Refinishing hardwood floors


Floor DIY How-To Articles

There has been a revival of interest in older homes. Many people are spending their weekends replacing molding, stripping floors, insulting walls, refinishing woodwork, and revitalizing the works of past craftsmen. Others are remodeling older homes for economy and function and finding that the old ways are often the best.

In this final section, you’ll learn how to refinish a hardwood floor. In most cases, it can be done easily by the average do-it-yourselfer with an understanding of the process and some rented equipment. Take your time. Learn how it’s done. Talk with your supplier and to others who have refinished hardwood floors. You’ll find a wealth of information and opinions on how best to renew hardwood flooring.

If you haven’t already read Section 4 on how to finish hardwood floors. It discusses the types of finishes that are commonly used, the equipment needed, how the finishes are applied, and other background information that is vital to the flooring restorer. It also includes numerous photos of how an old hardwood floor was restored.


Where floors have become badly discolored and worn by neglect or improper maintenance, the most practical procedure, and often the only one that will restore a fine finish, is to have the old finish removed and the floor reconditioned by power sanding (FIG. 6-1). Where the floors have been reasonably well-maintained but the finish has become dingy with age, refinishing without power sanding may be practical. The method for removing the old finish depends upon the kind of finish that was originally used.


Fig. 6-1: An electric floor sander can be rented to refinish an old hardwood floor.

Old, discolored varnish is usually removed most easily by power sanding. If desired, this can be done with a liquid varnish remover. Alkaline solutions in water and removers sold in powder form that are dissolved in water should not be used.

Follow the directions for the liquid remover carefully. Since some of the old, discolored varnish remains embedded in the wood, do not expect a complete restoration of the natural wood. Clean traffic channels where the old varnish has worn through and where dirt has been ground into the wood thoroughly by sanding.


Old shellac and wax finishes that have merely become soiled by dirt that has lodged in the wax coating may be cleaned by going over the floor with steel wool that has been saturated with clean turpentine. Any white spots in the shellac that have been caused by contact with water may be taken out by rubbing the spot lightly with a soft cloth that has been moistened with denatured alcohol. The alcohol must be used with care, how ever, to avoid cutting the shellac coating.

On floors where the dirt is ground into the shellac itself or where white spots have penetrated the coating, more drastic treatment is necessary. First, wash the floor with a neutral or mildly alkaline soap solution. Then scour the floor with No. 3 steel wool and denatured alcohol. If the floor boards are level and are not warped or cupped, the scouring can be done to advantage with a floor polishing machine that is fitted with a wire brush to which a pad of the No. 3 steel wool is attached. After scouring, the floor should be wiped clean and allowed to dry thoroughly before you refinish it with shellac or another finish.


Some older floors have been finished with linseed oil. To refinish, clean the surface and apply a new coating of oil. Make needed repairs and smooth rough spots if the floor is in poor condition.

To remove oil, some professionals recommend that you wet about 10 square feet of floor with a mop and warm water and then liberally sprinkle the area with a mixture of one part soap powder and three parts trisodium phosphate. Scrub the floor with a stiff brush. Use only as much water as needed to form an emulsion, which will float the oil to the surface. As the oil is loosened, remove it with a squeegee and mop. Rinse the area and mop it dry Treat the other sections in the same way. When the entire floor has been cleaned, let the surface dry at least 24 hours and then sand it with a machine and finish it as desired.

A reminder Many professional floor refinishers recommend that no water touch the wood since it is quickly absorbed and may cause the wood to crack and swell once the finish is installed. Discuss this with your floor supplier.


Those are some of the ways that you can refinish your hardwood floor with little or no need for a floor sander. In many cases, however, it is best to roll up your sleeves and plan on renting a floor sander for a day or two in order to completely strip an old floor. TABLE 6-1 suggests the selection of sandpaper you should buy when refinishing an old floor.

