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Fixing Flubs with an Artist’s Flair

Jun 18, 2016 | Expert's Corner | 0 comments

Finishing is the process of transferring liquid out of its container and onto a project using a brush, rag or spray gun. Sounds simple, but doing so flawlessly can be easier said than done, as many of us discover.

Fortunately, fixing our errors isn’t overly complicated. Moreover, it’s often fun, as you get to stretch your artistic wings with some custom coloring and detailing. But it’s better to avoid problems in the first place – specifically those related to wood preparation – so let’s start there.

Many woodworkers believe that wood from the home center’s rack or fresh from their thickness planer is ready to have a finish applied. Sorry – it’s only ready to be handplaned or sanded. See for yourself: sight down a plank illuminated with a strong backlight. What you’ll see are rows of tiny ridges left by the planer’s blades.

Splash some methyl alcohol onto the board, and those ridges will stand out like the Rocky Mountains. And that’s how things will look when you apply your final finish. Remember: applying a finish only makes surface flaws more obvious. So prepare any flat panels with a handplane, which gives a superior surface, and get ready to sand the rest.

I’ll confess that I hate sanding. It’s messy as all getout and ranks right up with The Shopping Channel for nonstop excitement. And at first I only made this worse for myself by buying bargain-bin sandpaper – the grab bag stuff they sell at wood shows. Most of the grit fell off before it did much damage to the wood, so I learned my lesson: buy from manufacturers who aren’t afraid to put their names on their products.

Next I learned something about using random orbit sanders. My habit had always been to move the sander in an easy figure-eight pattern at a rate of about one foot per second. Now when I checked my work with the backlight what showed up were the marks from the planer plus a bunch of squiggles and pigtails scratched into the wood by the abrasive. I wasn’t giving the sander a chance to do the work.

A rate of a foot about every 10 seconds is more like it. Honest. And it really takes getting used to – it feels like you’re deliberately working in slow motion.

At the same time as you slow down your rate of sanding, keep in mind that it’s false economy to “get your money’s worth” out of every sanding disk by using it until it’s worn bald. You’re wasting your time by using a disk for longer than about four minutes. You can actually feel its aggressiveness diminishing until it isn’t doing much more than burnishing the wood.

A disk may wear out even faster on softwoods, as it loads up quickly with resinous particles. The same happens if you try to sand a finish that hasn’t fully cured: the abrasive becomes coated with tiny balls of finish that leave behind scratches of their own.

By the way, “dry” isn’t the same as “fully cured.” “Dry” means that the solvents bearing the finish have evaporated. “Fully cured” means that all chemical bonding and interlocking of molecules is complete and the finish is hard. The difference shows when you オンライン カジノ sand: a fully cured finish will come off the sandpaper as a fine dust.

You can reduce the time spent sanding by starting with the right mobile casino grit for the job. If you’re sanding a board that has come from the thickness planer, you can probably start with 120-grit. If there’s tearout from the planer, 80-grit is better to start with, then move on through 120-grit.
Tip: Vacuum thoroughly when changing to a finer grit. You don’t want to be pushing coarser grit around while trying to smooth the wood with a finer one.

From the 120-grit disk, change to 150- or 180-grit and sand thoroughly. If you’re working with hardwood, that’s probably good enough. If your project is softwood, continue through 220-grit. Use a backlight and alcohol to find scratches left by coarser grades of sandpaper. Plane, scrape or sand them out. The alcohol will also help reveal areas of glue squeeze-out. Use a card scraper to remove any streaks.

Now that you’ve prepared the wood properly, apply a first coat of finish and inspect for flaws. These might include hairs or bristles, dust, raised grain or a lighter-colored area of sapwood. You may have to disguise a knot, an area of tearout or a plugged hole whose grain pattern isn’t a good match.

Put on your critic’s hat. Search for distractions, and be thorough. It’s tempting to think, “Good enough.” That probably only means it’s not good enough. Now is when you need to slow down and do things right.

Any errant bristles or hairs you find while the finish is still wet can be plucked from the surface with tweezers. If the finish has dried, slice under them with your sharpest chisel, then use some finish on an artist’s brush to fill the excavation, and carefully sand by hand to blend the damaged area into the rest of the surface. Additional coats of finish should take care of the rest.

Gremlins live in thickness planers. You can depend on them to tear out a chunk of figured grain on what was to have been the last pass through the machine. If you continue planing you’ll make the workpiece too thin so you’re forced to fill the defect.

A wax fill stick works for tiny オンラインカジノ日本 flaws, but for surface repairs that are a bit larger, sand a piece of the same wood as your workpiece using 220-grit paper until you have a small pile of sawdust. Put a drop or two of cyanoacrylate glue into the defect, fill it with sawdust, pack it smooth and add another drop or two of glue. A quick shot of accelerator will cure the glue in seconds; then you can sand the repair smooth.

Fix larger defects the same way but use epoxy instead of CA glue for better gap-filling capability.

Repairs like this will stand out visually from the rest of the wood so you must camouflage them. Use fine artist’s brushes and any combination of stains, dyes, artist’s pigments, and touch-up pens. The intent is to break up the shape of the repair so it blends into the surrounding area, tricking the eye so what it sees appears to be normal variations in the wood’s grain and color.

Here’s where you get to be artistic. When blending and shading color, an almost dry brush gives the best control, so paint most of the stain out of the brush onto a paper towel or scrap of cardboard. If you do put too much color onto the wood you can usually wipe it off again so long as you’re quick. A rag dampened with the appropriate solvent is also good to have on hand.

Artist’s brushes with their bristles trimmed to stiffen them a bit work well with this dry-brushing technique. Use them to disguise areas of plain color by adding dabs, stipples and streaks. The other brushes you’ll need are very fine sable or Taklon brushes used for detail work. You’ll find these brushes plus artist’s pigments at any quality art supply shop.

Don’t try to fill areas with a single color. If you look closely at wood you’ll see there are no areas of plain, bland color. Instead the surface shows a myriad of tones, lines, shadows, specks and so on. To replicate this, use a “pointillist” technique with your brushes – dabbing and spotting little specks and streaks of color until the shape you’re repairing begins to lose its form and blends into the surrounding wood.

Use the same technique where you have plugged screw holes. Even tapered plugs often show as a faint circle in the wood. By breaking up that circular line into random spots the eye will no longer be able to pick out where the plug is. Just a few flecks and streaks of a darker color applied with a detail brush will interrupt the plug’s silhouette enough to make it invisible.

Another common repair is to darken light-toned sapwood in species like cherry and walnut so it better matches the darker heartwood. You can blend stains or dyes to match the heartwood’s color, then use an almost-dry brush or a rag to daub or “paint” the sapwood, gradually blending the colors until they match. If you have a spray system, this is the place to use it since it gives you excellent control over color and shading.

Blending stains to create the colors you need is easier if you have a small pane of glass handy. Lay it on top of the wood to be stained and blend your colors on it. The transparency will help show how the stained wood will look when you apply the color.

Your best matching system, however, is to use scraps of the wood used to build the project. Make a batch of test strips, then experiment on these sample pieces until you get your alterations right. After you finish a piece, label the sample strips and store them – just as you would do with a jig. Then the next time you build the piece you’ll have an a-b-c record of your finishing steps and you won’t have to re-invent the wheel. Have fun!

About Bill Perry

A self-taught cabinetmaker with more than 35 years of experience, Bill Perry designs and builds custom fine furniture and Windsor chairs at his workshop – Wm Perry Studio – in Toronto”s Leaside district. He also delivers private instruction in woodworking techniques.