MDF, Multiple Density Fiberboard, is a lumber product composed of waste wood particles combined with an adhesive and pressed into sheets. The resulting wood is perfectly flat and smooth and it lends itself to a wide variety of furniture, cabinet, and utility uses. The faces of the MDF sheet need little or no sanding before accepting a finish but the edges show the composite nature of the material and require different treatments to provide an acceptable finish.
Solid Wood Edging
The edging of choice is solid wood if the MDF sheet has been veneered or used in a fine furniture or cabinetry project. Strips or sticks of a matching wood are cut from solid lumber and glued or tacked to the edges. The solid wood blends in with the veneer when finished and masks the MDF core from view. If the edges will be exposed to a lot of handling, a dado or rebate can be formed in the MDF giving the edging additional surface area for bonding.
PVC or Plastic Edging
MDF used for table tops or other interior surfaces exposes the edges to a lot of abuse and the granular nature of the material makes it highly susceptible to chipping. PVC or plastic edging material is useful in these applications as a protective barrier. It is applied with adhesive around the perimeter of the piece and a thin dado can also be cut to aid in aligning and gripping the edging material.
Veneer Edge Banding
Similar to solid wood edging, very thin veneer strips of solid wood are manufactured for finishing the edges of MDF. The face of the veneer edging is pre-sanded and the backing has a heat activated adhesive already applied. To apply the product, the woodworker uses a household iron set to its highest temperature and then simply aligns the banding and irons it on to the core. When the adhesive has set, the edges are trimmed with a razor saw or simply sanded to match the thickness of the MDF core. The veneer finishes just like solid wood but is more susceptible to damage than strips or sticks.
Filler and Painted Edging
If the appearance of the edges of an MDF piece are not important or will not be seen, they can be painted to match the surface of the sheet. The grains of the material will remain visible through the paint and will not have the smooth finish of the faces but a variety of sealing techniques can be used to minimise this problem. Automotive body filler is often used on MDF edges to create a smooth finish to match the face surfaces because it adheres well to the material and sands well.