Introduction: Wood Finishing
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About: The official instructable for Popular Mechanics magazine, reporting on the DIY world since 1902.
One of the easiest and cheapest ways to give your apartment or home a renewed look is with finishing. Upon the first touch of a rag or brush, furniture comes alive and the true character of any wood grain is emphasized. Finishing also adds protection. It is designed to inhibit the transfer of moisture and to prevent the surface from being contaminated by dirt and stains, adding to the life of your furniture.
To pick a suitable finish, you'll have to shop through a multitude of products with varying characteristics. The most common finishes are shellac, lacquer, varnish and oil. These are all solvent or oil-based products, so make sure to take precautions. Wear protective gloves, goggles and a respirator with organic vapor cartridges when using these materials. Most importantly, make sure your work area is ventilated according to the recommendations printed on the produc's container.
One of the biggest differences among the four traditional finishes is how they function on wood. Shellac, lacquer and varnish are all surface finishes. This means that they do not penetrate, to any great extent, past the surface of the wood. The first coat goes in the farthest, but subsequent coats merely build on the first to form a smooth, usually glossy, surface. Oil, on the other hand, is considered a penetrating finish because it reaches much deeper into the wood and leaves only a microscopic layer of finish on the surface. Subsequent coats continue to penetrate.
All these finishes have their strengths and weaknesses. Shellac, for instance, when properly applied, creates a stunning high-gloss surface, which, over time, takes on a remarkable amber color. It's also very fast-drying, which is a great advantage over some other finishes. Unfortunately, shellac is very prone to water stains.
Lacquer is also quick-drying and is the preferred finish of many professionals. It's usually sprayed on and yields a clear, hard finish that stands up well to practically any abuse. It is, however, very flammable.
Varnishes, both the traditional types and the newer poly-urethane versions, are extremely durable and some impart a warm amber tone, not unlike shellac. Unfortunately, varnish can be difficult to apply and it takes a very long time to dry. Because of this, airborne shop dust becomes a real problem. It settles in the finish before the finish is dry. Then it has to be rubbed out before another coat is applied.
For the beginner, an oil finish is the best choice. It's easy to apply, dries fairly quickly and is not difficult to repair. It also imparts silkiness to the surface and develops a beautiful patina over time.
To pick a suitable finish, you'll have to shop through a multitude of products with varying characteristics. The most common finishes are shellac, lacquer, varnish and oil. These are all solvent or oil-based products, so make sure to take precautions. Wear protective gloves, goggles and a respirator with organic vapor cartridges when using these materials. Most importantly, make sure your work area is ventilated according to the recommendations printed on the produc's container.
One of the biggest differences among the four traditional finishes is how they function on wood. Shellac, lacquer and varnish are all surface finishes. This means that they do not penetrate, to any great extent, past the surface of the wood. The first coat goes in the farthest, but subsequent coats merely build on the first to form a smooth, usually glossy, surface. Oil, on the other hand, is considered a penetrating finish because it reaches much deeper into the wood and leaves only a microscopic layer of finish on the surface. Subsequent coats continue to penetrate.
All these finishes have their strengths and weaknesses. Shellac, for instance, when properly applied, creates a stunning high-gloss surface, which, over time, takes on a remarkable amber color. It's also very fast-drying, which is a great advantage over some other finishes. Unfortunately, shellac is very prone to water stains.
Lacquer is also quick-drying and is the preferred finish of many professionals. It's usually sprayed on and yields a clear, hard finish that stands up well to practically any abuse. It is, however, very flammable.
Varnishes, both the traditional types and the newer poly-urethane versions, are extremely durable and some impart a warm amber tone, not unlike shellac. Unfortunately, varnish can be difficult to apply and it takes a very long time to dry. Because of this, airborne shop dust becomes a real problem. It settles in the finish before the finish is dry. Then it has to be rubbed out before another coat is applied.
For the beginner, an oil finish is the best choice. It's easy to apply, dries fairly quickly and is not difficult to repair. It also imparts silkiness to the surface and develops a beautiful patina over time.
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Step 1: Surface Prep
Proper surface preparation is key to good finishing. This requires a bit of sanding. For the best results, you should work through a sequence of abrasives, starting at 120-grit and moving to 150, then to 180 and 220-grit, finishing up with 320-grit. Ease all the edges on your project with sandpaper and a sanding block. Work across the grain for best results. Always dust off the piece thoroughly before moving to the next grit and ease any sharp edges by hand sanding.
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Step 2: Rub With Oil
When you're done sanding the entire piece, brush off all the dust with a tack cloth or a rag that's been slightly dampened with linseed oil. Rub the oil into the wood and let it dry for 1 hour. Then wipe off any excess.
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Step 3: Test the Finish
Once youve chosen your coloring method, be sure to test it out on some scrap pieces of stock before turning to your project. Taking the time to get it right is much easier than removing a stain or dye that you dont like. When youre ready to apply your oil finish, begin by rubbing a liberal amount of oil into the surface of the wood using a lint-free rag. Use No. 0000 steel wool to rub the finish between coats. Use a tack cloth to remove all the dust before recoating.
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Step 4: Let It Dry and Rub With Steel Wool
Allow the oil to absorb for about an hour, then wipe off the excess. Let the surface dry for 24 hours, and then rub the whole piece with No. 0000 steel wool.
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Step 5: Wax It
Once the last oil coat is dry, apply a light coat of paste wax to your project. Be sure to cover all the surfaces.
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Step 6: Buff It
Let the wax dry until the surface it takes on a dull appearance. Then buff the entire piece to a high luster with a clean, dry cloth.