THE WASHINGTON POST – Q: Our only granddaughter inherited a table from her grandmother that my wife and I had given her. It was made in Mexico, I think from rocks and acrylic. It normally sits on legs with a piece of plywood cut into the same shape as the tabletop. But during a move, the tabletop fell over and cracked into two pieces. The break was quite clean. It has a lot of sentimental value. Can it be repaired? Or is it done for?
A: Yes, the tabletop probably can be glued back together. If the break is clean, then it bodes well for a good repair.
The table appears to be not just clear plastic and stone, as you suggest, but also iridescent chunks of mother-of-pearl from abalone shells. Although the plastic could be acrylic, it might instead be epoxy, urethane or polyester resin, all of which come in formulations suitable for casting into a mould.
“From the cured pieces, it’s impossible to know what the resin is,” said General Manager Fred DeSimone of Hapco Inc, a company in Hanover, Massachusetts, that makes a variety of casting resins and adhesives. “Nobody can tell what it is without doing a chemical analysis.”
He and several other sources said your best bet is to find a clear epoxy that doesn’t set too fast and that comes in larger quantities than the syringe applicator tubes that take up most of the display space at home centres and hardware stores. One suitable product is Z-Poxy 30-minute clear epoxy.
You’ll also need wax paper, disposable gloves, a small disposable measuring cup with ounce gradations, a stir stick, an acid brush (sold with plumbing supplies, this type has a metal handle and stiff plastic bristles, which you can shorten with scissors to make them even stiffer and more suitable for spreading thick epoxy), denatured alcohol and paper towels or clean rags. You’ll also need a sturdy work surface and an assortment of clamps.
Although it’s theoretically possible to glue a joint with epoxy simply by pressing the pieces together and leaving them undisturbed while the adhesive cures, you could accidentally jiggle them apart while you are cleaning up excess glue. So take the time to rig up a clamping system. Because the table edge is curved, you can’t run clamps directly across to pull the pieces together; the clamps would slide.
One solution is to clamp pairs of handscrews – the old-fashioned clamps with wooden jaws that you open and close by adjusting a pair of threaded rods – to the outside edges of the mating pieces. The backs of the jaws then provide a flat clamping edge for bar clamps that pull the pieces together. Lee Valley Tool Company showed pictures of this setup in a recent newsletter, which you can access at leevalley.com by scrolling down in the Discover section for the woodworking article called Clamping Techniques for Oddball Glue-Ups.
Or you may be able to secure one piece of the tabletop to a workbench with C-clamps (cushioned where they fit against the tabletop) and clamp a board close to the outside edge of the other piece; then use wedges between that board and the tabletop edge to exert pressure.
Many glues work best if you first roughen up the mating surfaces with sandpaper, but that is not necessary with Z-Poxy, said Frank Tiano, owner of Frank Tiano Enterprises, which supplies the product to East Coast retailers in the United States (US) and also sells it from its website, franktiano.com. However, it’s very important to make sure the edges are free of dust, bits of stone or shell, or other debris. “The most important thing is to have intimate contact with the two pieces,” Tiano said. “When you put them together with no adhesive, it should look wonderful.”
When you’re ready to glue, first spread wax paper under the area where epoxy might drip out. Then mix the epoxy components thoroughly. Using the acid brush, dab and spread the epoxy over both mating edges. “Just a film,” Tiano said, “not gooey, gooey.” Work quickly, because you have only 30 minutes of open time with the epoxy.
Push the pieces together and clamp them. Excess epoxy will ooze out along the joint. Wipe off the bead with a paper towel moistened with denatured alcohol. “Wipe it over and over without letting the alcohol run into the crack,” Tiano said. Switch to clean paper towels as needed, so you don’t leave a film of epoxy on the tabletop. Any residue you leave will be there permanently once the adhesive cures.
Although the epoxy hardens in 30 minutes, it takes longer to cure and develop strength. The tabletop should be left undisturbed for at least several hours. Tiano said that if it were his table, he would leave it untouched overnight.