Fire-Sanding and Coloring

By Michael Kehs March 6, 2024

Try a little woodshop alchemy

I’ve always had reservations about using exotic woods. While the colors and figure can be spectacular, the prices make it hard to experiment, or play. But what if I told you that you can achieve some of those amazing colors on local, more humble species such as poplar, ash, and oak to name a few? Before you accuse me of sorcery, read this story and give this technique a try. It is so easy that even the most timid beginner can produce stunning color in minutes. And what little black magic there is comes from a jar.

The secret lies in a multi-step preparation process followed by the application of a special product called Accent Paste. The prep involves sanding, burning, brushing, and sealing. The Accent Paste—available in a number of colors—is a soft, wax-based product that you apply with your finger to the prepared wood. The simple bowls I’m demonstrating on here will show you the basics, but the possibilities are endless in terms of colors, shapes, and surfaces. Experiment and be sure to let us know what you come up with.

Burn baby, burn

Turn your piece to shape, and sand it well to remove any tearout and to refine the surfaces. After carefully smoothing through 600 grit, inspect the surfaces before burning, as dings and cross-grain scratches will really stand out when you eventually apply the color. Then clean up your lathe area to prepare for using the torch. I use both a MAPP (or propane) gas torch as well as a smaller butane torch. Both are available at any hardware store or home center in the plumbing section. The idea behind charring the surface is to burn away some of the softer areas, increasing the texture. I suggest you practice first on scrap so you don’t inadvertently reduce your carefully turned bowl to a cinder. Note that torching laminated pieces can compromise the glue joints, so I recommend sticking with solid stock.

SAFETY ALERT

Warning, using a torch in a woodshop is dangerous. Thoroughly clean up all dust and shavings before you fire up.

More control. This smaller butane torch doesn’t burn as hot as MAPP gas and the pressure is lower, so you may find it works better for smaller pieces.

Texture to the forefront. A consistently burned surface creates pronounced grain texture even in mild-grained species such as poplar (left). In a coarser-grained wood such as ash (right) the texture is even more striking. Note that both of these bowls were dead smooth before torching.

Give it the brush off

Once you achieve an even char over the surface(s) of your piece, the next step is to give it a thorough brushing to cut back on the blackening and increase the texture even further. You may need to experiment a bit to find the appropriate brush. On softer woods, I find a brush with stiff plastic bristles works well. With harder woods, a brass-bristle brush often does the trick. Be careful not to add cross-grain scratches or to mar the surface by bumping it with the brush’s handle.

Follow the contour. Keep following the grain as you brush the inside of the bowl, this may require a kind of twisting stroke.

Good, clean fun. The brushed surfaces should have an even sheen to them. On softer woods such as bigleaf maple burl, I use the plastic brushes shown.

Polishing your act

Brushing will leave the surfaces highly textured, but also a bit rough. Now it’s back to sandpaper to tame the roughness. You don’t want to abrade away all the work you just did with the torch and brush, you just want to polish the high spots and ease the jagged spots. Thoroughly blow off the dust when you’re finished, and rub on a thin coat of a fast-drying finish such as Doctor’s Woodshop Pens Plus, or Myland’s High Build Friction Polish to seal the wood and get it ready for the color. (For product sources, see page 62.)

The blow off. After sanding, blow off the surface thoroughly to clean the dust out of the pores. You’ll see the surface transform from a frosted white to a clean brown.

Seal the surface. Dab the friction polish onto the surface with the lathe stopped (inset). Because the back of the bowl isn’t necessarily ready for finish, you don’t want to risk contaminating it as you might were the lathe spinning. Once the surface is coated, run the lathe to buff the finish and force it into the surface.

The glory work

After all that prep work, it is time to add the color. The accent pastes I use come in small plastic jars. When you’re shopping, be sure to get gilding paste, rather than patina paste, as the latter doesn’t seem to work as well. With the lathe off, use your finger to apply the paste, vigorously rubbing it into the pores. Then turn the machine on to burnish the surface and increase contrast. Burnishing will help force the paste into the grain, while also removing it from the high spots. The resulting surface won’t need a further finish.

Rub it in. I find it works best to rub in the paste with my finger. This way I can really work it well into the pores. It wipes and washes off readily afterward so I don’t look like a smurf the rest of the day. Power-buff to polish and set the color.

Add the second color. Rub in the next color, being careful at the edges to keep the colors separate. Fortunately, you can readily remove the paste from previously buffed areas as long as you haven’t pushed it hard into the surface.

Buff, buff, buff. With the lathe spinning at about 1800 RPM, buff the surface with a rag or paper towel. This is where you’ll be creating that beautiful mottled surface effect and remove any excess paste.