Everything today has an acronym, and they have become a part of the English lexicon in everyday use now. You probably use some of them, too, at the least when you are using a messaging app on your phone. LOL, LMAO, ROFLMAO, NSFW, and so many more. Raise your hand if this is true.
Key Points:
- MDF prep is essential but not onerous.
- There’s no grain, so if your project wants grain, it’s not a good choice. But, if grain is not important, you’ll save money by choosing it over natural wood.
- Give it a poly finish over the stain, and you’re done. Workbenches, kid’s playroom furniture, and, as you will see in the video at the end, even molding are all MDF-able, if that is a word.
In woodworking, we do the same. When building a deck, we use PT wood; QSRO when working with quarter-sawn red oak; RAS for our radial arm saw. Today’s topic deals with another acronym, MDF. We’ve used MDF in our shop, and one of the workbenches I have built for myself was made with MDF and some leftover 2 x 4s I had lying around.
It came together easily and quickly, and for a finish, I chose some leftover paste wax, and it worked well for me.
Today, though, we’re interested in the application of stain on MDF, and there are a few things you need to know and understand about it.
Medium-Density Fiberboard
The 3-letter acronym MDF stands for medium-density fiberboard, as you probably know, or at least guessed. It is a versatile composite material made from wood fibers and resin under intense pressure and heat to form sheets.
We say versatile because it can be used in workbenches (like we did), cabinets, and shelving. We even know of someone who used it for stair treads that led down to his shop in the basement, although we probably wouldn’t have chosen that material for them. It is not as strong as natural wood, but it is strong enough for many purposes.
MDF furniture is also a thing and can be a good and economical material for desktops for kids. MDF furniture will not have the beauty of wood grain on the desktop, but in a kid’s playroom, it can be a sensible choice.
This wood product cuts easily, is less expensive than real wood, and can be used in the making of furniture. A circular saw is more than adequate for cutting MDF wood, although your table saw will also easily break down larger sheets.
Your circular saw should have a cutting speed of around 3000 RPM (another acronym there) and ideally will have carbide tips on a 60-tooth blade for a clean cut. Something less will run the risk of crumbling, as MDF is made of softwood and hardwood shavings that can come apart with an inadequate blade and blade speed.
You will also want to be careful when screwing into MDF. It is, after all, wood shavings and fibers, and screws will tear into it roughly. Keep your screws a bit away from the edges and ends to avoid a tear out, and don’t drive the screws too hard or deep. This is especially true when using a wide-diameter screw, so keep than only wide enough to hold the MDF in place to avoid excess tearing.
When cutting MDF, you will want to wear some safety gear – face mask and safety glasses, at the least. Particulate of wood and resin in the composition of the MDF will be dangerous to inhale, and if you are doing a lot of cutting, those particulates will linger in the air for a while.
Some MDF products also have formaldehyde in their composition, and this is toxic to humans. It’s best to use a dust extraction system when cutting it, but even then, still, put a face mask and safety glasses on as an extra precaution.
Staining MDF
When staining MDF, and yes, you can stain it, there are a few extra steps to follow, especially if it has been previously stained. If you are changing the stain color on your MDF doors, for instance, the old stain must first be removed. If your project is new, though, and the MDF is virgin (no paint, stain, or finish of any kind), you will prep the surface as you would natural wood.
MDF is fiber and shavings, so it does not have the same wood grain as natural wood, so the finished look will be different. Additionally, MDF absorbs stain differently than natural wood, so you should expect to need multiple coats of stain to achieve your desired color.
If the MDF has been previously stained, you will need a wood stripper to remove it. However, MDF does not absorb stain deeply, so the removal process is easier than with real wood. It’s likely you will need only a light application of a wood stripper to remove the old finish.
As with the cutting of MDF, safety precautions should be taken when using a chemical wood stripper – gloves, face mask, and safety goggles.
After the wood surface has had a chance to adequately dry (check the label of the stripper you used), you can use 120-grit sandpaper to remove any lingering finish. You want it all gone before you begin to apply a new stain to avoid blotches. Again, remember that MDF does not take stain the same way natural wood does, whether you are using a liquid stain or especially if you are using a gel stain.
Surface prep, whether on virgin board or previously stained board, will also include filling any dings or dents with a wood filler or wood putty. You want a smooth surface to stain when the time comes. Wipe any dust from sanding off, and move to a 180-grit paper for the final sanding.
Again, make sure you clean the wood surface with a wet rag after that final sanding.
Applying Your Chosen Stain To MDF
When your board is fully prepped and ready, you’ll want to assemble your supplies, including:
- the wood stain – we recommend an oil-based stain
- a paintbrush or roller
- rags or sponges
- your drop cloth
- your safety gear – glasses, gloves, and face mask
The sanding will make the MDF more porous, but stain will not be absorbed deeply. You will want to apply a few thin coats of stain, giving adequate time for each to dry fully. The manufacturer’s suggestion on the can label will tell you how much time that will or should be.
A paintbrush (foam or bristle), a roller, a clean rag, or a sponge can be used to apply the stain, and after a moment, be sure to wipe all excess stain off.
We know that MDF has no grain, so the stain will simply add color to the surface rather than enhance any surface feature. Your task when sanding is simply to make sure the application appears to be even and uniform. Wiping excess stain will reduce the chance of a blotchy appearance, so pay attention to this.
How many coats of stain you apply will depend on the color you want to create; darker colors will likely require more coats, and lighter colors fewer.
A light touch is recommended when applying stain, whether with a paintbrush, a roller, a dry cloth, or a sponge. Remember, too, that an oil-based stain will require more drying time than a water-based stain, so show a bit of patience in accordance with the label instructions.
MDF Edges
The edges of MDF boards are open and very porous, just like plywood. You should expect a different depth of color and degree of stain absorption there. You might want to consider banding the edges of the boards just like we do with plywood.
Banding is made from real wood, also, and takes stains well and better than MDF. That will give you a more uniform color, although you will have the distinction between the no-surface feature of the MDF and the appearance of the banding.
We wrote a piece about edge banding plywood previously, so take a look if you have any questions about its use.
Finishing The Project
When the stained surface has fully dried, and you are happy with the color, you will want to apply a thin coat of polyurethane.
Usually, you might not want to use a water-based poly over an oil-based stain, but that’s because the water-based poly can raise the grain of the wood. Since MDF has no grain, there’s no risk of that. The poly will protect the stain and keep the MDF looking good even without grain.
One word of warning about applying the polyurethane: make sure the stain is absolutely dry. Read the label on the can, follow it, and then add another day to it to be extra sure.
As a little aside, MDF can also be painted. Follow the same process of surface prep, pick your color, and paint. You can use either an oil-based or water-based paint and plan on a couple of coats, especially for the edges where the paint will be absorbed more fully.
You will want an even coat over the entire MDF, face, and edges, and paint can give you that better than stain.
An Interesting Video About MDF, Staining, and Graining
We found an interesting video about staining and graining MDF, or at least giving the appearance of some grain and real wood. We all know how to stain wood, even with the little extra steps for MDF, so a video on staining alone would be superfluous and unnecessary.
This one, though, is different and involves the use of stain primer, stain, and whitening, and it’s pretty cool.
MDF has its place in a woodworking shop. As we said at the beginning, one of my workbenches is MDF and 2 x 4s, and it serves my purposes well on the cheap. Try it, and we’re sure you’ll find lots of uses for it.
