Can You Varnish MDF? [SOLVED]

Medium-density fibreboard (MDF) is a wood composite similar to plywood. It's often sealed with a wax and resin binder and formed into panels with a combination of high heat and pressure. MDF is generally tougher and denser than plywood, making it popular for various tasks that need a strong, light wood substitute. If you've used MDF recently and want to make it look a bit nicer, you're likely left with a question. Can you varnish MDF? Luckily, we've got you covered.

Can you varnish MDF? Yes, but it will have a different final finish than standard hardwood might.

There are a few important things to take note of, so keep reading to make sure your project turns out perfectly.

Can You Varnish MDF, and Why Would You?

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So the first question, whether or not you can varnish MDF is simple. You absolutely can, it's just going to turn out a bit different than a different "standard" wood might. This is because it doesn't have a grain like, for example, oak would.

The second question, why varnish MDF, is also rather apparent - because it looks nice! But because it doesn't have a grain, you're likely to end up with a slightly different look than you may be thinking of. If you're curious what a varnished MDF board looks like, click here . This video explains what type of stain or varnish to use on MDF (which we'll get to) and will give you an idea of what it looks like.

Varnishing a piece of MDF that has sustained weather damage is actually a really good thing to breathe new life into it. The one caveat to this is that you shouldn't varnish damaged MDF if it's load-bearing (which it really shouldn't be, but that's a whole other article). You don't want to trap moisture into something that's holding weight.

Now that we've got that out of the way, let's talk details, shall we?

Choosing Varnish and Stain for MDF

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Your first stop when choosing a varnish should always be a local paint or hardware store. This is because you'll be able to get a better idea of the finished product than you will from an Amazon thumbnail. You can use just about any type of stain on MDF, from maple or oak to jarrah. You're looking for:

• Gloss or semi-gloss varnish are the most common ones available.Choose a gloss level and colour that you like!
• Look for solvent-based varnish. This will result in a better colour coverage than other varnishes.
• If the MDF will be outside, pick a weather-resistant varnish. If you don't, you'll find yourself here again in a year or two, redoing your varnish.

Putting Stain & Varnish on MDF

First things first, prepare your area. This is pretty much the same as painting, in that you'll want to lay down newspaper or plastic sheeting to catch stray drips. Choose a well-ventilated area to apply your varnish, as it releases fumes similar to paint that are... not ideal to inhale.

If you have old paint or a stain on your MDF, you will need to remove it first. It's not super hard to do, as MDF doesn't generally absorb paint or stains very well. You can apply wood stripper to remove old paint and stain or sand it until it's entirely gone. While I recommend the former, the latter works just as well, with just a bit more elbow grease put in. Be sure to allow the surface to dry fully if you use wood stripper, as you don't want to paint over it!

Now, onto the fun part!

The Process

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1. Sand all surfaces of the MDF that you plan to varnish and stain, including the corners and edge faces. Use fine-grit sandpaper, going finer if you plan to use a high-gloss varnish. This will help it to stick and help keep that smooth, silky finish.
   • Brush the surface once you’re done with a soft rag to ensure it’s entirely dust-free. Dust can interfere with the stain and varnish sticking, and will result in a less-than-ideal finish.
2. Apply the stain in long, thick, even strokes with a paintbrush. Be sure to go back over any drips or streaks to get an even layer.
   • If you want to mimic the wood grain look, you can alternate horizontal and vertical strokes. Use a smaller brush to get to smaller, more detailed areas.
3. Repeat this process 2-3 times, minimum. You’ll need to allow the stain to dry fully before going again. You may need more layers if you notice it soaking into your MDF.
4. Repeat steps 2 and 3 with your varnish. Be sure to use smooth, long strokes to ensure an even coat. You should need no more than two coats, and will need to allow it to dry in between coats.
   • Lightly sand your varnish in between coats to ensure a smooth coat.
5. Wash your brushes immediately. If you don’t, they’ll stick together and you’ll have a dedicated varnish brush.

Final Thoughts

Varnishing MDF isn't too dissimilar from painting. It's (generally) the same process, but it'll come out looking drastically different from a paint coat. If you're a fan of the hardwood look, but don't want to spend the cash on a true hardwood piece of furniture, varnish is a great choice. You can even mimic wood grain by using a stain and varnish in tandem by alternating the direction in which you brush it.

Just be sure to choose the right varnish for the job. If it's going to be outside, you need weather-resistant varnish. If you opt for standard varnish, you'll find yourself back here again in a year or two, kicking yourself for not listening to me. Once you've chosen the gloss and colour level of your varnish, simply sand the MDF and apply your stain. You can go back over the stain with varnish, sanding in between layers until you get the final look you want.