Are you swirled out that bad you need to start out with fg400? After polishing, especially after using Menzerna polishes, I'd give it a quick wash before applying Sonax PNS - a lot of polishing oils in Merzerna products...
When using the netshield, do I use Sonax fg400> Netshield> Sonax Brilliant Shine? Are they the correct steps?
Are you swirled out that bad you need to start out with fg400? After polishing, especially after using Menzerna polishes, I'd give it a quick wash before applying Sonax PNS - a lot of polishing oils in Merzerna products...
Since your car is black and depending on how bad your swirls are I would go in this order. Wash, clay, compound., polish, IPA/Eraser, SPNS and the BSD. You will be very happy w/ your results. What aggressiveness of the compound you go with will depend on what shape your paint is in.
The polish I use is menzerna's SF4500. It is on the oily side so I would do an IPA wipe down afterwards then apply SPNS and BSD. This will insure your paint is clean and SPNS will bond properly to your paint which in turn will make it last longer.