I wish I could be of help but I just dont use the products you are using. In my system I use everyday I sand bare wood to 180. Then 320 between lacquer coats. I was taught ( from finishing seminars) that you dont want to use super fine grits between coats because you are basically polishing the surface too much which can cause adhesion problems. But like I say that is using my products. These guys have been doing this forever so take their advice and run with it. Just kinda wanted to explain why I dont chime in on these finishing topics too often,
This.
we need to know your exact finish system and can then make good suggestions for you.
On guitars, we went for a glassy, wet oil looking finish. That, on wood, is a challenge.
For solid colors, I used a Behlen sanding sealer to fill the grain. Two or three coats with sanding between. No finer than 320 grit for this or you will have bonding problems of the paint.
Once fully dry (no more solvent smell) I applied automotive catalyzed acrylic eurethane "one step" paint. One step means it does not require a clear. I did on occasion use two-step systems which require clear coat for accurate color and gloss.
The paint got wet blocked, 400, 600, 1200 and then to the buffing wheel. (black got extra sanding steps in between as well).
For two-step systems once there is enough paint to cover (usually 2-3 full wet coats) clear is applied. You do not touch the paint prior to clear unless you need to deal with bags or other defects. And then it is often good to give it a fresh flash coat after the corrections are made.
Then 2-3 full wet coats of clear, which then get the 4-6-12-buff treatment. (and again, black gets extra steps).
After buffing, I used 3M imperial hand glaze and rubbed that out. Then a hard carnauba car wax (I like one-grand blitz wax).
Have fun!
EDIT> I forgot to mention: I add a drop of dish soap to the sanding water, which I had in a pie tin. I always let the paper soak for a while to get nice and soft before I begin sanding too, as a "hard" sheet can cut grooves.
Also metallic colors always are two-step.
And final;ly, if doing a stain, apply two coats of clear over the sanding sealer, then tint clear for your "stain" and apply that, then finally seal with straight clear. This avoids blotchiness due to uneven absorption into the wood, and if the color is wrong: (too light/dark, wrong shade etc.) it is fully reversible.