Finishing and Polishing Epoxy Resin for a Professional Shine

Why Finishing Matters

Resin straight from the mould often has small imperfections. Edges may feel sharp, patches may appear cloudy, or the surface can be uneven. Sometimes there are tiny bubbles trapped underneath, or a few specks of dust that landed while it cured. Finishing removes these flaws, smooths the surface, and prepares it for polishing.

It can be tempting to skip this step, especially after waiting for it to harden. But sanding and polishing completely transform the look of the piece. A dull coaster can turn crystal clear. A jewellery pendant catches the light properly. A tabletop gains depth and reflection. This stage takes your work from basic to impressive.

Check the Cure Before You Start

Before sanding or polishing, make sure the resin has cured completely. Not just dry on the surface, but hardened throughout. Most resins need at least 24 hours at room temperature, though thicker pours or cool rooms can take longer. Press gently with a fingernail. It should feel solid, not rubbery or soft. If it bends, give it more time. Starting too soon can ruin the finish.

Clean the Surface

Wipe the piece with a lint-free cloth to remove any dust or fingerprints. If there is residue, use a little soapy water, then let it dry completely before sanding. Avoid alcohol wipes at this stage, as they can dull the surface or react with the resin.

Sanding: The Foundation of a Smooth Finish

Sanding is where most of the improvement happens. You are not removing large amounts of resin, just smoothing out imperfections and scratches until everything feels even. Move through grits gradually for the best results.

If the surface is rough, start around 400 grit. If it feels fairly smooth already, begin at 800. Then move up through 1000, 1500, 2000, and finish around 2500 or 3000 grit for a glass-like effect. You will see the change from frosted, to hazy, to smooth as you go.

Wet Sanding or Dry Sanding

Wet sanding gives a cleaner, more even result. It keeps dust down and prevents paper from clogging. Use clean water, and add a drop of washing-up liquid to help the sandpaper glide. Dip the paper often, or lightly spray the surface as you go. Keep it wet and keep it gentle.

Dry sanding is fine for small touch-ups, but it can create more mess and visible scratches. If you dry sand, wipe the surface frequently to check progress.

How to Sand Effectively

• Sand in small circles or even back-and-forth strokes, using light pressure.
• Rinse both the paper and the resin often to remove grit and prevent marks.
• Change direction between grits, for example, sand horizontally at 800 then vertically at 1000, so you can see when old scratches disappear.
• Use a flat sanding block on even areas and wrap paper around your fingers for curved sections.
• Take your time. Skipping grits or hurrying will leave marks that polishing cannot remove.

Checking Your Progress

After each grit, dry the surface and inspect it under good light. Scratches from the previous step should be gone before moving on. If you still see lines or dull areas, continue at the same grit. The goal is a completely even matte finish with no visible marks before polishing begins.

Polishing the Resin

Once the surface is smooth and uniform, it is time to bring back the shine. You can polish by hand or with a rotary tool. Both methods work, it depends on the size of your project. Small pieces like pendants or coasters polish well by hand. Larger items like trays or tables benefit from a machine.

Use a polishing compound made for plastics or automotive clear coat. These are gentle and will not scratch. Apply a small amount to the surface and buff with a soft cloth or foam pad in slow, overlapping circles. You should see the shine return gradually. If you use a machine, keep the speed moderate and keep it moving to avoid creating heat.

Hand or Machine Polishing

Hand polishing gives more control and is perfect for detailed or curved pieces. You can feel the change in texture as you go. It takes more time but can be very satisfying. Machine polishing suits larger surfaces or repeat work where you want consistent results quickly. Either way, wipe away compound residue with a clean cloth between passes until the surface looks glossy and clear.

Optional Final Coat

For a deep, glass-like look, you can add a final clear coat of resin, often called a doming layer. Mix a small batch of clear resin, pour a thin layer, and allow it to level itself naturally. Keep it free from dust while curing. This method adds a rich depth that sanding and polishing alone may not achieve, especially for flat decorative items.

Cleaning and Maintaining the Finish

After polishing, handle the piece with care. Use clean hands or gloves to avoid fingerprints. If the piece is functional, like a tray or coaster, wash it gently with mild soap and water. Do not use harsh cleaners or alcohol-based products, as they can dull the surface. To maintain the gloss, you can lightly rebuff the surface every few months or just dust it with a microfiber cloth.

Common Mistakes to Avoid

• Starting too coarse: beginning with low grit paper removes too much material and makes later polishing harder.
• Skipping grits: each step removes marks from the previous one. Missing a grit leaves scratches that will remain visible.
• Overheating: excessive friction can soften or distort the resin. Keep tools and hands moving.
• Wrong polish: some compounds are too strong and cause dulling. Use fine polishes made for resin or plastic.
• Rushing the cure: polishing uncured resin can cause smearing and drag marks. Always wait until it is solid through.

Finishing Edges and Corners

Edges need their own care. Lightly sand them to remove sharpness or flashing. For domed pieces, a small bevel looks professional and feels smoother. Use fine paper or a small file to shape, then polish the edges separately with compound and cloth.

Bringing It All Together

Finishing and polishing resin is not difficult once you understand the rhythm. Sand, check, rinse, polish, and check again. Each step builds on the last. When you take your time, the results speak for themselves. Watching the dull haze fade and the clarity return is one of the most satisfying parts of resin work.

Good resin finishing comes from patience. If you give it time, your pieces will look smooth, reflective, and professional every time.