How to Grout a Ceramic Table Top
DEAR TIM: My wife wants me to build a wood table our family could gather around for feasts. She desires a contemporary design using ceramic tile with the tile inset into the center of the table. Have you done this before and what should I be aware of? Can I grout the ceramic tile since it's not secured to a floor or a wall? What type of grout? What can go wrong? Should I seal the grout? I want to get this right the first time. Victor H., Staten Island, NY
DEAR VICTOR: This sounds like a great project. Woodworking is very rewarding. I've built some tables using kits in the past and have always wanted to do one from scratch. Putting tile in the center of the wood table is a good idea. It's just one of many things you can put in the center of a wood table. I happen to have a wood coffee table in my office that has two miniature operating model trains that toot toot around under glass!
There are quite a few things you need to do to ensure the ceramic tile and wood play well together giving you years and years of pleasure. The first thing that comes to mind is make sure you purchase extra tile. You want to have these tile handy in case one, two or three of the tiles in the table crack or get chipped from an accident.
The ceramic tile need to lay in a recessed part of the table and be stable. Realize wood is an hygroscopic material and ceramic tile is not. This means wood can and does change shape and size in response to both liquid water and water vapor. Ceramic tile does not. If you glue the tile directly to the wood table recess, the tile may move and crack.
I would incorporate into your design a thin piece of crack isolation membrane. This material creates a buffer between the wood that wants to move and the tile that doesn't like to move. If you apply too much tension to the tile, it can and will crack.
Crack isolation membranes can be found at online stores that sell ceramic tile. You probably have a great ceramic tile store near your home since you live in a large metropolitan area that carries it. Home centers may require you to purchase a large roll and you only need a small piece. You may find a tile setter that will give you a scrap piece for free.
It's key to ensure the finished surface of the ceramic tile is at the same level as the wood at the edge of the table. Take the time to make this happen. If the tile is too high, the edges can get chipped if someone slides something heavy onto the table from the edge.
I would finish the table before installing the ceramic tile. The recessed area of the table should be finished with sealants and especially the shallow rabbet edge where the tile grout will contact the table. You don't want water from the grout to soak into the wood causing discoloration. What's more, you don't want any wood stain to soak into the grout ruining it. Apply extra coats of clear finish in this are to make sure the wood is isolated and protected.
If your grout lines are one-eighth inch or less in width, you can use wall grout that has no fine silica sand it in. I prefer to use slightly wider joints and sanded grout. The silica sand adds great durability to the grout.
When you grout, you have to be very careful where the grout touches the up against the wood table. If you use sanded grout, the sand can scratch the wood finish. Don't get any more grout on the wood than is necessary.
Your question about grout sealers is a good one. Years ago, I advised people to seal grout. I've come to learn sealers can sometimes cause more harm than good. In your case, I'd not seal the grout.
Sealers can do a good job of sealing the top surface of the grout, but they may fail on the tiny unseen crack between the tile and the grout. If red wine spills on the table and seeps into the grout between the tile and the grout saturating the grout just beneath the sealer, it might be a nightmare to remove the red wine stain.
I've found it's very easy to clean ceramic tile grout that's not sealed. A solution of oxygen bleach can easily penetrate ceramic tile grout that's not been sealed. You can spill all the red wine, gravy, salad oil, olive oil, butter, etc. you want on your new table grout and confidently make it look like new using oxygen bleach.
When you do grout, realize it's not easy to get professional results. The grout must be the right consistency, like that of cake batter, and you must wipe the joints with a sponge that has every drop of water squeezed from it. Too much water can cause grout to crumble and crack.
If you've not grouted tile before, I beg you to practice. Purchase some extra inexpensive tile and apply them to a scrap piece of plywood or drywall. Grout this tile until you become proficient. Then move on to do your new sweet table!