Clean the surface
Begin by cleaning the sculpture with a mild glass cleaner and a soft, lint-free cloth. This will remove any dirt or debris that could potentially worsen the scratches.
Assess the depth of the scratch
Examine the scratch closely to determine its depth. If the scratch is shallow, you may be able to remove it by polishing the area. Deeper scratches may require you to go back and complete all the grinding/polishing steps again.
Use a glass polishing compound
For shallow scratches, apply a small amount of cerium oxide to the scratched area. The most effective way to remove the scratch is by using a handheld polisher with a felt pad. You’ll need to mix a small amount of cerium oxide with water (for scratches, a good ratio is 2 parts of cerium oxide and 1 part of water).
Add a tiny amount of the slurry paste to the scratch (or the pad). Then use the handheld polisher to apply the compound in a circular motion — or alternating vertical and horizontal movements. Make sure you use just a small amount of paste to target the area. (You want to keep water to a minimum, especially when using an electric handheld machine.)
Repeat the process until the scratch begins to fade. When the surface starts drying, spray it with water to make the compound work again. Be patient and apply a bit of pressure while you polish, but avoid excessive force and be careful not to overheat the area, as it could cause further damage.
Rinse and inspect
Once you’ve polished the scratched area, rinse it with water and dry it with an air compressor or a clean cloth. Inspect the sculpture under proper lighting to determine if the scratches have disappeared. Repeat the process if necessary. Removing a scratch may take quite a while, so be patient.
Go back to grinding
When the polishing process doesn’t yield satisfactory results, the scratch may be too deep. You may have to go back to previous grinding stages with silicon carbide (or diamond pads) and start the process over until you reach the cerium oxide stage again.
Here you can see how I do it with a handheld polisher and a felt pad -> Watch on Instagram