Painting wood furniture for an even, durable finish.

April 24, 2009 4:56 PM

I'm going to be making this Parsons side table of poplar and MDF soon (Popular Mechanics link). How can I get the painted finish like the one in the picture?

The top is MDF and the rest is a series of 3/4" thick lengths of poplar. I like how the one pictured on the linked page looks so monolithic with a very even and slightly glossy finish. I've gathered from a few web pages that I should use several coats of an oil-based primer, especially along the edges of the MDF, and several coats of an oil-based paint. Oil-based products apparently level out better. Yes or no? A few more specific questions:

1. What sandpaper grit should I use between coats?
2. What level of gloss/type of paint should I use? I leaning towards semi-gloss.
3. What about some sort of clear coat protectant finish? Polyurethane? Would that make it more durable, which would be helpful since this will be living room furniture?

Tips, tricks, critique, advice would be much appreciated!

posted by jroybal to home & garden (10 comments total)

Proper surface preparation before you put a drop of paint anywhere will determine much of your final finish. Sand, fill joints or joinery marks, sand again. (Raw MDF edges should be completely filled with wood filler and sanded smooth too.) Since you're painting, sanding to 180 or 220 will be fine. You really need only one or two good coats of primer. Oil based will flow out well (i.e. no brush lines), but is stinky and harder to clean up. The new water-based coatings will provide equally good coverage and flow-out - just don't buy cheap primer or paint. A glossy paint will hold up better, but if you're topcoating, it doesn't much matter. A poly topcoat will indeed provide more protection if it's going to have drinks and whatnot set on it. Do a test with your paint to see how it affects the color - some polys have yellowing properties. I really like General Finishes High-Performance water-based poly. It brushes on smoothly and dries pretty quickly for re-coating.
posted by killy willy at 5:15 PM on April 24

what's pictured doesn't looks like it has a semi-gloss or gloss finish and wrt the previous response, a glossy finish will show up imperfections more.

again, if you want it to look really good, you will be sanding and filling until you're sick of it. i would do some test finishes on mdf/poplar scraps to get a sense of how it will look before...

i don't like dealing with the oil-based stuff. what i've found to work nicely is water based poly over flat paint. though, if you do you water based stuff it will raise grain etc so more sanding and prepping.
posted by geos at 5:51 PM on April 24

A friend of mine who makes his living painting tells me that the key to a brush-stroke-free finish is to use oil paint. He says that latex dries so fast, especially the newer paints, that it's impossible to avoid brush strokes. He says the other secret is to get it the right consistency. He thins it with....I forget...! Maybe someone else can fill in this part? Google? (sorry to drop the ball just when I seemed to have it well in hand!)
posted by sparrowdance at 6:24 PM on April 24

Most of the people I know who use paint on MDF use drywall joint compound on the edges to fill the endgrain. supposedly it is slightly more effective at filling in that paint-hungry porous edge than wood filler. since I laminate with formica type stuff, it's never been a consideration for me. definitely go for a poly finish for durability. primer will almost be more important than the paint for final results. good luck! nothing better than saying "yeah, I did that" after a compliment on your furniture
posted by Redhush at 7:45 PM on April 24

This Zinsser primer and their 123 Primer are really good - provide an excellent base, especially on wood/MDF.
posted by barnone at 8:00 PM on April 24

For a look like that, DO NOT use any poplar (or boards of any other species). Solid wood will expand and contract and open up visible seams before long, no matter how nice a job you do of it at first. Poplar will move more and cause problems sooner than most big-box variety woods. I know, it's cheap and smooth. But don't use it.

Instead, make the whole thing from MDF, securely glued in addition to whatever fasteners you use. Use yellow glue, not white; the yellow is less likely to swell on contact with solvent-based paints.

Fill any gaps or holes with something like bondo. Bathe the table in a sandable, high-solids primer and then block-sand all surfaces smooth and flat. If you sand through the primer, recoat and sand again until the whole thing is covered in flat, sanded primer without any MDF showing. Finally, spray paint it.

