Wooden Office Chair Sanding

Wooden office chair sanding should be carried out according to standardized procedures, with core steps including preparation before sanding, phased sanding, and precautions, as detailed below:

I. Preparation Before Sanding

1. Tool Selection
   • Electric Tools: Angle grinders are suitable for large-area rough sanding, requiring control of force and angle; among sanders, belt sanders are suitable for long, narrow components like chair legs, disc sanders for curved surfaces, and straight sanders, which are small and have light vibration, are suitable for seams and mortise-and-tenon joints.
   • Manual Tools: Sanding blocks (wooden blocks wrapped in sandpaper), wood rasps (flat rasps for planing surfaces, round rasps for shaping curves), cork pads, etc., can handle 'dead spots' that electric tools cannot reach.
2. Sandpaper Selection
   • Sandpaper should be used progressively according to grit (number of sand particles per square inch):
     • Coarse Sandpaper (80-120 grit): Used in the initial sanding stage to remove burrs and tool marks. For softwoods (such as pine), 120 grit is recommended to avoid tearing wood fibers and causing fuzzing.
     • Medium Sandpaper (180-240 grit): Used in the finishing stage to remove rough sanding marks. For example, after sanding black walnut with 180 grit three times, when faint sanding marks are visible under side lighting, switch to 240 grit and sand twice more.
     • Fine Sandpaper (320-600 grit): Used in the polishing stage to enhance surface smoothness. Mortise-and-tenon joints can be sanded in a circular motion with 400 grit, and cherry wood should be lightly sanded with 600 grit before painting.

II. Sanding Steps

1. Rough Sanding
   • Use 120 grit sandpaper to smooth out larger burrs and unevenness, always sanding along the wood grain direction with even force. Softwoods should avoid overly coarse sandpaper to prevent fiber breakage.
2. Medium Sanding
   • Switch to 240 grit sandpaper for overall sanding to eliminate rough sanding marks and achieve a fine surface. Hardwoods like black walnut should be checked for sanding marks under side lighting to ensure no deep marks remain.
3. Fine Sanding
   • Use 400 grit or higher sandpaper for fine polishing until the surface feels smooth to the touch. Mortise-and-tenon joints should be sanded in a circular motion to ensure a tight fit, and cherry wood and other types should be lightly sanded with 600 grit before painting to enhance paint adhesion.

III. Precautions

1. Sanding Direction: Always sand along the grain; sanding against the grain can leave irreversible scratches.
2. Wood Dust Removal: Promptly remove wood dust generated during sanding to avoid affecting subsequent painting results.
3. Special Part Handling: For chair edges and other heavily worn areas, a small angle grinder equipped with a sanding disc can be used for quick treatment, but control the force and angle to prevent damaging the surrounding paint or solid wood surface.
4. Veneered Furniture: Avoid using coarse sandpaper or high-power tools to prevent damaging the surface veneer.