Sanding Grits question

[PatG]

Apologies in advance for the repeat on this question. On my bare metal and filler, I'm using a coat of epoxy and then two or three coats of 2K primer. Will sand that with 180 grit dry (blocked with guide coat). At that point, I was planning to seal with one coat of reduced epoxy and paint with two coats (probably) of solid color (non mettalic) DBU and follow with Univ. Clear. Do I need to follow the 180 dry with 400 dry, before I seal and apply base coat or will the epoxy sealer fill 180 grit sand scratches?

Second question is do you guys do all of this sanding by hand? I have a short throw palm sander that I use for color sanding - don't know if that would be useful for sanding the 2K or if I should stick with durablocks and elbow grease.

Thanks for any tips.

Pat

 

[strum456]

You will need to sand to 320 or 400 before sealer. Some use a da with a soft interface pad as a final step before sear to give a more uniform surface. I would atleast go to 320 by hand though.

The da can speed the process for clear sanding and some have a lot of success with them. I have not figured out a process that works well for the da so I usually end up sanding the clear by hand up to 2000 and the I use trizact 3000 pads on the da before buffing.

 

[Benny]

You will need to sand to 320 or 400 before sealer. Some use a da with a soft interface pad as a final step before sear to give a more uniform surface. I would atleast go to 320 by hand though.

So blocking your 2k with 150, then hand sanding with 320 to get the scratches out would give acceptable results? I had been under the impression the you effectively had to block the panel several times with finer and finer grits to get to where you need to be for sealer.

Even though they are pretty fine, couldn't hand sanding with 320 or 400 still leave your surface fairly uneven?

Thanks

 

[jcclark]

The finer grits like 400 only smooth the surface, they won't straighten or flatten
like a coarse grit.