How to Get Wooden Furniture Ready for Refinishing

Refinishing furniture isn't merely about removing an old coat and applying a new one; it also involves prepping the exposed wood. This preparation requires both patience and effort, but it’s crucial for a successful refinishing project. A flawless finish depends on proper preparation. In this guide, we’ll cover the three key stages of getting wood furniture ready: sanding, bleaching, and sealing. Let's start with the first step commonly tackled in home improvement projects: sanding.

Sanding Method

Sanding, more than any other refinishing task, demands time and attention. It should always be done manually; power tools can harm the wood. It requires careful, thorough work, consistently following the grain. Although it’s time-consuming, sanding is mostly about patience. The effort you invest in this step will directly affect the final finish. Before you start, ensure you’re familiar with the fundamentals.

The first rule of sanding is to always work with the wood grain. Sanding against the grain can create noticeable and permanent scratches. The second important rule is to always use a sanding block, as it helps maintain consistent pressure while sanding.

For flat surfaces, ensure the sanding block is padded. An unpadded block lacks flexibility, and trapped grit under the sandpaper can scratch the wood. For curved surfaces, opt for a thick foam pad or sponge wrapped with sandpaper. The padding will mold to the curves, applying even, firm pressure.

Mastering good sanding technique is straightforward. With a sanding block, use long, light, even strokes along the wood grain. Avoid pressing too hard, as excessive pressure can cause gouging at the edges of the sanding block. Replace the sandpaper whenever it becomes clogged or worn smooth.

To achieve a smooth and uniform surface, progress through increasingly finer sandpaper grades. Any roughness from the initial sanding will be eliminated with each subsequent sanding. Start with coarse-grit paper—grade 3/0 for most woods, or grade 4/0 for softwoods like pine or poplar. Gradually work your way up to grades 4/0, 5/0, and finally 6/0. Although finer grit can theoretically result in a smoother finish, using excessively fine paper may clog the wood and disrupt the finishing process.

Sand the entire piece with each grade of sandpaper before moving to the next. After each sanding, be sure to brush off or vacuum the dust, and clean the wood with a tack cloth. Dust or debris trapped under the paper can scratch the surface. For tight corners that are hard to reach with sandpaper, use a sharp scraper to gently smooth the wood in those areas. However, be cautious with scrapers, as they can leave marks, and should only be used when sanding is not feasible.

Rungs, Rounds, and Spindles

Narrow rungs, spindles, legs, and other rounded elements require extra care. Heavy sanding with coarse-grit paper, whether or not using a block, can flatten or distort these round parts; only minimal wood should be removed. To sand round features, cut narrow strips of fine-grit sandpaper—grades 5/0 and 6/0—avoiding coarser grades altogether.

Wrap a strip of sandpaper around the rounded part, moving it back and forth across the surface to sand. Adjust your sanding angle as you go to ensure an even smoothness. Be cautious not to leave visible horizontal grooves along the edges of the sandpaper strips.

Carvings

Carvings, particularly shallow ones, need extra care. Coarse sanding can blur the details of the carving, so only use fine-grit sandpaper, such as grades 5/0 and 6/0, to smooth the stripped wood, and avoid using a sanding block. Sand lightly along the grain, pressing the paper into the carved areas with your fingertips. Work as deep into the carving as you can, but take care not to flatten the rounded surfaces.

Crevices and Curved Edges

For crevices, fold a strip of sandpaper to fit the angle and sand along the crevice. Use slow, controlled strokes, ensuring even pressure throughout.

Ensure the sandpaper stays in place. If you're not careful, you may damage the edges of the wood around the crevice. Sand convex curves carefully, following the curve’s shape, and apply gentle pressure with your fingers. Be cautious not to damage adjacent surfaces or edges. For concave curves, use a dowel of the same diameter as the curve. Wrap sandpaper around the dowel and gently move it back and forth along the curve. Be extra careful around the ends of the curve to avoid hitting nearby surfaces.

Veneers and Fine Patinas

When working on veneered furniture, extra caution is needed. Standard sanding techniques could easily damage the wood. The same applies to wood with a fine patina, as regular sanding will strip away the patina. For optimal results, veneered pieces and those with a delicate patina should be smoothed with the utmost care.

For sturdy whole-surface veneers, use fine-grit sandpaper in grades 5/0 and 6/0. Avoid coarser grades. For very thin veneers or wood with a patina, it’s best to use steel wool for smoothing. The technique remains similar to sanding, but patience is key.

