The Ultimate Guide to Sanding Plywood 2024

The Ultimate Guide to Sanding Plywood 2024

Sanding plywood is an essential part of any woodworking project. It involves understanding sanding techniques, such as orbital sanding, hand sanding, and edge sanding, choosing the right grit sandpaper, filling knot holes and gaps, eliminating sanding marks, and cleaning. We have made a comprehensive guide that will take you through the ins and outs of sanding.

Why Sanding Plywood Matters

Sanding plays a crucial role in woodworking projects because it smoothens the surface of the wood, making it ready for finishing. When you cut or shape wood, it can leave rough spots or uneven surfaces. Sanding helps to remove these imperfections, creating a smooth and even surface. Similar to preparing a canvas before painting; sanding prepares the wood for its final treatment, whether it’s staining, painting, or applying a clear coat.

Plywood often has rough edges and surfaces due to its manufacturing process. Sanding smoothens these rough areas, creating a more refined and professional-looking finish. Plywood can have imperfections like patches and knots, which sanding helps to minimize or remove. Sanding also opens up the pores of the plywood, allowing finishes like stains and paints to penetrate more evenly, which enhances the richness of color and depth of the finish. By removing any rough spots or splinters, sanding improves the durability of plywood projects.

Benefits of Sanding Plywood

Achieving a smooth and even surface is crucial for achieving a professional finish in woodworking projects. When you run your hand over a piece of wood, you want it to feel smooth, without any rough patches or uneven areas. Sanding helps to achieve this by removing imperfections and leveling the surface. It’s like smoothing out a rough road before laying down fresh asphalt; sanding prepares the wood for a flawless finish that looks and feels professional.

Sanding enhances the stain absorption and paint adhesion of plywood by opening up its pores. Plywood, being made of multiple layers of wood glued together, can have a tight surface that doesn’t readily absorb stains or allow paint to adhere properly. Sanding roughens up the surface slightly, allowing stains and paints to stick to the surface.

Plywood can be susceptible to damage from moisture, temperature changes, and everyday wear and tear. By smoothing out rough spots and removing any sharp edges or splinters, sanding helps to reduce splintering, warping or bending over time. Giving your plywood project a strong foundation ensures that it looks and works great for years to come.

What is Plywood Made Of?

Plywood is made up of multiple layers of wood veneers that are glued together, with each layer having its grain direction. This gives plywood its strength and stability, but it can present challenges while sanding. The thickness of the veneers can vary, causing uneven sanding results. Since each layer has its grain direction, sanding can sometimes lead to tear-out or uneven smoothing if the direction changes abruptly.

Methods for Sanding Plywood

Orbital Sanding

A power sander with a sanding pad that moves in a circular motion. Efficient for covering large surface areas quickly and evenly, and particularly useful for initial sanding to remove rough spots and imperfections from the plywood surface.

Hand Sanding

Allows for greater control and precision, using sandpaper by hand to smooth out small areas or intricate details that power sanders might miss, refining the surface and achieving a smooth finish.

Edge Sanding

Sanding the edges of plywood pieces with a handheld sanding block or a specialized edge sander to achieve clean edges that seamlessly blend into the overall finish of the plywood project.

midjourney image of a man sanding plywood

Tools and Materials for Sanding Plywood

Sanders

Orbital sanders: Use a round sanding pad that moves in a circular motion, covering a large surface area quickly and evenly. They are versatile and suitable for general sanding tasks, such as smoothing rough surfaces and removing old finishes.

Belt sanders: Feature a continuous loop of sandpaper that moves in a linear motion over two rollers. They are powerful and efficient for removing large amounts of material quickly, making them ideal for heavy-duty sanding tasks like leveling surfaces and removing rough edges.

Hand sanding: Using sandpaper by hand or with a sanding block to achieve precision and control over smaller or intricate areas that power sanders cannot reach easily. Essential for refining surfaces and achieving a smooth finish, especially in detailed woodworking projects.

stack of sandpaper made with midjourney

Sandpaper

Coarse grits (40-60): Suitable for removing large amounts of material quickly, such as leveling surfaces or removing old finishes.