First, remove all the furniture, rugs, and draperies from the room. If you’re planning on painting or applying a wall-covering, do that work before you refinish the floor so the paint or paste won’t drip on the new floor. Vacuum the floor.

Look for protruding nail heads and drive them down with a nail set. Tighten any loose boards by face-nailing them, preferably into joists, and then countersinking them with a nail set.

Table 6-1: Sanding Old Floors


Covered with varnish, shellac, paint, etc.


First Cut

Second Cut



Type of Paper


3 1/2 (20)

Medium 1 (40)

Fine 2/0 (100)

Fig. 6-2: Before sanding an old floor, remove the base shoe (courtesy National Oak Flooring Manufacturers Association).

Before sanding an old floor, remove the base shoe (FIG. 6-2). Use a wood wedge behind the pry bar to protect the baseboard from damage. Figure 6-3 illustrates the cross section of a typical hardwood block floor.


Fig. 6-3: Checking the thickness of the flooring

Most oak and many other types of flooring can be sanded and refinished a number of times. Thinner floors should be refinished with caution because repeated sanding could wear through to the subfloor. To deter mine the floor thickness, remove a floor heating register or the shoe mold and baseboard (FIG. 6-3) so that an edge of the flooring is exposed and can be measured.

When you are refinishing thinner floors — or ½ or 3/8 inch — use the floor polishing machine and screen abrasive rather than the drum sander. Remove as little of the surface as possible. Do not do this for face-nailed 5/16 square-edged, or 5/16-inch square-edged flooring that has been installed in mastic, however. The 5/16-inch type is almost always face- nailed; others are blind-nailed through the tongue. The nails must be set, or driven deeper into the wood, to permit sanding of the floor.

The following instructions apply to standard 3/4-inch strip, plank, and block floors and, with the cautions just mentioned, to the thinner materials. Use an open-faced paper to remove the finish. The heat and abrasion of the sanding operation make the old finish gummy and will quickly clog normal sandpaper. When you get down to the new wood, you can switch to a regular paper for the final finishing cuts.

The number of cuts that are required for the refinishing operation will be determined by the condition of the old floor and the thickness of the finish being removed. If the surface is in good shape and has no thick build-up of old finish and wax, one pass with the disc sander and an extra- fine sandpaper may be sufficient. Just be sure you’ve removed all the old finish.

If the floor is badly scarred or the boards are cupped or dished, use as many cuts as necessary to get a smooth, unblemished surface. Make the first one or two cuts at a 45-degree angle with a medium-grit sandpaper. Follow the instructions given in Section 4 for sanding a new floor on the succeeding cuts.


As you learned in Section 4, there are two basic finishes that can be applied to hardwood floors: penetrating sealers and surface finishes. Most manufacturers of penetrating sealer finishes also make a renovator or reconditioning product you can use when traffic or other conditions cause a discoloration or wear of the finish. These products restore the floor to its original appearance without the need for sanding. They can be used on most prefinished flooring, which may be identified by the beveled edge on each strip or block.

Another way to determine if a floor was originally finished with a penetrating sealer is to scratch the surface in a corner or some other inconspicuous space with a coin or other sharp-edged object. If the finish does not flake off, a penetrating sealer was probably used and a renovator product can be applied to restore it to its original beauty

If the condition of the flooring is very bad, sanding and the application of a complete new finish may be needed. Once the floor is completely stripped and cleaned, follow the directions in Section 4 for finishing hardwood floors.

With most surface finishes, the recommended method of restoration is to sand off the old finish and apply a completely new finish of a penetrating sealer or polyurethane. If the floor was originally finished with polyurethane and is in good condition, it should be cleaned and screen-disced to rough up the old finish.

Caution The adhesion of polyurethanes, epoxies, and ureaformaldehyde finishes is affected by wax and grease, as well as some types of stains, bleaches, or sealers. Further more, one type of polyurethane may not be compatible with another type. TABLE 6-2 offers information on the grain of various types of wood and notes on finishes that may guide you in refinishing your old hardwood floor.


