How to get smooth painted finish on MDF?

[cgallery]

I have done a significant number of speaker boxes earlier in my life, and I used those disposable rollers you purchase at the hardware store. They are the ones where the package they come in (wall-hung) becomes a tray that you can use for holding the paint (I never used them that way, though).

The roller itself has a very short knap. They are NOT foam rollers.

My technique was to drizzle some of the paint on the panel, then roll it out with the roller. I typically applied 2-4 coats, depending on the paint, with a coat of primer first. Don't overwork the paint, either.

I stored the rollers in plastic bags between coats so I could use a single roller on all the coats required for a single project, like an 8 cubic foot sub.

A very light sanding between coats is often necessary. I used one of those 3m pads (super-fine) that was nearly worn down to nothing.

I kept a sub that was finished like this at work and a woman that worked for me called B.S. when I said I had made it myself. "What," she asked, "it is made of metal." When I told her it was just painted wood she actually called my wife to see if I was pulling her leg.

[Bulkley]

I forgot to mention that it is manditory that the work be sanded between coats. After the prime coat use 220 grit. After each top coat use 400 grit or 600 grit. If you use previously used, or even worn out, emery paper, you will avoid sharp edges.

[gychang]

I have done a significant number of speaker boxes earlier in my life, and I used those disposable rollers you purchase at the hardware store. They are the ones where the package they come in (wall-hung) becomes a tray that you can use for holding the paint (I never used them that way, though).

The roller itself has a very short knap. They are NOT foam rollers.

My technique was to drizzle some of the paint on the panel, then roll it out with the roller. I typically applied 2-4 coats, depending on the paint, with a coat of primer first. Don't overwork the paint, either.

I stored the rollers in plastic bags between coats so I could use a single roller on all the coats required for a single project, like an 8 cubic foot sub.

A very light sanding between coats is often necessary. I used one of those 3m pads (super-fine) that was nearly worn down to nothing.

I kept a sub that was finished like this at work and a woman that worked for me called B.S. when I said I had made it myself. "What," she asked, "it is made of metal." When I told her it was just painted wood she actually called my wife to see if I was pulling her leg.

thanks for the great advise. gychang

[jlm]

Do you use Floetrol in the paint, or primer, or both?

I just use it in the paint. After priming, it's best to sand it lightly before the first coat of paint (then as others have suggested, sanding between paint coats isn't a bad idea, either). It's a bit more involved process than just slapping on a couple coats of paint, but the results are much nicer.

As others have pointed out before me, it doesn't make much sense to spend all that time building things and then skimp on the finish, whether it's paint, poly, oil, lacquer, or whatever.

Floetrol is available at Home Depot and Lowe's, it comes in quarts and gallons.

[sscherin]

I've done a bit of MDF painting..

Foam roller suck

first we roll on 1 coat of Killz water base primer to seal the uhhh "wood" with a standard roller
sand that smooth with 220
Then the color coat gets mixed with Floetrol. (get it Homedepot)
Don't go crazy if you are using gloss paint.. It will dull the finish.

The following color coats are brushed on.. the Floetrol smooths out the brush marks.

You can also roll it with a short nap roller.

[docrowan]

I've tried foam rollers with no succes. Looks like a retarded monkey painted.

LOL!!

That's the way most of my paint and finish jobs turn out. I never had such a pithy way to describe it before, though.

[gychang]

I've done a bit of MDF painting..

first we roll on 1 coat of Killz water base primer to seal the uhhh "wood" with a standard roller
sand that smooth with 220
Then the color coat gets mixed with Floetrol. (get it Homedepot)
Don't go crazy if you are using gloss paint.. It will dull the finish.

The following color coats are brushed on.. the Floetrol smooths out the brush marks.

I plan to use the above technique with modifications.

1. use the roller to get one light coat and Kilz primer then sand with 220 and repeat with the 2nd coat.
2. latex color with Floetrol added, will try the brush or foam brush (will test on the scrap) 3 light coats with sanding in between.

I hope this will work, thanks,

gychang