There seems to be a lot of confusion over what hand application method works best or is the safest (straight lines vs. circular motions). The major difference between applying products in a circular motion verse straight lines is your coverage. I feel a circular motion allows you to work in a product more evenly and hit areas at multiple angles for a more thorough application. This is especially important when polishing for best results. The same thing applies for a wax or sealant that you want to be applied to every microscopic peak and valley in the clear coat. The Porter Cable 7424 moves in an oscillating pattern which is basically a tight circular motion meant to replicate circular hand movements. This results in very good product breakdown and coverage for a thorough application.
Some people feel that a circular motion will create micro-scratches in a circular pattern in the clear coat. Therefore with that logic, they feel straight hand motions will only create straight micro-scratches that are less noticeable to an observer. If you are creating micro-scratches in the clear coat your problem lies in your prep work or products and tools used during the process, not your technique. If micro-scratches are being added you may be experiencing one or more of the following problems:
- You are using a contaminated applicator pad
- You are using a non-paint safe applicator pad
- You are using a contaminated removal towel
- You are using a non-paint safe towel
- You are applying a product over a contaminated area
With any one of the above situations you can easily be grinding in contaminates in to the clear coat which can cause micro-scratches regardless of your technique. Additionally the same concept is true if the applicator or removal towel you are using is too coarse. Some common problems we see are people using an applicator pad or removal towel that has old and dry product (i.e. wax) in it or a large piece of contamination that’s abrasive. Contaminates and old product can become lodged in an otherwise good applicator or removal towel and make it a potentially dangerous tool. Contaminates left on the surface of your vehicle can also be very dangerous. To decrease the risk of grinding in contaminates make sure you do a thorough wash with a pre-wash degreaser and use a clay bar to deep clean the micro-ridges of the clear coat. When wiping an area that has contamination you may loosen the contamination or part of it. These contaminates can then be grinded in to the clear coat or become lodged in your applicator or removal towel. It’s very important to regularly inspect all of your microfiber towels, applicators, buffer pads, etc. for contamination that could be potentially dangerous and replace as needed.

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Greg @ Detailed Image