Disclaimer: I don’t have any pictures for this, because I don’t have any current projects going that are super relevant. Rather, my advice here is based on all my (other) years of experience. We’ve talked a lot about making MDF look like stone but…what if you want to make it look like wood?
The most important thing, as always, is prep. Start by lightly sanding your piece. I really like sanding sponges (i.e. my good old Norton 400’s, or whatever works for you) for this, as they’re great for following curves. And, as always, start low and go slow. You can always take more off, but it’s hard to put back!
Sanding, too, leaves a mark so this is a great time to start thinking about grain. What direction is yours? You’re not trying to create grain–don’t push too hard–but, rather, a situation where graining is possible. In other words, if your grain is going up and down don’t sabotage yourself by sanding from side to side.
Next comes…sealing! MDF is porous, which means it’ll suck up your eventual paints–and every oil, dirt, and other gross thing in the environment–unless and until you seal it. Start with a high quality water based varnish like Liquitex. I generally start with one allover coat, then an extra coat on any exposed edges. Just like with wood, the raw edges on a piece of MDF are going to be extra porous.
Once your piece is completely dry, lightly sand it smooth. You might, at this point, want to do another coat (and then sand again). At this point, you want to spray your piece with an enamel based sealant. Why? Because, going forward, you’ll be using WATER BASED PAINT. And, well, you know what they say: oil and water don’t mix. We want a base, now, for your artistic masterpiece, that won’t be degraded by our brushwork.
You may have noticed, I’m using clear products here. Why? Well, MDF already kind of looks like wood so–again!–there’s no point in working against ourselves. For a sealant, I recommend Mr. Super Clear (from the Mr. Hobby line), or Krylon. Both are high quality and, along with the AK Interactive line of spray sealants, the only kinds I personally use. Either way, get matte!
Wait until your environment’s humidity is under 50%, if possible, to spray. If you’re unsure, remember: you can check your phone! Mask up, place your piece somewhere–outside!–sunny and dry and CLEAN, such as on a paper plate on your driveway, and lightly spray your piece. You can do a second coat after about 15 minutes. Then, wait at least four hours before flipping your piece over and spraying it again.
Now, you’re ready to paint!
As far as graining, I have a tutorial here. That’s on a Chrysnbon piece, but the principle is the same. In my own work, I like to collect reference photos before I start. Just like it’s hard to paint a portrait without either a living model or a photograph, it’s hard to remember every detail of, say, a battle worn axe.
For products, I personally like the following sets:
Whatever paints you decide on, though, the name of the game is dilute, dilute. You’ll want to create your grain using washes, which means keeping your brush wet, stroking through your work to create a grain, then letting it dry. Then doing it again! I usually need at least six passes on a piece, before I feel like I’m seeing anything approaching a realistic wood grain. Remember, too, realism comes from subtlety. Real grain isn’t that colorful. It’s rare that I use more than one or maybe two colors, before I move on to next steps (like weathering, which can usually be accomplished with more paints from the same set, plus maybe a weathering pigment or two).
Once you’re done with your basic wood, and BEFORE you move on to next steps, wait until everything’s dry (at least 24 hours) and then lightly coat your piece to seal it. You can use the same spray you used before! Now…on tot glory!