Yes, manual car wash brushes can potentially scratch paint, especially if they're made from stiff or abrasive materials. Even soft-bristled brushes can trap dirt and debris, which may lead to swirling or scratching if not used carefully. To minimize the risk:

• Choose Soft Brushes: Opt for brushes specifically designed for automotive use, ideally with soft bristles.
• Rinse Thoroughly: Always rinse the brush before using it on your car to remove any trapped dirt.
• Use Soap: Always wash with a quality car soap to provide lubrication.
• Gentle Technique: Use gentle, straight strokes rather than circular motions to reduce the chance of scratches.

For the best results, many detailers recommend using a wash mitt or sponge instead.

Use the right products
One of the worst things you can do for your car is to use household cleaners to scrub dirt and stains from the finish, so ditch the dish soap and laundry detergent. These products aren't designed to safely remove dirt and stains from your car, and, in most cases, their harsh chemical formulas will do a lot more harm than good to any wax you may have on your car.

You should also steer clear of wash cloths, bath towels and shower sponges. These cleaning accessories may be great for exfoliating your skin, but they're too rough to use on your car. Plus, the bulky fibers of most cotton cloths don't safely encapsulate dirt and soils. Instead, they drag these contaminants across the finish, leaving tiny scratches and swirls that dull the transparency of the clear coat.

Don't skimp on the soap
Car wash soap creates a slippery, protective barrier around the surface of your car to reduce the friction between your wash mitt and the finish, so use it generously. When it comes to preventing scratches and swirls, more is more. At a minimum, use the concentration of car wash soap specified on the back of the bottle.

Fill your bucket with a strong stream of water to create as much foam as possible. Foam helps to cushion and protect the surface of your car so that dirt and other contaminants don't scratch the paintwork.

Pro Tip: Most car wash soaps are measured in ounces per gallon to account for different bucket sizes, so pay attention to how many ounces per gallon the product label tells you to add to your cleaning solution. Then multiply that amount by the number of gallons your car wash bucket holds to get the correct concentration of car wash soap.