MDF (medium density fibre)

[Jeff and Jennifer Cook]

I am planning on building a raised panel wainscoating in my dining room and am thinking on building the panels from mdf.

Has anyone had any experience on using this material on raised panels. If so can you help me out with any pro's or con's. Let me know Jeff

[Robatoy]

Pros? Dimensionally stable when finished, easy to machine, cheap. Readily available in accurate thicknesses.

Cons? Makes a lot of very fine dust, smaller than 5 micron in some cases. End grain tough to seal (making raised panels will give you lots of open grain). Can be sealed with thick latex primers. Hard on tools, because it is abrasive, taking the edge of carbide rather quickly which means it will start to leave burn marks.

Go for it. I have had pretty good success making raised panel doors from MDF. BTW, not all MDF is created equal.

0¿0

Rob

[Mike in Mystic]

MDF is a very good choice for this application. I'm assuming you'll be painting, and MDF provides a great substrate - flat and smooth and very stable. The one big caveat is to ensure you throughly seal the MDF from moisture, as water will cause it to bulge significantly. As for machining, it is easy to cut and rout, although it dulls blades and bits extremely fast and creates a TON of airborne dust/particles. Be sure to have a dust collector/air cleaner/dust mask (all 3) in use during machining. Finally, it is VERY heavy (about 100 lbs. for a full 4'x8' sheet). I just bought 8 sheets for a built-in project I'm doing and lugging the finished boxes up to the 3rd floor of my house is no fun. Get help if possible.

Mike

[loutent]

Hi Jeff,

I have used MDF (medium density fiberboard) for many raised panel projects that are to be painted. I have used it in painted cabinet doors as well as wainscoating in our stairs and hallway upstairs. Even for painted drawer fronts.

It is a very good material choice for the panels in that it takes paint well (although you will have a little sanding to do where the cutter shears the MDF). It is a little hard on the panel cutters and also makes a LOT of fine dust - be sure to wear a dust mask.

I generally use poplar for the rails/stiles and MDF for only the panel.

Lou

[Brian in Vancouver, BC]

Robatoy wrote in news: [e-mail]:

Rob;

I never thought of mdf as having "end grain". Care to rethink that statement? Seems to me all the surfaces are similar with a material like mdf. There is no grain, thus no "end grain".

Brian

[Mekon]

The edges definitely have a different 'character' than the large flat surfaces, if you have ever seen MDF that has been exposed to water the edges splay out as if the sheet is made of many smaller sheets and if the water soaks the flat areas it bubbles. If you trimmed a sheet so the cut-off was square in cross section, the original edge would be easy to spot. Sealing presents its own problems, although if done right, then it will stand up to lots of wear. I have two doors near one another, one is one that I got from a recycling depot a beautiful, heavy exterior door with lots of molding. The other appears to be identical, but all of the panels are made from MDF, it was a duplicate made to match the old door. So far (5 years after hanging) I have had to shave the old door once, but the MDF is as square and well fitting as the day it was made.

A whole floor of my house plus the mezzanine kitchen is lined with MDF panels (including the ceilings), it is very easy to cut, shape, fit and paint. I would have preferred to have done the lot with T&G hoop pine, but the budget didn't stretch that far. If any of you are interested I'll post pics in binaries.

Mekon

[Andy Dingley]

More like "edge grain". The surface is one thing, the edges are quite another. There's a difference between adjacent edges too, but only under a microscope.

Take a 3" square offcut and leave it outdoors for a couple of rainstorms. You'll soon notice that the centres of the faces are holding up pretty well, but the edges have expanded into soft strawboard that's a quarter thicker than before. Then they start to delaminate.

[JGS]

[max]

MDF is treated or processed with heat and pressure to "burnish" the surface, sort of like the crust on French bread.. When you cut it you expose the untreated part which is basically a sponge. When we use mdf as paint grade, our finisher wants us to mix white or yellow glue 50 50 with water and paint the cut edges. It will still need to be primed but it will then need only one coat. I have seen him use 3 or more coats of primer on an untreated edge. max

[Guess who]

It might have been a poor choice of words, but the physics of the end structure is still a lot different from that of the top/bottom. A screw will hold better driven in from the top than from the side, as it is with wood, even if still poorly held [**]. The material is

*layered* in that sense. Drive a chisel into the top, and into the side to see some difference of behaviour. Water swells the material as it would with any pressed product. [**] I got around that the one time I used MDF for a table top. Plunge-route [carefully] a 1" hole, and insert and glue a hardwood plug. Pre-drill, and screw into that. Worked just fine. The plug is easily routed down to the level of the MDF when set.

[Woody]

I've done it, and got pictures to prove it and discuss it at:

a year, it looks great. To see if MDF was a dent-resistent as poplar, I took a hammer and pounded each as hard as I could and MDF held up just fine.

Regarding the "end grain" discussion, this is an issue (as I note) with the milled edges, particularly with a latex (water based) primer. This raised the "grain" on the milled edges and took me about 3 days to sand out over the entire room.

I've also included some hints about how to size the panels as well as references to texts that contain additional examples/info.

You will get a *ton* of dust routing the panels and rails/stiles. Wear a dust mask and goggles. I don't (yet) have dust collection and my entire workshop was covered in a fine powder coating. In addition, the dust repeatedly clogged the electronic switch on my under-table Triton router (they've subsequently provided a shrouded switch) which required repeated disassembly and cleaning to get it working again.

The end results were terrific. I've mostly forgotten how hard the work was and am contemplating another room. Go for it

~Mark.

[loutent]

Hi Woody,

That is one nice looking job! You are a real craftsman.

I know what you mean about all the work involved.

My brother used a kit to do his. That is another approach for the OP.

Lou

[Jim K]