finishing a paint job...

[Rob Cork]

I'm not very good at short posts, so if this starts to ramble I apologise...

I've just applied the last coat of paint to my case, and don't want to screw it up when sanding it smooth. The finest sandpaper I have is 1200 grit, but that still seems to leave slight scratches on the paint when I've used it before on earlier coats. I'm thinking of just going straight to the polish stage - we have something called 'Mer' for polishing cars, and I'm using automotive paint, so it ought to be fine. The only thing is although the finish looks smooth, it feels grainy to the touch, so I think I ought to sand it first... which is what I really need to know about.

What grit to use for the finishing touch? Presumably it should be wet sanded, I've never done that before, is it just dampening the surface and then sanding away?

One last thing, it says on the instructions on the spray can to leave the final coat to dry completely before applying any finishes - and it suggests 7 days for it to completely dry. I was wondering whether 2 days would be enough? I'm just too impatient... :D

[CrystalMethod]

Did you sand in between coats? The object is to sand till the surface is completely smooth (or as smooth as you can get it). Wet sanding is hard to explain how to do properly. It almost feels as though you aren't even sanding anything. Best way to do (for something this size) it is to get a large sponge, and a bucket of water. Start with 800 Grit wet/dry (obviously) and moving your way up through the grades (I stopped at 1600 grit), squeeze out the water from the sponge as you sand in circular motions. When you start to feel the sand paper "catching", squeeze out some more water. if you've done it right, the paint when it's dry (free of water), will look completely flat (as if the color you painted it was a flat color). Next step is to go over the paint with a rubbing compound (I used "turtle wax" paste form rubbing compound). This takes a LOT of elbow grease, but the results are awesome. I went one step further by using 3M "Finishing compound", with my buffer (I was an auto detailer for a while), but you can do this by hand as well. I then sprayed on my clearcoats, and buffed again. unfortunately, when I had the cover to my case laying on the top, while doing the sides, the imprint from the towel I was using to keep from scratching my nice new paint job was left on it. This is the problem with using automotive paint, it takes WEEKS without an oven to cure properly. I may have to re-paint to get rid of the marks, but if I can borrow my Bro's digital cam, it'd make a really interesting article....
....Hmmm... I wonder if I should....

[Rob Cork]

Cheers for the advice - yeah I have been sanding in between coats, just dry sanding with 1200 grit. I always made sure it felt nice and smooth before applying the next coat, and I've built up a nice solid coat now to work with. I'll just pop down to the hardware store and stock up on sandpaper :)

[OpenFriday]

Hey Rob what kind of paint did you use? Im off to pick up some automotive paint of some sort in a minute. Did you prime the case? I used automotive primer as thats what i was told to do and that should work well with automotive paint. (I assume).....handsanding you crazy bugger. Cool avtar btw.

-OF

[Oni]

Rob, try to find 2000 grit wet/dry, and then wet sand it w/ some warm soapy water.

[Rob Cork]

I'll have to get the finest grade sandpaper I can find - 1200 just ain't gonna cut it. I've got it pretty smooth now, but the finish is still kinda blotchy - I'll put another coat on just to get it absolutely smooth... :)

Yep, automotive primer OpenFriday - used two coats, sanded after the first and then sanded even more carefully after the second to get a nice smooth base for the colour coat. I've just done the first coat on the front plastic bezel, and although I'm using automotive paint I didn't sand it first at all (it was pretty smooth as it was plastic) or use any primer - but it looks damn nice after just one coat! I'll put one more on for the sake of it, but it looks as though the plastic is much easier to paint than the metal - which is a relief!

On a side note, just waiting for the doorbell to ring letting me know my KG7-RAID has arrived - ought to be delivered today :D