First thing you should always do before you sand anything is make sure the surface is clean, wash all parts before sanding anything, as the littlest piece of dirt could leave a line in the clear and would be seen after the airbrushing is done. I wouldnt use a hard rubber block to do sanding on clear best thing to use is a sanding sponge because of curves and edges and such. Most deff wet sand it, it will be alot smoother and you can see how far down you are going on the clear, keep washing the surface down with water as you are sanding to remove debris and see the entire surface. Make sure you are not sanding in little areas do longer strokes and at like a 45 degree angle both ways to keep from leaving waves. Be careful around edges because you will burn through the clear faster in those areas. I would always start out with finer grit paper and work my way down like dave said start off with 2000 and if it isnt doing much go down to 1600 then 1200 and so on but dont go below 1000. Just remember the higher number grit the finer it will be thus making it smoother but taking longer to do. I would suggest asking whoever is doing your airbrushing what they suggest as most artist tend to be somewhat anal about the surface they are working with. Best of luck lets us know how it comes out.
