Anyone ever spray with automotive paint? (1 Viewer)

[Nick Hallett]

Has anyone here ever finished a unit by spraying automotive paint? I ask because I've never used the stuff before and it looks like it might be a hassle dealing with all the different things one needs to mix into the paint (reducer, retarder, etc...). I've only used my HVLP gun to spray latex housepaints before. The results were pretty good, but it seems impossible to eliminate the orange peeling that goes with the properties of latex.

I'm in the process of designing a computer sub with a Koda 8 and the 70W PE amp. All those damn chopper shows on the discovery channel make me want to try automotive paint for a finish.

How about some House of Kolor candy red with some metal flake mixed in, or ghost flames and pinstripes!

Hmm...on another subject, Don't ya think the SVS guys would make a great "reality build" show on discovery? I can see it now: "American Subwoofer" hell yeah!

 

[Wayne A. Pflughaupt]

Nick,

As you may already know, good automotive paint is very expensive – often between $60-100/gal.

Trust me, you won’t eliminate orange peel simply by shooting auto paint. The only way they get that “clear as water” finish you see on show cars is by careful and extensive hand-sanding between every coat.

Perhaps someone with more experience and knowledge of different kinds of paint can comment, but I see no reason why you couldn’t apply the same techniques the auto show painters use to household latex:

Between coats, apply automotive rubbing compound or sand with #400 paper, followed with #600 or perhaps #800.

For final coat as above, finished off with automotive polishing compound or sanding with #1200.

You might want to pick up a handbook on automotive painting at your local auto parts store for more (and probably better) information.

The only caveat might be the amount of time needed for the paint to cure before sanding. Based on my admittedly limited experience doing simple touch-up paint on cars and painting the interior of my house, house paint needs much more time to fully cure. You can paint a second coat after a few hours, but it’s still fairly soft. I don’t think you’d want to do any sanding for at least a week or two. I imagine if you contact the customer service department of the paint brand you’re using they could give you some information on curing times, etc.

Regards,
Wayne A. Pflughaupt

 

[Nick Hallett]

Yeah, I know about the price (I was kidding about HoK...), and the sand/paint/sand ad infinitum ritual, I just need to get away from the latex because the cure time to allow for good sanding does not exactly make sanding feasable. Also, the leveling properties of latex are rather poor compared to oil bases.

 

[John E Janowitz]

Automotive paint can work well. With painting any MDF enclosure, the key is preparation. The biggest issue is that the ends of the MDF like to keep soaking up paint, where the flat surfaces don't as much. The problem we always have is that that ends soak up so much that they expand. This means you always see the seam between pieces. The yellow acrylic urethane auto primers just didn't seem to help with this.

There are a few things we found to help. The first method is to coat the seams with MarGlass. This is the body filler with the very short fiberglass in it. The long hair stuff won't spread right. I cover the entire end of the enclosure like frosting a cake. then when sanding, get it nice and flat, but make sure to actually leave a thin coat over the entire end. Then you can use any automotive primer, then basecoat, clearcoat. I'd stay away from a single stage because it doesn't wetsand and buff like a clearcoat.

The second method I use is to primer with a catalyzed polyurethane. I use a Sayerlack TU20 basecoat. This is clear, intended as a sanding sealer on wood, but works great to seal up MDF. A couple coats and its all sealed but doesn't expand as much as with the yellow auto primers. This stuff is a 2:1 mix ratio. I pay about $30 a gallon for the Tu20 and $25 for a 2.5L can or catalyst.

I've found the TU20 and the Sayerlack topcoat to be ideal in most cases. I will often spray the TU20 over the Marglass. Then sand to a 320. Spray a basecoat of the color needed. Then spray a couple coats of the topcoat. It sands and buffs beautifully. The only way to get a really perfect finish is to do a wetsand and buff. I do a light sanding with a 600, then with a 1500. Followed up by a fast cutting 3M buffing compound and a 3M swirl mark remover. You can get it to look like glass.

In an ideal world you would be able to spray your clear on and it would lay down perfect without the need to wetsand and buff. Unless you have a prefectly dust free environment though it won't happen that way.

John

 

[Nick Hallett]

Yeah, I learned recently that bondo beats the hell out of regular wood filler, and I coat the entire enclosure with a thin layer (thick on the seams)to help seal it up before priming.

 

[Travis_R]

try to find a place in your area that is an Automotive Paint store, you could probably call a body shop and find one if not in the phone book, 90% of automotive paint retailers will can any automotive paint you want, there is a place near me that will make any can of spray paint for ten bucks, even house of kolor, I got 2000 Chevy Corvette Yellow for 10 bucks a can, only downfall is they cant can up the clear coat cuz it would be a can full of jelly by the time you got home, however, I just used laquer clear from auto zone on this paint and it looked great, actually painted a motorcycle with it and you cant tell the difference.

 

[Michael Hartwig]

I've had great success with Benjamin Moore's Impervo enamel. I brush and finish roll with a sponge roller (using a very light touch). I sand in between coats to flatten the paint. If you do about 6 coats or more, you end up with a pretty smooth and sexy feeling finish. The only problems are the dust nibs. A final color sanding and waxing would solve this. Or a very clean painting enviroment.