Filling a Void (December 2007)

Much like your navel, voids become a hiding place for dirt and lint, which is unsightly (and doesn’t win points with the opposite or same sex ,by the way). Voids can also be tripping hazards, and we all know how eager lawyers are to get paid.
And, if left to their own devices, voids just get bigger due to the lack of support on the edges, and continue to increase the problem by subtracting more material.
Enter fill – and, no, I’m not talking about Phil from accounting. It’s the collection of common everyday products that we can use to f-i-l-l the void. Depending on the stone, the application and how extensive the repair will be, your filling material may (and should) vary.

Case A –The Granite Countertop
So a homeowner chips a sink edge of granite with a frying pan, and they don’t have the missing piece (those pesky drains are no good for us repair people). They want us to fix it. What are we to do?
On our jobs, we reach for the CA glue. The CA (cyanoacrylate, pronounced sigh-ano-ack-relate) was actually developed by Eastman Kodak Co. for making gun-sight lenses for the U.S .military (it actually failed in that job) and later used to close wounds during the Vietnam War so soldiers wouldn’t die from the field to the hospitals. This exotic substance is known to most of the world by one of its trade names, Super Glue.
We’ve successful used CA glue to fix broken pieces of granite that resemble jigsaw puzzles to small repairs on travertine. It’s crystal-clear, which allows the minerals of the stone to shine through and gives the stone its natural 3D look instead of being a monotone patch. It also shaves nicely with a razor blade, and can be easily burnished.
The best thing I like about working with CA glue is the speed. When used with an activator, this glue will harden instantly, as in before-the-end-of-this-sentence fast. You don’t need to wait for it to harden before you work it, because it hardens instantly upon activation.
Caution – this stuff works and it works fast. Don’t get your fingers stuck together (or stuck to the stone) during use. It is advised to wear nitrite gloves when working with CA glue, so you can preserve your soft epidermis (and your intimate home life) because it can crust on your fingers.  Always keep a bottle of de-bonder on hand as well.
So why not fill anything and everything with CA glue? First of all, on large fills (like a travertine floor), it’s not cost-effective. The good stuff runs about $10/oz.; on small repairs, time is valuable, but on bigger jobs requiring a lot of fill, $10/oz. becomes like gold.
CA glue also works in thin layers only. Once the activator hits it, it creates a crust over the top layer and effectively seals the liquid below in the void, much like the cap on the bottle. This would play havoc if tried on large areas with deep voids
And, CA doesn’t work when coloring comes into the picture. Adding tints and dyes can activate the glue, causing it to harden too soon (and with an ugly color) and/or cause a nauseous chemical reaction.
Having said that, one way I’ve found to tint CA glue in a crack without major problems is to fill the crack with a slower-drying formula and then pour some crushed stone (powder consistency) of a similar nature over the valley. As the particles enter the glue, it somehow acts as a catalyst and hardens. You shave (or grind) off the excess and then refinish
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Case B –The Travertine Floor
I’ll never forget this older southern belle in her condo in Alabama asking me (imagine the twang) “How do I keep these holes from coming back in my travertine?” My reply to her was smooth, quick and direct: Stop walking on your floor.
She was a bit surprised at first, but after taking a spare tile from the box in her attic, and showing her how the stone was full of voids and wear naturally revealed new ones, she understood.
How do you fill travertine? You have two choices –unsanded grout or polyester resin (FYI – traverfil is unsanded grout with cream of tarter added to slow down the curing process). Unsanded grout = easy. Polyester resin = very effective, but messier (and charge more money for the job to live with the added effort).
The secret to any good fill job is in the overfill. Without leaving enough fill material over the top of the hole to allow for shrinkage, your fill job will resemble a beaten old copper pot. There will be more divots in that floor than the back nine at the local public golf course. Think about this: The reason grout is normally recessed is not because it’s put in there recessed – it shrinks to that level as it cures.
Another point to ponder is where does any excess water go? It always takes the path of least resistance to the lowest possible plane; if your fill is recessed, dirt will travel in mop water to the filled areas and create unsightly craters much like that fuzzy navel at the beach (and I ain’t talking about an alcoholic beverage).
It doesn’t matter whether you are filling with grout or polyester – you’ll have shrinkage, so you must account for it. Either overfill the voids, or run the chance of not getting a full payment of your bill.
A proper fill job will allow the floor to look smooth and monolithic. This makes for happy customers and paid bills.
Speaking of paid bills, I’ve got to run to keep them coming in the door. Until next time, keep your stick on the ice.
Tom McNall is founder and owner of Great Northern Stone Care, a Huron Park, Ontario-based stone-cleaning and -restoration company servicing all of southern Ontario. He also serves as the director of training, technical assistance, and operational support for Stone Restoration Services, a division of Stone Shop International. Tom offers corporate and private consultations, serves as a trainer for the Marble Institute of America, and is also on the organization’s board of directors.