If I use a clay mitt on the car to remove the contaminants, is polishing necessary? Can I use the clay mitt and go right to SiO2? Car has almost zero swirl marks now.
You can, but remember claying can jntoroduce micro swirls. A final polish like menzerna 3800 or CarPro should remove any clay induced marring and most likely will give some extra gloss.
Yes, by all means, if the paint looks fine to your eyes you can seal it up with Si02.
I always polish after claying like spewking mentioned to not only insure any marring is handled but to brighten up the paint before I wax, seal or coat.
