Medium Density Fiberboard, or MDF, is a composite, wood and chemical manufactured wood product. It is produced in sheet goods, typically 4-by-8 feet, and preformed paint-grade mouldings. Many pieces of manufactured furniture are created using MDF for the panel and detail elements. It is highly consistent in quality and can be purchased from your local lumber yard as a raw MDF sheet or covered with wood-grain veneer or white melamine liner. For building furniture, MDF is smoother and more consistent than plywood and cheaper than most hardwoods.
Choose or create a plan for your furniture. It is best to draw or purchase a scale drawing that can be referred to during construction. This will help in determining the size, material and number of parts to be cut for your project. Remember MDF is heavier than other sheet goods, such as plywood, and requires additional support under long or load-baring pieces. Use the plan to create a detailed cut ticket, or list of pieces that need to be cut out to complete the project.
Cut out your pieces following the list from your plans. MDF cuts much the same as plywood or softer hardwoods. Cut the largest pieces first. Make all cuts for multiple identical pieces, such as legs or drawer fronts, at one time. This will help to minimise setting up tools multiple times and save time and confusion. If more than one tool is needed, such as a table saw and a jigsaw, complete the process with one tool on all pieces before making the switch.
Rout and do other machining, such as drilling holes for door, shelf or drawer hardware after cutting pieces but before assembly. Sand each piece before assembly to be sure you have an equally smooth surface all the way to the edge. This makes for a more even finish.
Assemble your pieces with wood glue and finish nails or screws. The glue will form the strongest bond and the fasteners are there to hold it in place as the glue hardens. MDF can flake and split, so pre-drill pilot holes for all screws and keep nails to the centre of the edges.
Sand the piece down again once assembly is complete. If you are using veneered MDF, be gentle; the veneer is typically 1/16-inch thick, and you can sand all the way through, exposing the raw MDF beneath.
Prime projects that are to be painted before applying paint; MDF soaks up paint and primer, so be prepared for extra coats for a good finish. Use at least three coats of paint, semigloss and gloss work best, to get a smooth finish. Apply paint with a roller or sprayer.
Apply stains to veneered MDF with a high quality real bristle brush or airless sprayer. Unlike hardwoods, excess stain cannot typically be rubbed off or bleached to lighten it due to the fragile nature of veneer, so choose your colour carefully and spread it as evenly as possible. Add at least two coats of a lacquer-based finish; MDF is fairly soft and needs the extra armour for long-lasting good looks.