If the surface is rough, begin with No. 0 steel wool and gradually progress to Nos. 00 and 000 for the final smoothing. If the surface is already smooth, stick to the finer grades of steel wool. Between each grade, remember to brush off or vacuum any dust and steel wool debris, then wipe the wood clean using a tack cloth.

Raising the Grain

When wood absorbs moisture, the cells that form the grain expand, causing the grain to rise above the wood’s surface. Any form of liquid will trigger this reaction, even if the wood has been sanded smooth. The finish itself can also raise the grain. To avoid raised grain appearing in the final piece, intentionally raise the grain and then sand it down before applying the finish after the final sanding.

The simplest method to raise the grain is with water. Sponge the sanded piece of furniture with cold water, ensuring the wood is evenly and thoroughly soaked; then wipe off any excess. It’s important to make sure the wood is uniformly wet, with no dry areas or puddles, to avoid water stains as it dries. Be particularly cautious not to overwet veneers, as the glue holding them together may be water-soluble.

Allow the wood to dry completely. Once it’s dry, the fibers of the grain will stand stiffly above the surface. Use grade 5/0 or 6/0 sandpaper to gently smooth these raised fibers down to the wood’s surface; for delicate surfaces, No. 000 steel wool is recommended. Take care not to roughen the surface. Afterward, brush off or vacuum the sanding debris and wipe the wood clean with a tack cloth.

After sanding your furniture, you might notice some unsightly stains or discolorations. You may need to bleach the wood before refinishing it. Fortunately, detailed instructions are available in the following section.

How to Bleach Wood Furniture

Bleaching is typically a first-aid solution, not a regular step in refinishing. It is used when the surface shows stains, black rings, water spots, discoloration, or blotchiness; when the color is uneven, or when remnants of old stains or fillers remain after removing the finish. Oak, walnut, and mahogany are particularly prone to old filler issues. Bleaching can also help balance the color of furniture made from multiple woods, lightening the darker woods to match the lighter ones.

Before applying bleach to any furniture, ensure that the wood is suitable for bleaching. Some woods, like cherry and satinwood, should never be bleached. Others, like bass, cedar, chestnut, elm, redwood, and rosewood, are challenging to bleach. Woods like pine and poplar are so light that bleaching can make them appear dull. Birch, maple, and walnut can be bleached, though it will alter their unique color. Rare woods such as mahogany and teak generally don't benefit from bleaching. Common woods like ash, beech, gum, and oak, however, are easy to bleach and often benefit from it.

Choosing the right bleach depends on the problem you're addressing. Different issues may require either a strong bleaching agent or a milder one. Here are some common bleach options you might consider.

Not all bleaching tasks require the same type of bleach. Depending on the issue you're trying to fix, you may need a powerful bleaching agent or a more gentle solution. Below are some commonly used bleach options to consider.

Laundry Bleach: A mild solution that addresses most color issues in refinishing, such as stains, unremoved fillers, ink marks, and water spots. It works well for evening out blotchy areas and for slightly lightening the wood, but it won't dramatically alter the wood's color. Before opting for stronger bleaching agents, try laundry bleach—it often provides the solution.

Oxalic Acid: Available in powder or crystal form, oxalic acid is used to eliminate black water stains from wood and to restore chemically darkened wood to its natural shade. This issue typically arises only in pieces that have been commercially stripped, as lye and ammonia—substances that discolor wood—are not recommended for non-professional use. Oxalic acid should be applied to the entire surface since it also bleaches out old stains. Often, bleaching the entire piece is necessary to achieve an even color. It works better on open-grained wood than on close-grained varieties.

Two-Part Bleaches: These commercial wood bleaches are highly effective for lightening or completely removing the natural color of wood. If you need to lighten a dark piece of furniture to match a lighter décor, this is the bleach to use. However, two-part bleach is potent and must be handled carefully—rubber gloves and safety goggles are essential. It is also relatively expensive. Several brands are available.

Bleaching Techniques

Regardless of the bleach used, remember that the results are permanent. While you may be able to restain the wood if it becomes too light, uneven bleaching is extremely difficult to correct. Ensure that the wood is thoroughly clean, and minimize handling. The bleach must be applied evenly for optimal results.