Sometimes you will run across a strip or block of hardwood flooring that needs to be planed before it can be refinished. Let’s consider how this is done.

The plane is the most extensively used hand shaving tool. The large family of planes includes bench planes and block planes, which are designed for general surface smoothing and squaring, and other planes that are designed for special types of surface work.

Table 6-2 Wood and Wood Finishes

The principal parts of a bench plane and the manner in which it is assembled are shown in FIG. 6-4. The part at the rear that you grasp to push the plane ahead is called the handle. The part at the front that you grasp to guide the plane along its course is called the knob. The main body of the plane, which consists of the bottom, the sides, and the sloping part that carries the plane iron, is called the frame. The bottom of the frame is called the sole and the opening in the sole, through which the blade emerges, is called the mouth. The front end of the sole is called the toe, and the rear end is the heel.

Fig. 6-4 Components of a typical bench plane.

Fig. 6-5 jointer or fore plane.

Fig. 6-6 Jack plane.

There are three types of bench planes: the jointer plane or fore plane (FIG. 6-5), the jack plane (FIG. 6-6), and the smooth plane (FIG. 6-7). All are used primarily for shaving and smoothing with the grain; the chief difference is the length of the sole. The sole of the smooth plane is about 9 inches long; the sole of the jack plane about 14 inches long; the sole of the jointer plane from 20 to 24 inches long. The longer the sole of the plane, the more uniformly flat and true the planed surface will be. Consequently the bench plane you should use depends on the requirements with regard to surface trueness.

Fig. 6-7 Smoothing plane.

Fig. 6-8 Block plane.

The smooth plane is, in general, a smoother only. It will plane a smooth, but not an especially true, surface in a short time. It is also used for cross-grain smoothing and the squaring of end stock, It is especially useful for planing smaller wood strip flooring.

The jack plane is the jack-of-all-work of the bench plane group. It can take a deeper cut and plane a truer surface than the smooth plane. It is most often used to plane larger strip or block wood flooring, that is either on or off the floor.

The jointer plane is used when the planed surface must meet the

highest requirements with regard to trueness. A jointer plane would be used on the floor-level adjoining hardwood strips or blocks.

A block plane and the names of its parts are shown in FIG. 6-8 Note that the plane iron in a block plane doesn’t have a plane iron cap. Also, unlike the iron in a bench plane, the iron in a block plane goes in bevel- up. The block plane, which is usually held at an angle to the work, is used chiefly for the cross-grain squaring of end stock. It is also useful for smoothing all planed surfaces on very small work.

Another shaving tool that you may be able to use to smooth a hard wood flooring strip or block is the jointer (FIG. 6-9). The jointer is a machine for power-planing the faces, edges, and ends of stock. The planing is done by a revolving cutter-head that is equipped with two or more knives. The table consists of two parts on either side of the cutter-head. The stock is started on the infeed table and fed past the cutterhead and onto the outfeed table. The surface of the outfeed table must be exactly level with the highest point reached by the knife edges. The surface of the infeed table is depressed below the surface of the outfeed table by an amount equal to the desired depth of the cut. A jointer could be used to shave the surface off new hardwood boards that replace old ones or to lower the depth of all hardwood floor boards in a room prior to installation.

Fig. 6-9 Jointer operation: Depth of cut = distance the infeed table is depressed below the highest point reached by the knife edges. Outfeed table; Infeed table


As you refinish a hardwood floor or remodel to accommodate new heat ing vents, new walls, piping, or cabinets, you may need to change the shape of the hardwood floor that is to be repaired or installed. The com mon wood chisel is extremely useful for this task.

A wood chisel should always be held with the flat side, or back side, against the wood for smoothing and finishing cuts. Whenever possible, it should not be pushed straight through an opening, but should be moved laterally at the same time that it is pushed forward. This method ensures a shearing cut, which with care will produce a smooth and even surface, even when the work is across the grain. On rough work, use a hammer or mallet to drive the socket-type chisel.

