Nothing catches the eye like a big ole scratch or chip right in the middle of an otherwise beautifully finished wood surface – except, possibly, a failed repair attempt. Below, Michael Dresdner outlines two of the most time-honored finish repair methods in answer to a Woodworker’s Journal eZine reader who’s having trouble getting the invisible fixes he’s after.
Q. When the finish (lacquer or varnish) on a tabletop or dresser is chipped down to the bare wood, what is the best method to repair this damage? Usually these chips are 1/4″ wide and 1/2″ or 1″ long. I have a light- colored mahogany dresser with three small scratches and have tried padding lacquer, but it doesn’t level the scratch to the surface. What can I use to bring the surface level and smooth? I have also tried shellac sticks but am not satisfied with the finish these leave or with the color. Can the so-called wax sticks be used for this type of repair, and will the topcoat finish of varnish, lacquer or Varathane® adhere to these waxes?
A. Michael Dresdner: “There are two good techniques for filling chips. The faster one requires more skill, while the simpler one is slow and tedious.
“The classic quick method is burn-in stick (sometimes called stick shellac, though modern sticks are of other resin combinations.) Sticks come in a wide range of colors including clear and translucent amber, so with a deft hand and some experience, you can indeed get a very good match. I suspect your dissatisfaction with them could be attributed either to lack of experience (they are not particularly user-friendly, and take quite a bit of practice to get good results) or a lack of access to the proper color assortment.
“The other method, called ‘doping in,’ is both slower and somewhat easier. Use a small artist’s brush to fill the voids, a few drops at a time, with a fast-drying spray lacquer. Use clear, or if color is needed, tinted lacquer. As the lacquer cures, it will shrink substantially. Come back each day and add another drop or two, letting each day’s addition cure fully before you continue. Depending on the depth of the chip, this method will take several days or longer. Keep filling until the lacquer sits just slightly proud after it is cured and hard. Sand the area flush to the surrounding finish using 600 grit or finer sandpaper wrapped around a small, stiff block.
“No matter which method you use, burn-in stick or doping in, the repair will look much better if you add another topcoat of whatever the finish is to blend the sheen of the repair.
“I doubt you will be happy with a wax stick repair. They are opaque, and while they will hide chips in obscure, hard-to-see areas, the repair will be very obvious when viewed head-on, as on a tabletop. In addition, most coatings will not cure over wax stick.”
From the Woodworker’s Journal eZine archives
If you decide to try your hand at the burn in method, you’ll need, at minimum, a burn-in knife and burn-in stick. We recommend practicing your technique on a piece of finished scrap before you take after the neighbor’s Steinway. For best results, consider picking up a tin of heat-resistant Burn-In Balm. Wipe a little on the areas surrounding the repair to avoid overheating the finish and turning a small defect into a major blemish.
For doping-in, try a few drops Brushing Lacquer applied with a Sable Touch-Up Brush as directed above. With either a burned in or doped in repair, absolutely invisible repairs can be achieved by applying a coat of a compatible clear finish to the entire surface as a final step.