A smooth coat of paint

[Jedi Lawja]

I've run in to this problem a number of times, perhaps someone has a good solution.

PROBLEM: I'm doing a build-up. Simple, few holes, sand, prime, putty, sand, prime, topcoat. Now, the problem I'm getting occurs on an area that I've puttied and sanded over. What's happening is I sometimes over-sand, sanding off a layer of primer. These areas look like paint chip indentations after the final coat has been applied. At this point it's back to putty and sand to make the area flat again. What exactly am I doing wrong here and how can I avoid it in the future?

Thanks,

Jay

 

[temponaut]

I'd love to hear some suggestions about this, too. I've always ended up either stripping the surface bare and starting again from scratch or living with the uneven finish.

There must be a better way...

 

[Gigatron]

After you're satisfied that everything is smooth (all holes filled) and primed, your final sanding should be wet sanding. You can get either specially designed wet sand sandpaper or 2000+ grit sandpaper. Sand the item while holding it under running water (keeps paint from building up in the sandpaper). It should come out almost glass smooth. And you should also do wet sands inbetween topcoats (depending on the paint of course).

-Fred

 

[temponaut]

Originally posted by Gigatron@Jan 13 2006, 10:17 PM
Sand the item while holding it under running water (keeps paint from building up in the sandpaper).  It should come out almost glass smooth. 
-Fred

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I do wet sand, but had simply been dabbing water periodically on the sanding surface or the sandpaper itself. And, yes, paint builds up on the sandpaper. This is the first time I've ever been advised to wet sand under running water.

Great tip, Gigatron. Thanks. :thumbsup

 

[Sidewinder]

Part of it could also be you have materials with a different hardness i.e. wear resistance - so when you sand the area, the softer (e.g. resin) material is more easily removed than the hard (e.g. putty).

SAS

 

[Jedi Lawja]

MM. I do wetsand, but I've never used anything finer than 600. This is also the first time I've heard of sanding under running water. Very interesting. I just sprayed the first layer of topcoat on my COP. I'll hit ACE and get some super-fine wet/dry sandpaper and see how it goes.

Thanks for the advice.

Jay

 

[Luke Skyvader]

Originally posted by Gigatron@Jan 13 2006, 01:17 PM
Sand the item while holding it under running water (keeps paint from building up in the sandpaper).  It should come out almost glass smooth.  And you should also do wet sands inbetween topcoats (depending on the paint of course).

-Fred

If you don't have a sink that's appropriate, i.e. we don't have a slop sink, my wife hates it when I use one of our bathroom sinks & I would never use a food prep sink (kitchen), try this. Get a large bucket. Fill it with water and dunk your paper in every so often & swish it around to unclog it. I also keep a spray bottle on hand to spray the piece (I'm working in a garage so I don't care about the mess too much). Think of the water as something thats lifting & carrying away the dust that will clog your paper. A little dishsoap, a couple of drops, in the water might work better.

Pete