Professional Headlight Restoration and UV Protection Guide

Thoroughly wash the headlights and surrounding panels using a high-foaming car soap to remove road grime, salt, and bug splatter. Use a clay bar on the lens surface to remove embedded metallic fallout or red dust. This prevents dragging large contaminants across the plastic during the sanding phase, which would cause deep, unrecoverable scratches.

Apply two to three layers of automotive masking tape to the paintwork, chrome trim, and rubber seals surrounding the headlight. In the high heat of summer, ensure the metal is cool before taping to prevent adhesive transfer. Open the bonnet to gain better access to the top edge of the lens and mask any exposed engine components.

Submerge your 800, 1200, and 1500 grit sandpaper sheets in your lubricant solution for at least 15 minutes prior to use. This softens the paper backing and ensures the abrasive particles are evenly lubricated, reducing the risk of 'pig-tail' deep scratches and heat build-up during the manual sanding process.

Use a high-lumen torch to inspect for internal moisture or 'crazing' (internal cracks). If the damage is on the inside of the lens, restoration will not be successful. Confirm the surface temperature is below 30°C; if the car has been in the sun, use a fan or move it to a shaded, dust-free garage to allow the polycarbonate to stabilise.

Using the 800-grit soaked paper, begin sanding in a horizontal motion. Use light, even pressure and plenty of lubricant. You will see a 'slurry' of yellow/milky liquid; this is the oxidised layer being removed. Continue until the slurry turns white and the entire lens has a uniform, dull frosted appearance. Wipe clean to inspect progress.

Switch to 1200-grit paper. Crucially, change your sanding direction to vertical. By switching directions between grits, you can visually confirm when the previous grit's scratches have been fully replaced. Sand until all horizontal 800-grit marks are gone. Keep the surface saturated with your soap/water mix.

Revert to horizontal strokes with 1500-grit paper. This stage begins to smooth the 'peaks' created by the coarser papers. The lens will start to look slightly more translucent when wet. Ensure you spend extra time on the edges where UV damage is often most stubborn near the bonnet line.

Switch to 2000-grit. At this stage, the slurry should be very fine and purely white. The goal is to create a surface so smooth that a machine polisher can easily remove the remaining haze. Use circular motions for this final hand-sanding stage to blend the scratch pattern.

If available, use a 3000-grit foam-backed disc. This 'damp sanding' step is the secret to a professional finish. It refines the polycarbonate to a point where it looks almost clear when wet, significantly reducing the heat generated during the subsequent mechanical polishing stage.

Dry the lens completely with a microfibre cloth. The headlight should look perfectly uniform and 'frosted' like etched glass. Any shiny spots indicate areas where the old coating wasn't fully removed; if found, you must return to the 800-grit stage in those specific spots.

Apply 3-4 pea-sized drops of heavy-cut compound to a firm foam or wool polishing pad. Set your DA polisher to a medium speed (approx. 3500-4000 OPM). Work in a 15cm x 15cm section, moving slowly. The compound will turn from opaque to translucent as the abrasives break down. Do not let the plastic get hot to the touch.

Switch to a finishing pad and a fine polish. This removes any 'haze' or 'holograms' left by the heavy compound. Use light pressure and slightly faster arm movement. After 2-3 passes, the lens should achieve 95-100% optical clarity. Wipe with a clean microfibre to check for any remaining sanding marks.

This is the most critical step for longevity. Spray a 15% Isopropyl Alcohol solution onto a fresh microfibre and wipe the lens thoroughly. This removes all polishing oils and lubricants. Without this, your UV sealant will not bond to the polycarbonate and will fail within weeks under the sun.

Apply your chosen ceramic coating or UV sealant to an applicator block. Wipe onto the lens in straight, overlapping horizontal lines, then vertical lines to ensure 100% coverage. Most professional coatings require 30-60 seconds to 'flash' before a light buff with a clean microfibre is needed. Follow the specific product's flash-time instructions carefully.

The vehicle must remain in a dry, dust-free environment for at least 4-12 hours (depending on the product). Do not wash the vehicle or expose the headlights to rain or morning dew during this period. In high humidity coastal areas, extend the curing time to ensure the cross-linking of the ceramic molecules is complete.