Before using bleach, it's essential to test it on a piece of scrap wood from the same type or on a hidden area of the furniture. Be sure you understand how the bleach reacts and how quickly it works. Generally, bleaches act faster on softwoods and slower on hardwoods.

Bleaching is not particularly difficult, but it does require caution as bleaches are potent chemicals. Stronger bleaches can cause harm to your skin, eyes, and respiratory system. Always wear rubber gloves and safety goggles when working with bleach, and ensure your workspace is properly ventilated. Follow the manufacturer's instructions carefully, and wash off any bleach from your skin immediately.

Proper bleaching also demands careful application and removal. Always use a synthetic-bristle brush since natural bristles will be damaged by the chemicals. Apply the bleach along the wood's grain, ensuring the surface is evenly wet, with no dry patches or puddles. Allow the bleach to work as described in the following steps.

After bleaching, clean the wood with a damp cloth. To remove any bleach residue, neutralize the wood properly: use ammonia for oxalic acid, borax for laundry bleach, or two-part bleaches. Thoroughly wash the bleached wood with the chosen neutralizer, avoiding over-wetting it. Then, rinse the wood with clean water and dry it with a soft cloth. Let the furniture piece dry for at least two days before proceeding with any additional work.

Laundry Bleach

Apply full-strength laundry bleach, brushing it evenly across the entire surface. For spot treatment or lightening discolored patches, apply bleach directly to those areas. Laundry bleach works rapidly, and within a minute or two, you should notice the stain fading. If you're removing an old stain, wipe off the bleach with a damp cloth once the stain has lightened.

For spot bleaching to remove stains or blend areas, wait until the bleached spots match the surrounding wood's color. Then, apply bleach across the whole surface. Once the color is uniform, wipe the bleach away with a damp cloth. Lastly, neutralize the treated wood using a solution of 1 cup borax in 1 quart of hot water. Rinse with clean water and dry thoroughly.

Oxalic Acid

Oxalic acid is not caustic but can be poisonous. Always wear rubber gloves and safety goggles, and ensure adequate ventilation. To make the acid, dissolve 1 ounce of powder or crystals into 1 cup of warm water, creating a saturated solution. Prepare enough bleach to cover the entire surface or piece of furniture.

Apply the acid solution evenly across the wood, brushing it along the grain to cover the entire surface. On softwoods, the results will appear quickly, while hardwoods take longer. Let the acid sit for around 20 minutes before wiping it off with a damp cloth. If the bleaching is not even, reapply the acid as needed. For hardwoods, the process may take up to an hour. Afterward, wipe the wood clean, rinse it with water, and neutralize it with a solution of 1 cup household ammonia and 2 quarts of water. Rinse again, then dry thoroughly.

Two-Part Bleaches

Two-part bleach is user-friendly and typically works swiftly. The bleach comes in two components, usually marked as '1' and '2' or 'A' and 'B', which are applied separately. Always follow the manufacturer's instructions precisely. The first solution is generally left to work for around 20 minutes before applying the second solution.

Carefully follow the instructions, applying the first solution and letting it sit before adding the second. One application typically lightens the wood enough, but if it's still too dark, apply the treatment again. After bleaching, wipe the wood with a damp cloth and neutralize it using a solution of 1 cup of borax in 1 quart of hot water. Rinse the wood with clean water and dry it completely.

Post-Bleach Treatment

Using any bleach will raise the wood grain, even if the furniture has already been sanded. To prevent the raised grain from interfering with the finish, you must resand the surface to restore it to the original level once the wood is dry.

Once the bleaching process is complete, allow the piece of furniture to dry for at least two days. Afterward, lightly sand the wood grain using 5/0 or 6/0 sandpaper, taking care not to damage the surface. Since there may still be traces of chemicals in the wood, wear a breathing mask and use a vacuum to remove any dust generated by sanding. Finish by wiping the wood down with a tack cloth to remove any remaining particles.

Another issue with bleaching, especially when using laundry bleach, is the potential for the wood to take on a whitish or grayish appearance. This is not a major concern; it simply indicates that the bleach has dried out the surface fibers. On hardwoods, this effect will disappear once the finish is applied. On softwoods, however, the grayish tint may be more noticeable, and the fibers may appear loose. To remedy this, gently rub the wood along the grain with No. 000 steel wool, ensuring the color is even. The grayish hue will vanish entirely once the finish is applied.

While bleaching is a cosmetic process, it can produce surprisingly effective results when applied at the right moment.