Sanding and Finishing Tools Guide for Epoxy Resin
Why Finishing Matters in Resin Art
The surface finish of a resin piece is what separates a professional result from an amateur one. Even a beautifully poured piece with stunning color can look dull, scratched, or uneven if the finishing process is rushed or skipped. Sanding and polishing are the steps that bring out the depth of the color, restore clarity to the surface, and create the high-gloss finish that makes resin art look truly luxurious.
At Trayz N Beyond, every piece goes through a multi-step finishing process before it leaves the studio. This guide breaks down the tools and techniques involved.
When to Sand Resin
Resin should only be sanded after it has reached full cure. Sanding partially cured resin will clog your sandpaper, create a gummy residue, and potentially damage the surface permanently. Most pieces are ready to sand after 72 hours at room temperature, though thicker pours or cooler environments may require additional cure time. When in doubt, wait an extra day.
Sandpaper Grits and Progression
Sanding resin requires a progression through multiple grits, starting coarse and finishing fine. Each grit removes the scratches left by the previous grit, gradually refining the surface until it is smooth enough to polish to a high gloss.
Coarse Grits: 120 to 220
Coarse grits are used to remove significant surface imperfections such as drips, runs, uneven edges, or mold lines. Start with 120 or 150 grit if you have major imperfections to address, or 220 grit if the surface is relatively smooth coming out of the mold. Coarse sanding leaves visible scratches that will be removed in subsequent steps.
Medium Grits: 320 to 600
Medium grits refine the surface after coarse sanding and begin to smooth out the scratch pattern. Work through 320, 400, and 600 grit in sequence, spending enough time at each grit to fully remove the scratches from the previous one before moving on.
Fine Grits: 800 to 2000
Fine grits bring the surface to a near-polish state. At 800 grit the surface will appear uniformly matte. By 1500 to 2000 grit the surface will begin to show a slight sheen. This is the range where wet sanding becomes most effective.
Ultra Fine Grits: 2500 to 5000
Ultra fine grits are used immediately before polishing compound and produce a surface that is almost clear. At 3000 to 5000 grit the surface will have a noticeable gloss that polishing compound will bring to a full mirror finish.
Wet Sanding
Wet sanding involves keeping the sandpaper and the resin surface wet with water during sanding. This serves two purposes. First, the water lubricates the surface and reduces friction, which produces a finer scratch pattern at each grit. Second, the water flushes away sanding dust and resin particles that would otherwise clog the sandpaper and reduce its effectiveness.
Use wet and dry sandpaper, which is designed to be used with water and will not fall apart when wet. Keep a spray bottle of water nearby and mist the surface frequently during sanding. Wipe the surface clean between grits to check your progress and ensure the previous scratch pattern has been fully removed before moving on.
Polishing Compounds
After sanding through your full grit progression, polishing compound is used to remove the fine scratches left by the highest grit sandpaper and bring the surface to a high-gloss finish. Polishing compounds contain very fine abrasive particles suspended in a liquid or paste carrier.
Plastic Polish
Plastic polish is the most commonly used polishing compound for resin because resin behaves similarly to acrylic plastic when being polished. Apply a small amount to a soft microfiber cloth or foam polishing pad and work it into the surface in circular motions. Buff until the compound clears and the surface reveals a high gloss.
Automotive Polishing Compound
Automotive polishing compounds designed for clear coat finishes also work excellently on resin. They are available in cutting, polishing, and finishing grades that correspond to different levels of surface refinement. A two-step process using a cutting compound followed by a finishing polish produces exceptional results.
Power Tools for Finishing
For large pieces or high-volume production, a random orbital polisher with foam polishing pads significantly speeds up the polishing process and produces more consistent results than hand polishing. Use low to medium speed settings to avoid generating too much heat, which can soften the resin surface.
Final Protective Coating
After polishing, a final protective topcoat can be applied to seal the surface and add an additional layer of gloss and scratch resistance. UV-resistant clear coats designed for plastics or automotive finishes work well over polished resin. This step is optional but adds longevity to the finish, especially for functional pieces that see regular use.
Learn More
Finishing is the final step that makes every Trayz N Beyond piece shine. Explore the Studio Tools Overview for guides on all the tools I use. Have a question? Contact me directly or shop all products.