How To Repair Knots In Wood

Let's face up it, none of united states of america are perfect, and neither is wood. Knowing how to repair defects is critical to the success of whatever job. Many projects need repair or touch up in some form or another, whether it's a small knot or check, or when our own short comings in craftsmanship reveal themselves, like on open seam or the mistaken drop of a hammer.

Whatsoever the cause, in this two-indicate series, I will explain a few uncomplicated tricks to repair these blemishes. These techniques tin can be used for raw or finished wood.

I pause these issues into voids, similar an open up joint or check fissure; and colour changes where the wood or repair needs color touchup. In role two, I will cover color repairing and fixing lacking finishes. There are a larger variety of types, causes and remedies – too many to comprehend here – simply this information volition get you through some major ones.

Information technology'due south ever all-time to endeavour and make full a void with matching woods, similar in an open seam or articulation. Filling it with a thin slice of veneer or sliver of wood and gluing information technology is my kickoff choice, only about of the time, defects are irregular in shape or likewise pocket-sized for inserting wood.

Open up knots or checks, big or modest, are really the easiest to fix every bit they are already a visible and accepted defect. Because these knots are darker than the surrounding wood, filling them with a matching or darker color is typically all that's needed.

Before any repair is done, I seal the wood with a calorie-free coat of wax-gratuitous shellac that brings out the final color of finished woods, considering it aids in color matching. It also helps with adhesion and protects the surrounding surface area from excessive filler. Always do a color examination on a sample board outset.

When using wood fillers, information technology's vital to make sure that the surrounding surface grain doesn't get filled or clogged with excess filler. This is the about mutual mistake, and leaves a halo of filler around the repair. To avoid this witness line, record off the surrounding surface area before applying the filler. The tape volition as well act as a raised ledge for solvent-based putties, leaving it slightly high later on application and allowing for shrinkage, if there is whatsoever.

The woodworker's underground

There are many types of fillers that work just fine. They may differ in curing or drying fourth dimension, expense, smell and available coloring options. Since I like to keep my projects moving and hate to watch the grass grow, automotive putty is my pick for large voids.

Fill small holes with a solvent-based putty, taping around the defect for a neater job. — Make full small holes with a solvent-based putty, taping around the defect for a neater chore.

Bondo, for example, is polyester-based putty filler catalyzed with a two percent hardener of benzoyl peroxide. The hardener has a toothpaste-like consistency and comes in three colors: reddish, white and blue. I avert bluish because it adversely furnishings pigmenting or over-coloring. Red is okay when my forest are brownish in color, but white gives me the most pigmenting flexibility. Minwax makes a polyester-based filler with a tan coloring.

A downside to polyester fillers is the olfactory property. It has a stinky olfactory property due to the styrene solvent in it, and I don't recommend using it inside a house or basement.

To become a ii percent mixing proportion, use a golf-ball sized blob of Bondo to a 1" line of hardener. One time thoroughly mixed, information technology will prepare in 5-x minutes at 70 degrees F, and is then ready for sanding and finish. Polyester pigments or Blenall powders tin can be added and mixed in to adjust the color of the putty to closely match your woods.

You can also use epoxy to fill holes only the set time is much longer, typically one to 12 hours. I don't recommend using five-minute epoxies as I have found them besides soft and sticky when trying to sand. Urethane is a great quick-setting selection merely not always readily bachelor.

Automotive filler, epoxy and urethane don't shrink. Most other filler options accept solvents, such every bit acetone, booze or h2o, which crusade shrinkage as they evaporate. To gainsay shrinkage, apply the filler proud of the surface or utilize two coats.

Scratching in grain texture helps guard against a repair that looks too slick and shine, which is another common mistake, particularly with large voids.

For smaller voids like sparse cracks and pinhole knots, wax is great mode to go. Wax comes in a variety of colors and a few hardnesses. For very small voids no larger than ane/xvi", I like to use rub-in blending sticks. In a pinch, crayons will work. Simply rub it in or use a heat gun to cook the wax and baste it into the void. Subsequently information technology hardens in a few seconds, remove the surrounding smear by rubbing the wax flush with a hard block of wood wrapped in a cotton wool rag and a few drops of mineral spirits.

There are harder low-rut wax sticks that are meliorate for slightly larger voids, i/eight" to 1/4" in bore. These waxes are hard plenty to prevent a fingernail from pushing in and require a estrus gun, iron or open up flame to melt in place. One time they ready, utilise an old credit card every bit a scraper to affluent it down, then buff with spirits and a material.

All of these wax crayons come up in a diversity of colors and it is typically better to err on the darker side. These specialty waxes will fifty-fifty have a sprayed end without fish eyeing.

Solvent-based putties like Famowood or DAP woods dough are good for minor holes and swell for edges and corners where wax won't have the structural integrity needed. These come in a diversity of colors and tin can be intermixed to conform the color and dry quickly.

For better adhesion, add together a minor drop of white glue to the mixture, which volition too work with water-based fillers. For very fine seams, you can create a simple home mixture of fine sawdust and shellac or PVA glue.

Accent instead

Every bit an culling, instead of trying to hide a defect, y'all might consider accenting the natural blemish with a contrasting inlay using colored wax, pigmented resin, and mineral or metallic dust.

Filling a void with crushed turquois and mother of pearl or copper dust is easy to do. Simply fill the minor void with the dry powder and adhere with CA gum. Once ready, it can be sanded flush and finished. For larger voids, add epoxy to the mix. If the void is really deep, fill with resin until left with a pocket-size void, and then apply the accent pulverization. Typically a second coat of fine powder is required to fill up any remaining pinhole air bubbles.

The terminal type of void that needs filling is a dent. In these areas, the color and grain of the woods is intact and filling with pigmented filler will cause more of an obvious blemish. Outset, I effort steaming the divot with a few drops of water and an fe. Often this volition swell the woods, and once sanded dorsum flush, the color and texture matches perfectly.

If the paring still remains, fill with any articulate resin, which allows the surface to be flush and the colour to show through from below. I like to use a UV or blue light-catalyzed resin like BluFixx, which is a pen that has a squeeze dispenser on one end and a bluish light on the other. BluFixx comes in a diversity of colors. I similar articulate and black for knots.

Lightly sand the void with 220 grit, and then add together a few drops of resin to the void. Apply a piece of clear packing tape and squeegee the resin flush with a putty pocketknife. Shine the blueish light through the record. It volition prepare in nigh x seconds. Remove the record, sand flush and yous're proficient to become.

Scott Grove is an art article of furniture maker, sculptor, and YouTube personality who selectively teaches and lectures, most notably at the Marc Adams School of Woodworking and The Chippendale School of Furniture in Scotland. For more than, visit www.imaginegrove.com and www.scottgrove.com.

This article originally appeared in the March 2022 issue.