On fine work, use your hand as the driving power on tang-type chisels. For rough cuts, the bevel edge of the chisel is held against the work. Whenever possible, other tools, such as saws and planes, should be used to remove as much of the waste as possible. The chisel should be used for finishing purposes only.

To chisel horizontally with the grain, grasp the chisel handle in one hand and extend your thumb towards the blade (FIG. 6-10). The cut is con trolled by holding the blade firmly with the other hand, knuckles up, and with your hand well back of the cutting edge. The hand on the chisel han dle is used to force the chisel into the wood. The other hand that presses downward on the chisel blade regulates the length and depth of the cut.

Fig. 6-10: Chiseling horizontally with and across the grain. Bevel side down for roughing cut; Thumb and fingers of left hand guide cutting edge and act as brake; Left hand guides cutting; Bevel side up for smoothing cut; To avoid splintering corners when chiseling across grain cut halfway from each edge toward center

To chisel horizontally across the grain, hold the work so that it does not move. Remove most of the waste wood by using the chisel with the bevel down. For light work, use hand pressure or light blows on the end of the chisel handle with the palm of your right hand. For heavy work, use a mallet. To avoid splitting at the edge of the wood, cut from each edge to the center and slightly upward so that the waste wood at the cen ter is removed last (FIG. 6-10).

Make finishing cuts with the flat side of the chisel down. Never use a mallet when making finishing cuts, even on large work. One-hand pres sure is all that is necessary to drive the chisel, which is guided by the thumb and forefinger of your other hand. Finish cuts should also be made from each edge toward the center. Do not cut all the way across from one edge to the other, or the far edge may split.

To cut a round corner on the end of a piece of hardwood flooring, first lay out the work and remove as much waste as possible with a saw (FIG. 6-11). Use the chisel with the bevel side down to make a series of straight cuts tangent to the curve. Move the chisel sideways across the work as it is moved forward. Finish the curve by paring with the level side up. Convex curves are cut in the same manner as round corners.

When cutting a concave curve with a chisel, remove most of the waste wood with a coping saw or a compass saw. Smooth and finish the curve by chiseling (FIG. 6-11) with the grain. Hold the chisel against the work. Press down on the chisel with the other hand and, at the same time, draw back on the handle to drive the cutting edge in a sweeping curve. Care must be used to take only light cuts, or the work may be damaged.

Fig. 6-11 Chiseling corners and curves on hardwood flooring.

Fig. 6-12 Vertical chiseling on hardwood flooring.

Vertical chiseling (FIG. 6-12) means to cut at right angles to the surface of the wood, which is horizontal. This technique is used to make a hole in a hardwood flooring strip or block to allow for the passage of a cable, pipe, or other element. Usually it involves cutting across the wood fiber when you are chiseling vertically across the grain, using a mallet to drive the chisel.

To keep you safe when you use a chisel, here are a few reminders:

• Secure the work so that it cannot move.

• Keep both hands back of the cutting edge at all times.

• Don’t start a cut on a guideline. Start slightly away from the line so that there is a small amount of material to be removed by the refinishing cuts.

• When starting a cut, always chisel away from the guideline and toward the waste wood so that no splitting will occur at the edge.

• Never cut towards yourself with a chisel.

• Make the shavings thin, especially when finishing.

• Examine the grain of the wood to see which way it runs. Cut with the grain to sever the fibers and leave the wood smooth. Cutting against the grain splits the wood and leaves it rough. This type of cut cannot be controlled.

Safe and proper chiseling and planing techniques will help you do a more professional job when you refinish your hardwood floor. That’s it! You’ve learned to understand, plan, install, finish, maintain, and refinish hardwood floors. Now it’s time to sit back and enjoy.

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Friday, 2010-11-26 13:30