Medium grits (80-120): Ideal for general sanding tasks, including smoothing rough surfaces and preparing wood for painting or staining.

Fine grits (150-240): Used for finishing touches and achieving a smooth surface before applying a final finish. They are also suitable for sanding between coats of finish to ensure a uniform appearance.

Very fine grits (320 and above): Best saved for ultra-smooth finishes and final polishing of surfaces, such as preparing wood for a high-gloss finish.

Safety Equipment

Goggles: Safety goggles protect the eyes from dust and debris while sanding plywood.

Dust mask: A dust mask or respirator helps to filter out airborne dust particles.

Gloves: Gloves provide protection against splinters, sharp edges, and rough surfaces. They also help to improve grip and control when handling sanding equipment.

Additional Materials

Wood filler: A putty-like substance used to fill in gaps, cracks, holes, and imperfections in wood surfaces before sanding plywood and finishing.

Sanding blocks: Used to hold sandpaper securely in place while sanding. Sanding blocks come in various shapes and sizes, including flat blocks for general sanding and contoured blocks for curved or detailed surfaces.

Tack cloth: A sticky, lint-free cloth used to remove dust and debris from surfaces after sanding. It picks up fine particles that may be left behind by sandpaper.

Preparation Before Sanding Plywood

Check for Issues

Knots: Areas where branches intersected the wood grain during the tree’s growth. While knots can add character, they may be harder than the surrounding wood and can cause tear-out or uneven sanding. Check for large or protruding knots that may need to be filled with wood filler.

Splinters: Small, sharp fragments of wood that can cause injury. Check for any raised or rough areas and use sandpaper or a sanding block to smooth them out before continuing.

Unevenness: Variations in the surface level of the plywood, caused by differences in veneer thickness or manufacturing defects. Run your hand over the surface of the plywood to feel for any bumps, dips, or ridges. Use good lighting to identify areas that may require extra attention while sanding plywood.

Surface Cleaning

Remove Dust and Debris: Use a soft-bristled brush or a vacuum with a brush attachment to remove any loose dust and debris from the surface of the plywood. Pay attention to corners, edges, and any crevices where dust may have built-up.

Strip Existing Finishes: If there is paint, stain, or varnish, make sure to strip them away before sanding. Paint strippers or chemical solvents work best. Follow the manufacturer’s instructions carefully, and work in a well-ventilated area.

Clean with Tack Cloth: Gently wipe a tack cloth over the entire surface of the plywood to ensure it’s clean and free of any remaining dust or debris before sanding plywood.

Techniques for Sanding Plywood

Orbital Sanders

Setup and Safety Precautions: Check that you have the appropriate sandpaper attached securely to the sanding pad. Wear safety goggles, a dust mask, and ear protection to protect yourself from dust, debris, and noise.

Positioning: Hold the orbital sander with both hands, keeping a firm grip on the handles. Place the sanding pad flat against the plywood surface, ensuring even contact across the entire area.

Circular Motion: Orbital sanders rotate in a circular pattern while simultaneously moving back and forth. Move the sander in small circular motions, overlapping each pass slightly.

Random Orbital Motion: Random orbital sanders (AKA dual-action) combine both rotary and orbital motion. The sanding pad spins in a circular motion while also moving in an elliptical pattern. This helps to prevent swirl marks and ensures a smoother finish. Move the sander in straight lines or gentle arcs, avoiding excessive pressure or aggressive movements.

Progression: Use a coarse grit sandpaper to remove any roughness or imperfections. Move to finer grits, making sure to sand evenly and consistently across the entire surface. Keep the sander moving at a steady pace to prevent uneven sanding or over-sanding in one area.

Dust Extraction: Many orbital sanders come with built-in dust collection systems. Empty the dust collection bag or container regularly.

Hand Sanding

Choose the Right Sandpaper: For the majority of plywood – starting with a 120 grit and progressing to a 220 grit after applying the finish. If the material is particularly coarse – start with 80 grit before filling in any voids. 

