August 26, 2019

Achieving the Ideal Surface Finish: Car Polishing Tips

Car polishing is widely considered something of an art form, largely left to skilled professionals with years of experience in paint correction and surface finishing. Professional detailers are trusted to maintain, and in some cases recover, the depth of color and shine of a vehicle’s paintwork. This requires small amounts of surface material to be carefully removed via mechanical polishing, eliminating minor defects (holograms, scratches, swirls, etc.) Yet there is also a point of no return: polishing will eventually reduce the protective capabilities of clearcoat until they virtually disappear, which will demand more intensive surface treatment and refinishing to correct.

Striking a balance between the two is key to achieving the ideal surface finish through car polishing. In this blog post, Saint-Gobain goes over some of the basics of car polishing and surface finishing.

Car Polishing

Clear Coat Surface Finishing: The Basics

Any car manufactured or repainted in the tail-end of the 20th Century will have clearcoat as standard. Clearcoat is the uppermost layer of paint on automotive bodywork. It is translucent, glossy, and typically deposited at a thickness of around 25 micrometers (μm) or microns. Thinner than the average human hair (~75 μm), this layer imparts high gloss and a measure of mechanical protection from various common phenomena (scratching, weathering, etc.). It is also extremely hard, which makes hand-polishing practically unfeasible.

Rotary and orbital buffers are now consummate tools in the detailer’s arsenal when it comes to automotive surface finishing; especially clear coat correction. However, their performance is still heavily reliant on the skill of the detailer, the nature of the polishing compound, and the type of pad used.

Different Types of Polishing Pads

Various polishing pads are available to detailers, but the three most commonly used in automotive surface finishing are:

  • Foam polishing pads are the most common of the different types, owing to their versatility and ease-of-use. Whether the pad absorbs material or not is dependent on the porosity of the foam structure, while performance is also affected by the pad stiffness.
  • Microfiber pads are generally more aggressive than foam, producing more friction and pressure while absorbing less material.
  • Wool is coarser than foam, which typically imparts a higher cutting-action. Yet it is not as cheap to manufacture nor easy to maintain, so typically cost more for the end-user.

Polishing compounds are applied evenly to the pad surface, priming it for use. The rotary/orbital motion and speed of rotation cause abrasive particles within the compound to abrade the surface of the clear coat and remove nanoscale amounts of material.

Outlining Polishing Compounds

Much like the choice of the pad, the choice of polishing compound largely depends on the scale of the defect/defects that need to be removed. Coarser-grit polishing compounds provide a higher cutting action for more severe flaws, while fine products offer a higher quality surface finish. You can learn more about finding a balance between cutting-action and finish in our previous blog post Automotive Polishing: Balancing Cut Rate with Surface Finish.

The challenge at this stage is removing the right amount of material to reduce and eliminate defects, without stepping into the territory of over-polishing which would mandate repainting. This requires careful consideration of not just the compound used, but the underlying abrasive particles within the product.

Abrasive Particles from Saint-Gobain

Saint-Gobain Surface Conditioning is a world leader in particle science and engineering, providing a range of abrasive materials tailored specifically for the automotive sector. We can provide custom solutions for your polishing product, to help end-users reach the ideal surface finish.

If you have any questions about our IDEAL range of abrasive materials, simply contact a member of the Saint-Gobain team today.