what grit should i be using to sand single stage (color + hardener) for clear coat?

im doing a solid black car for a customer and he wants the finish like a mirror. normally i would p120 my high build primer, then refine and finish on p800 wet. base coat then 3 coats of clear and wet flat it.

sound about right? will have a play around on some old filler caps first to see what it looks like. if it wont go much flatter than my normal base+clear jobs i wont bother. must be flat though, always get a tiny bit of texture in the basecoat and i dont want a single bit for this particular job

what sort of grits can you get away with wet flatting 2k color down before you start to see sanding marks in the base through the clear?

aaran wrote:......
im doing a solid black car for a customer and he wants the finish like a mirror. normally i would p120 my high build primer, then refine and finish on p800 wet. base coat then 3 coats of clear and wet flat it.

sound about right? .....

If this has worked for you in the past, I'd continue with it. Personally I've never had
sanding scratches show with anything above p400 wet. Black will show up any
imperfections though, more than any other color. The polishing will be critical
to getting the swirl marks out of the black.

If your single stage is a urethane, there's no reason to sand it first.
Most like to wait 3 hrs to overnight before clearing over.
that is mainly to not disturb any of the metallics.
I clear over urethane all the time, I never sand it.
If it's a metallic and you sand
it first you may make a mess if it sands into the metallic,
sometimes it makes streaks and/or halos.
Remember, when clearing a urethane, the clear is the same thing,
it's a urethane too.

I shot these in SS urethane and applied one coat of clear as I never painted with clear and was dying to shoot some clear.

My data sheet said to wait 6 hrs for metallics and do within 24 hrs. Still holding up well 3 yrs later. Always pays to follow your data sheet.

done many a black car before, come out like this with a base+clear job

thing is there is always a tiny bit of texture in the base when you lay it (the above one i dusted the paint on super super thin coats, i think i put around 6 on that) but if you go mega close up to the finish you can make it out through the clear.

reason for going gloss 2k black first was to actually flat out the gloss so its like glass then clear over, then once thats flatted down you have mega flat clear over mega flat gloss ie: complete mirror.