Sanding Block: Wrap the sandpaper around a sanding block to provide stability and even pressure. A sanding block helps to distribute pressure evenly, preventing uneven sanding and stopping your hand from getting tired or injured.

Use Firm but Gentle Pressure: Avoid pressing too hard, as this can lead to uneven sanding and premature wear of the sandpaper. Let the sandpaper glide smoothly over the plywood surface, using long, even strokes.

Sand with the Grain: This will prevent scratching. Sanding against the grain can result in uneven sanding and leave behind unsightly marks. Follow the direction of the wood grain, moving the sandpaper in straight, parallel strokes.

Change Sandpaper Frequently: As sandpaper becomes worn or clogged with dust and debris, it becomes less effective at sanding plywood.

Tips for Sanding Plywood

Filling Knot Holes and Gaps

Choose the Right Wood Filler: Select a wood filler that matches the color of the plywood or can be stained to blend into the wood.

Prepare the Surface: Make sure that the surface of the plywood is clean. Use a brush or vacuum to remove any loose particles and wipe the surface with a tack cloth.

Apply Wood Filler: Use a putty knife to apply the wood filler to the knot holes or gaps. Press the filler firmly into the voids until they are level with the surface. Smooth out any excess filler with the putty knife.

Let the Filler Dry: Check the manufacturer’s instructions. Depending on the type of filler used and the size of the voids, this may take anywhere from a few hours to overnight.

Sand the Surface: Use sandpaper to sand the filled areas until they are smooth and level. Start with a coarse grit sandpaper to remove any excess filler and gradually progress to finer grits for a smoother finish.

Inspect and Touch Up: If any imperfections or low spots are visible, apply additional wood filler as needed and repeat the sanding process until the surface is flawless.

Sanding Plywood Edges

Secure the Plywood: Place the plywood piece securely on a workbench or clamped in a vice to prevent it from moving while sanding.

Sand with Light Pressure: Let the sandpaper do the work. Avoid pressing too hard, as this can lead to splintering or tear-out, or misshape the plywood. Move the sandpaper along the edge in long, even strokes, applying consistent pressure.

Sand Along the Grain: Sanding against the grain can cause the wood fibers to lift and tear, resulting in rough edges. Follow the natural direction of the wood grain, moving the sandpaper in straight, parallel strokes.

Finish with Fine Grit Sandpaper: Refine the surface further and remove any remaining scratches or imperfections.

Removing Sanding Marks

Progressive Sanding: Moving from rougher to finer grit will help to remove the scratches left by the previous grit, resulting in a smoother finish.

Sand with the Grain: Always sand plywood with the direction of the wood grain to prevent cross-grain scratches. Sanding against the grain can leave visible marks and affect the final finish.

Use Light Pressure: Pressing too hard can cause the sandpaper to dig into the surface unevenly, resulting in visible scratches and imperfections. Let the sandpaper do the work and maintain a consistent pressure across the surface.

Inspect and Adjust: If you notice any areas that require additional sanding, go back and focus on those areas. Take your time and be thorough in your inspection to ensure a flawless finish.

Use a Sanding Block: A sanding block helps to distribute pressure evenly across the surface, resulting in a smoother and more uniform finish. Use long, even strokes.

Final Sanding with Fine Grit: Refine the surface further and remove any remaining sanding marks. Fine grit sandpaper helps to achieve a smooth and polished finish, enhancing the overall appearance of the plywood surface.

Cleaning Up After Sanding Plywood

Vacuum or Brush: Remove loose dust and debris. Pay attention to corners and edges where dust may accumulate.

Compressed Air: Use compressed air to blow away dust from hard-to-reach areas or intricate details on the plywood surface. Hold the nozzle of the compressed air canister at a distance to avoid damaging the wood or blowing dust back onto the surface.

Tack Cloth: Wipe down the plywood surface and remove any remaining dust and debris.

Our Recommended Products for Sanding Plywood

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Additional Resources for Sanding Plywood

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