Simple as the table looks, this is a pretty demanding finish to create. I'd expect the finishing to be at least as time-consuming than the construction.
posted by jon1270 at 3:44 AM on April 25

When I redo a piece using oil based varnish (which I like better as it's self levelling), I finish with a rub down with rotten stone or car buffing compound, then rub the piece down with a plain piece of brown paper. Sounds like it wouldn't do much, but you can feel the difference the brown paper makes when you run your hand over the piece. Don't know if this would work using water based varnish. Agreed that finishing this piece is a challenge due to it's utter simplicity.
posted by x46 at 9:09 AM on April 25

My knowledge of these things tends to be theoretical (I read about making furniture, but I haven't made very much of it myself), but my guess would be that the finnish is sprayed on. I'm sure it's possible to get those kind of results with brushes and rubbing, but it would take far longer.

Also don't discount the art of the photographer -- a stylish shot with all those shadows highlighting the geometry of the piece, but only showing the flawless detail of one side, who knows what imperfections lurk in the shadows.
posted by Quinbus Flestrin at 9:43 AM on April 25

I agree that the finish looks sprayed on.

Sanding before applying a finish I like to run from 100 to 150 to 220 grits. After the first coat of primer, I smooth things out with 150 grit using a random orbital sander. After a second coat I go lightly with 220 or 320 grit and hand sand only. Towards the end, I might use 000 or 0000 grit steel wool.

I'd make a change to the plans on this table and reduce the number of joints by cutting each side from a sheet of MDF. One U-shaped piece per face. No need for separate leg and apron pieces on the outside faces. Cuts down on sanding and wood filler in joints.

This table is going to be pretty heavy with all the 3/4 MDF.
posted by birdwatcher at 11:55 AM on April 25

I've done a lot of painting -- you're right to be asking for tips, because even experienced pros knock themselves out to conceal joint lines. (Wood grain isn't as hard to hide, once you know which products to use.)

I use 220 for final sanding of the wood. Wrap the sandpaper around a small piece of scrap wood (about 4 x 1.5 x 3/4"), or buy a sanding block. The block lets you sand more evenly, with even wear on the sand paper. For a parson's table you might be tempted to leave sharpish edges, but you must round them off enough to accept and hold onto paint. A sharp edge is very easily damaged.

For filling, I'd use Bondo or other 2-part autobody filler. Mix it on something disposable like a piece of cardboard. If you want a slower drying time, use less of the hardener (the one in the tube). Try not to leave much excess on the surface, because it's difficult to sand. Bondo has a terrible smell, by the way.

The primer I like for this kind of work is the oil-based Benjamin Moore Enamel Underbody. It builds and sands very easily-- that is, you can apply two generous coats to fill grain and joint lines, and sand it really smooth. It takes longer to dry than other primers, but it's makes your job so much easier. Be sure to prime or seal the ends of the legs and the underside of the table to prevent warping due to humidity changes.

Use a high-quality, natural bristle brush brush like a Corona with soft black bristles. If there are a couple of bristles that are slightly longer than the others, carefully trim those because they'll leave faint lines in your primer or paint. Often, a thin coat of primer is used to seal the surface and improve adhesion. In this situation, though, you want to lay on a good opaque coat each time. I don't sand between coats with this primer. Apply it, spread it evenly, and then tip off, lightly dragging just the tips of your bristles.

When the primer is completely dry, sand with a block and 220 paper. There will be a huge amount of dust. At the end, you can go to 320 if you're obsessive :-)

If you don't want to spray it, use your good brush with oil-based paint for its dry time, durability and good leveling. I add Penetrol to the paint to help it lay really smooth and flat; sometimes I add a little thinner as well. Don't be stingy with the paint -- when you tip off, you should be smoothing just the paint without touching the underlying surface. I'd put the parson's table, upside down, on another table. Put some blocks or soup cans underneath so you can paint all the way to the edges. Sand between coats with 220 or finer to remove little blips and degloss the surface.

About a week after you finish painting, rub the surface with a piece of a brown paper grocery bag. It's just abrasive enough to make the surface feel satiny to the touch. The new paint will lose a lot of its sheen in the first 3 weeks, so don't worry if it looks too shiny.
posted by wryly at 12:48 PM on April 25