinged top up while it is open. The wood frame should overlap the sides of the cabinet to keep out dirt and liquids.
Glass cleaning liquids can attack wood finishes, I think that polyurethane is the most resistant.
Hope this helps, John W.
on top of what the others have stated they can act to reduce vibration transfering through the case to limit rattle. The spacers also reduce tension created by a vacum like effect in case of repeated removal of the glass.
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