When you say buff:
What products do you plan on using?
What kind of 'buffer' do you have?
- Rotary
- Dual-Action
- Orbital
The reason I ask is you will need
at least a dual action polisher with foam pads and a medium-cut polish to remove any marring caused by aggressive clay. A Sears orbital (a.k.a. wax spreader) won't do it. I prefer to spend more time claying than add an extra polishing step.
That being said, Meguiar's makes an aggressive clay available here:
Meguiars Professional Detailing Clay Aggressive
Most likely your local store will only carry the medium and fine grades of Clay Magic, which are not as aggressive as this.