Split off just a golfball size amount at a time and keep the rest in a bag. The clay bar is not a substitute for buffing. There are videos on of how to. Meguires Mirror Glaze with a power buffer.
Clay bars usually come in sizes ranging from 2–oz (57–2g). The oz (g) size is more than enough for car, and is a very manageable piece of clay to work with. Lubricants aid the clay bar in lifting particles and allow the clay bar to move freely from raking roughly across the paint and causing possible scratches. Detailing clay can be natural or synthetic, though most manufacturers utilize synthetic clays. If you wash your car and it feels rough, you need to use the clay.
Learn how to use a clay bar and why you should be claying regularly. Clay bar lubricants are formulated to work with the clay bar without impacting the integrity or cleaning abilities of the synthetic clay. Car shampoos and car wash soaps can break down the clay and shorten its lifespan. To many, claying is a magical and mysterious process that only the professional detailers use. They have heard that using a clay bar will remove contaminants and provide a very smooth finish, but they are reluctant to try it.
A Clay Bar Treatment is the process of using a clay bar to remove containments from the surface of your car.