Medium density fiber board or MDF as it is commonly known is an engineered material that consists of wood fibers and glue. It has been available since the 1980’s.
It is one of those products where lumber companies had a waste product (wood fibers, saw dust and wood chips) and wanted to make something out of it that they could sell.
Like the old saying goes waste not, want not.
How is it made?
What would have been waste wood is shredded down into course wood fibers, in a similar process that is used in the paper industry for wood pulp. The wood fibers and glue are mixed together into a course slurry.
Some MDF has a waxy feel to it. Well, some manufactures add wax to the mix as well.
The slurry is assembled into a thick mat. It is heated and pressed to the desired thickness. The heating and pressing drives the moisture out and allows the glue to bond well with the wood fibers.
Why is so heavy, but not very strong?
That is because MDF is made from wood fibers and glue, so it is fairly dense, but its strength comes from the glue. Where as solid lumber’s strength is in the wood cells interlocking and the species of the tree.
Home builders and furniture makers love this stuff.
1) It is dimensionally stable it does not expand or shrink with changes in the relative humidity. But don’t get this stuff soaking wet it will cause the wood fibers to swell up and break down the glue.
2) It is less expensive than solid wood, so they save money
3) It takes paint very well. I have seen new home’s where the closet shelves are made MDF.
How does MDF compare to solid wood?
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MDF |
Solid Wood |
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Price |
Costs less per board foot |
Costs more per board foot |
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Strength |
Weaker than most solid wood species |
Stronger - Strength varies based on the species |
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Lengths |
Most commonly available in eight foot lengths. |
Varying lengths |
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Material Appearance |
Free of knots, grain deviations, splits, checks and other wood defects |
Depends highly on the quality of the tree and the species |
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Finishing |
Must be painted or covered with some sort of a laminate. A clear / stained finish looks awful. |
Can be stained and clear finished, painted or laminated applied. |
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Weight |
Heavier |
Not as heavy, higher strength to weight ratio |
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Water exposure |
Water exposure will cause the material to swell and warp. |
Will swell a little and can be dried out easily. |
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Fastening |
Very hard to edge screw. It can not be edge nailed, the MDF will split apart. It can be face screwed and nailed, but special care has to be taken. |
Takes nails and screws very well. |
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Often manufactured with adhesive containing formaldehyde. |
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Do you use MDF in your projects?
Personally I don’t like using it. The extra weight, difficulty to nail and lack of strength makes it a pain for me to work with. I prefer to work with solid wood and plywood for large areas.
