Refinishing wood floors restores their natural beauty and extends their service life. This process involves removing the old, worn finish and applying a new protective layer, which enhances the aesthetic appeal and durability of the flooring. A successful outcome depends on meticulous preparation, a systematic sanding approach, and the correct application of the final protective coating. This guide details the necessary steps to achieve a professional-grade floor finish.
Essential Preparation and Structural Repair
Thorough preparation is essential before sanding begins. Completely empty the room, removing all furniture, rugs, and wall hangings that could be damaged by dust or interfere with the work area. Carefully remove baseboards and shoe molding to allow the edge sander full access to the perimeter of the floor.
Structural integrity must be addressed next to prevent damage to the sanding equipment and ensure a flat surface. Secure all loose floorboards by driving screws into the joists to eliminate movement and squeaks. Check for and drive down all protruding nails or screws using a nail set, ensuring the heads are countersunk at least an eighth of an inch below the wood surface. A single exposed metal fastener can tear a sanding belt or damage the drum of the rental machine.
After structural repairs, the room must be sealed to contain the fine wood dust that the sanding process generates. Use plastic sheeting and painter’s tape to cover doorways, windows, and any heating, ventilation, and air conditioning (HVAC) vents. Minor gaps and small holes in the floor can be filled with a wood filler product that closely matches the color of the wood species.
The Multi-Stage Sanding Process
Sanding is the most physically demanding part of the process, requiring the use of specialized equipment like a drum sander and an edge sander. The goal is to systematically remove the old finish and progressively smooth the wood surface by moving through a sequence of increasingly finer sandpaper grits. Skipping a grit will leave deep scratches from the previous, coarser paper that the next grit cannot fully remove.
The process begins with a coarse grit, usually 36 or 40, which is aggressive enough to strip the old finish, adhesive residue, and deep imperfections. The drum sander must be kept moving at all times, lowered onto the floor only when the machine is running at full speed and lifted before stopping to prevent gouging the wood. Passes should be made with the grain of the wood, overlapping each pass by about one-third of the drum’s width to ensure uniform material removal.
Once the entire floor is sanded with the coarse grit, the perimeter and corners are addressed using the edge sander with the same grit paper. Before moving to the next stage, the floor must be thoroughly vacuumed to remove all dust and abrasive particles. The next pass uses a medium grit, such as 60 or 80, which removes the scratch pattern left by the initial coarse paper.
The final sanding pass uses a fine grit, typically 100 or 120, which polishes the wood and prepares it for the finish application. After each grit change, the floor must be meticulously cleaned with a vacuum and then wiped down with a tack cloth. Residual dust from a coarser paper can be dragged across the floor during the next pass, creating visible scratches in the final finish.
Choosing and Applying the Protective Finish
After the final sanding and cleaning, the floor is ready for the protective finish, which involves both aesthetic and durability choices. If a color change is desired, staining is optional and must be tested on a scrap piece of the sanded floor to confirm the final appearance. Stain is typically applied with a rag or foam applicator, allowed to penetrate the wood for a short time, and then the excess is wiped off to prevent a blotchy appearance.
The protective coating itself is generally one of three types: water-based polyurethane, oil-based polyurethane, or hard wax oil. Water-based polyurethane is popular for its low volatile organic compound (VOC) content, fast drying time, and clear finish that does not yellow the wood. Oil-based polyurethane is known for its durability and resistance to abrasion, but it imparts an amber tint that deepens over time and requires a much longer drying and curing period due to its solvent content.
Hard wax oils offer a more natural, matte appearance by penetrating the wood fibers rather than forming a plastic-like film on the surface. While they may require more frequent maintenance, hard wax oils are highly repairable, allowing for spot touch-ups without sanding the entire floor. Finish sheen levels range from Matte, which hides imperfections well, to High-Gloss, which provides a mirror-like, highly reflective surface.
The finish is applied in thin, even coats, usually two to four coats depending on the product and desired durability. Application should begin at the wall farthest from the exit, using a lamb’s wool applicator or a T-bar to maintain a wet edge and avoid lap marks. Between coats, a light abrasion, known as screening or inter-coat sanding, is performed using a fine abrasive pad or 220-grit sandpaper to ensure adhesion and smooth out any dust nibs. After this light sanding, the floor must be thoroughly vacuumed and tack-clothed again before the next coat is applied.
Curing, Final Cleanup, and Long-Term Care
The final stage requires understanding the difference between drying and curing. Drying time is the period until the finish is dry to the touch, typically 24 to 48 hours after the final coat, allowing for light foot traffic. Curing time is the chemical process of polymerization where the finish achieves its maximum hardness and resistance to wear.
Full curing ranges from 7 to 14 days for water-based finishes and up to 30 days for oil-based polyurethane. During this curing period, the finish is still vulnerable to damage. Heavy furniture should not be dragged across the floor, and area rugs must be kept off the surface. Placing rugs down prematurely can trap solvents, slowing the curing process and potentially causing discoloration or an uneven sheen.
Once the finish is sufficiently dry, the plastic sheeting can be removed, and the baseboards and trim can be reinstalled. For long-term care, place felt pads on the bottom of all furniture legs to prevent scratching the finish. Cleaning should be done with products specifically approved for finished wood floors, as harsh chemicals or excessive water can degrade the protective layer over time.