Basics of Wood Finishing

Whether you're planning to build, refinish furniture or bookshelves for your room, make gifts, or take up woodworking as a profession, you'll find woodworking to be a rewarding experience and even a money saver, particularly important during these challenging economic times.

Today, the secret of a fine wood finish is no secret at all. Beautiful results can be obtained easily if you prepare the wood surface to accept a finish to minimize problems during the finishing process.

How do you know what type of wood to use?

Before making your purchase, think about how you intend to use the wood. When choosing the actual piece of wood, check for any twists or warping. Look for splits at the ends of the board and surface defects like knots. Look for machine marks, insect holes, dents, and shipping scars. Will these defects affect how you intend to use the wood? Compare the different types of grain patterns. Try to match grain patterns in boards that will be used next to one another, since differences will become more pronounced once you brush on a coat of stain. Finally, once you've made your decision, be sure to measure the wood before you buy it.

Getting Started

Before starting almost any wood finishing project, you should have these items on hand: heavy plastic drop cloths and newspapers, rags, brushes or other applicators, #120 and #220 sandpaper, paper towels, cotton swabs, mineral spirits and sealed metal containers, such as empty paint cans (for cleaning brushes, and, with the addition of water, for disposing of rags and waste soaked with oil finishes). Rubber gloves are recommended for keeping your hands clean. Old clothes are recommended because they are usually expendable and generally lint-free.

For best results and safety, remember to follow carefully all label directions and cautions.

Choosing the Proper Applicator

Stains may be applied with clean rags, cheesecloth, brushes, and other applicators. For best results when using a brush, we recommend the use of a high quality brush. Why?

• It carries more finish, meaning fewer trips to the can
• Your work will be neater, with fewer runs and drips
• It won't leave bristles in your finish
• It won't leave "holidays" or lap marks
• It responds better to cleaning and storage
• It springs back to life the next time you reach for it
• It will last longer

What are the characteristics of a high-quality brush?

• Long, silky, flexible bristles of varying lengths
• Bristles with "flagged" or split tips
• A non-corrosive metal or plastic ferrule
• Contoured wooden handle
• Tapered, well-secured bristles
• Well-balanced feel

Use natural bristle brushes only if working with oil-based products. Both polyester bristles (medium to high-quality brushes) and nylon bristles (low to medium-quality brushes) can be used for either oil or water-based finishes. Note, nylon bristles are not recommended for shellac or two-part epoxy finishes. Finally, disposable foam poly brushes are best suited for applying stain to small projects and hard-to-reach areas, like those between chair spindles, since they provide better control.

Wood Preparation

One of the most important steps in wood finishing is sanding. A thorough sanding is often the factor that separates "acceptable" results from "professional-looking" results. Start with a medium grade of sandpaper (e.g. #120) and gradually work your way to a finer grade (e.g. #220). Sand in the direction of the grain for a smooth, uniform finish and remove all sanding dust, using a vacuum, dry paint brush or cloth, before finishing. Look out for dried glue, especially in the joint area. If it's not thoroughly removed by sanding, it will interfere with the staining process. End-grains (areas where the wood has been cut against the grain), such as the front side of a table, tend to soak up more stain than surfaces cut with the grain. With additional sanding to end-grain areas, you can better control the absorption of stain.

Choosing a Color

Color is determined by four factors: The color of the stain selected; the nature of the wood and how porous it is; how long the stain is left on, from a few seconds to a maximum of 15 minutes; and the extent of wiping when removing excess stain. Choose from the many wood tone colors, using a dealer's sample board or manufacturer's color cards. But remember: Different species of wood absorb stain differently. Test the color on a hidden section of the wood you are using.

TRY THESE TIPS FOR BEST RESULTS

To sand between chair spindles, wrap a strip of sandpaper around the spindle and work it back and forth like dental floss. For bigger jobs, use a power sander, but first practice on a spare piece of wood. To check your work, run a sock over the sanded wood. If it snags, you'll need to resand the area.

To help prevent wood swelling and warping due to changes in temperature and moisture, finish all exposed surfaces of the wood item with stain and finish. This includes areas not easily visible, like the insides of cabinets and drawers and the undersides of tables..

When applying additional coats of a protective finish, the bottom coat must be dry before recoating. It is also important to sand between coats to improve coat-to-coat adhesion, and to remove all sanding dust before recoating. Failure to follow these steps may result in adhesion problems.

If you have product left over, wipe the can rim so that the product doesn't dry out and so that rust doesn't form on the can. This will also help you seal the can properly. After sealing, store cans away from heat.

Clean brushes soiled with oil-based finishes using mineral spirits; soap and water are all that is needed for brushes used with water-based products.

Safely dispose of used rags and other waste. Rags, steel wool and other waste soaked with oil finishes may spontaneously catch fire if improperly discarded. Place rags, steel wool and waste immediately after use in a water-filled metal container. Tightly seal and then dispose of in accordance with local regulations. Be sure to keep the container out of reach of children.

Excerpt from www.minwax.com.

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