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How to sand back floorboards?

Published in Floorboard Sanding 4 mins read

To sand back floorboards, you typically follow a multi-stage process involving different sanders and sanding directions to effectively remove old finishes and prepare the wood for a new treatment.

The general process begins with diagonal sanding passes, followed by sanding along the grain, and finally tackling the edges and corners. This comprehensive approach ensures a smooth, even surface.

Step-by-Step Floorboard Sanding Process

Sanding floorboards is a meticulous task that requires patience and the right equipment. Here's a breakdown of the key stages:

1. Initial Diagonal Sanding Passes

According to expert recommendations, after an initial diagonal pass (e.g., at a 45-degree angle to the boards), you should:

  • Sand the boards diagonally in the opposite direction. This cross-grain sanding helps to remove the old finish and level out any high spots or imperfections across the floorboards. Using a powerful sander like a drum sander for this stage is common practice, starting with a coarser grit sandpaper.

2. Sanding Along the Grain

Once the diagonal passes are complete and the old finish is largely removed:

  • Work along the grain of the boards. This crucial step helps to eliminate any cross-grain marks left by the previous diagonal passes and further smooth the wood. For this stage, you would typically switch to a finer grit sandpaper on your drum sander. Sanding with the grain ensures a uniform texture, preparing the wood for staining or sealing.

3. Edge Sanding

After the main floor area has been thoroughly sanded:

  • You can start on the edges with the edging sander. A specialized edging sander allows you to reach areas that a larger drum sander cannot, such as along skirting boards, in corners, and around radiators. You'll use a similar progression of grits as with the main floor area, ensuring the edges blend seamlessly with the rest of the floor.

Essential Equipment for Sanding Floorboards

To achieve a professional finish, you'll need a few key pieces of equipment:

  • Drum Sander: This is the primary tool for sanding the main body of the floor. It's powerful and efficient for removing old finishes and leveling the floor.
  • Edging Sander: As mentioned, this specialized sander is essential for reaching the perimeter of the room and other tight spaces that the drum sander cannot access.
  • Detail Sander/Delta Sander: For very tight corners or intricate areas, a small detail sander or even manual sanding might be necessary.
  • Sandpaper (Various Grits): You'll need a range of sandpaper grits, typically starting coarse (e.g., 40-60 grit) to remove the old finish and progressively moving to finer grits (e.g., 80-120 grit) for a smooth finish.
  • Dust Masks & Safety Glasses: Essential personal protective equipment (PPE) to protect against wood dust and debris.
  • Ear Protection: Drum sanders can be very loud.
  • Vacuum Cleaner: To clean up dust between sanding stages.

Sanding Stages Overview

Here's a simplified table illustrating the typical progression of sanding stages:

Stage Primary Direction Sander Type (Common) Purpose Typical Grit Range
Rough Sanding Diagonal Drum Sander Remove old finish, flatten surface 40-60 grit
Intermediate Sanding Along the Grain Drum Sander Smooth out diagonal marks, further level 80-100 grit
Fine Sanding Along the Grain Drum Sander / Rotary Sander Final smoothing, prepare for finishing 100-120 grit
Edge Sanding Follow perimeter Edging Sander Sand areas inaccessible to drum sander Matched to main floor grit
Detail Sanding Manual / Variable Detail Sander / Hand Block Tackle tight corners and intricate spots Matched to main floor grit

Practical Tips for Best Results

  • Preparation is Key: Before you begin, ensure the floor is clear of all furniture. Hammer down any protruding nails and remove staples to prevent damage to the sander and sandpaper.
  • Test a Small Area: If you're unsure about the aggressiveness of a particular grit or the technique, test it in an inconspicuous area first.
  • Overlap Your Passes: When using a drum sander, overlap each pass by about one-third of the drum's width to ensure even sanding and prevent visible lines.
  • Keep Moving: Never let a running sander sit stationary on the floor, as it will create depressions and uneven patches.
  • Clean Thoroughly: Vacuum the floor meticulously after each grit change to remove all dust and debris. This prevents coarser particles from scratching the floor during finer sanding stages.
  • Inspect Regularly: Continuously check your work for evenness and consistency. Use a bright light to highlight any missed spots or imperfections.

By following these steps, you can effectively sand back your floorboards, preparing them for a beautiful new finish.