Interior design : What is MDF-Medium Density Fiberboard. ?
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MDF belongs to the hardboard family of products which are made from wood fibers glued under heat and pressure. Medium Density Fiberboard typically has densities between 33 and 50 pounds per cubic feet while High Density Fiberboard (HDF) ranges between 50 and 80 pounds per cubic feet.
Medium Density Fibreboard (MDF) is an engineered wood-based sheet material made by bonding together wood fibres with a synthetic resin adhesive. MDF is extremely versatile and can be machined and finished to a high standard. As a result, MDF has replaced solid timber as a low-cost alternative in a wide range of applications across industry.
The majority of MDF is mainly composed of softwood, although some brands may contain a higher percentage of temperate hardwood if this is locally available to the manufacturer. High levels of hardwood can be found in MDF board from outside the UK and Ireland.
The most common binder for boards intended for dry environments is urea-formaldehyde. Other binders may be used depending on the grade of board and its intended end-use. For example, melamine urea-formaldehyde, phenolic resins and polymeric diphenylmethane diisocyanate (PMDI) are generally used in boards that require an improved moisture resistance. PMDI binder is not formaldehyde-based and consequently does not emit any formaldehyde. The exact constituents of an MDF board will vary from product to product.Q: What properties does MDF exhibit?
A: MDF has many qualities that make it an ideal replacement for plywood or particle board. It is dense, flat, stiff, has no knots and is easily machined. Its fine particles provide dimensional stability without a predominant "grain" (as is the case with lumber). Unlike most plywoods, MDF contains no voids, and will deliver sharp edges with no tearout.
Below are some metrics for MDF and other types of wood. Ex: Weight of MDF board. As you can see, MDF is very dense and heavy, but is not as stiff as other types of wood which is why bracing is suggested.
The modulus of elasticity (MOE), also called Young's modulus, is the ratio of stress to strain, where stress is the force per unit area placed on the item and strain is the deformation caused by the stress. The MOE is therefore a measure of stiffness.Q: What does MDF look like?
A: Here is an image of a birch veneered MDF board on top and for contrast an image of veneered particle board below. Notice the much larger and obvious particles.
A: While MDF has been in use for almost 30 years, it is only now becoming available to the general public. Finding MDF may end up being the single toughest part of using it. As its density implies, MDF is very heavy and thus potentially difficult to handle.Q: What are the safety issues to consider when working with MDF?
A: MDF is typically made with urea-formaldehyde resin totaling 9% by weight. While most people will not be affected by this, people sensitive to formaldehyde emissions should consider low formaldehyde or formaldehyde-free MDF, or consider methods of controlling these emissions through proper finishing. Finishes that work best at controlling formaldehyde emissions are solid add-on surfaces such as high pressure laminates, vinyl covering, and finished wood veneers. Less effective at controlling emissions are simple seal coats, oil and latex paints, danish oil, and wax. Plum Creek makes low-formaldehyde MDF, while Medite II and Medex from Medite Corp. are formaldehyde-free MDF.
Dust is another MDF hazard. The large amount of dust released when working MDF makes proper respiratory and eye protection mandatory. At a minimum use a dust mask. A respirator is preferable. Shop dust collection (or even a ShopVac) would greatly help the removal of dust from not only the air but also the working surfaces, making them easier to see. Goggles should always be worn while using tools.Q: Is all MDF the same?
A: No. MDF from different sources will vary in texture, density, color, etc.Q: How is MDF sold?
A: MDF is manufactured in sheets up to 8ft x 25ft. Typical consumer level sheets are 4x8 or 5x8 and 1/2 inch, 3/4 inch and 1 inch in thickness. Thicknesses can also be metric - an important consideration when considering the use of English system tools (such as router bits). MDF is also available with a variety of veneers and laminates pre-applied, which may affect its actual thickness.Q: What about MDO, particle board, hardboard, void-free plywood?
A: Medium Density Overlay and High Density Overlay are plywood products with a resin impregnated paper coating. They are often used for exterior painted surfaces. These are not fiber based products.
Likewise, particle board is not fiber based; it is a solid wood composite product. Along with flakeboard and other engineered lumbers, composite products are made from wood flakes, chips, splinters, etc., formed into layers and held together by resin glues and heated under pressure. Being layered and consisting of larger chunks, particle board does not have the uniform texture of MDF.
While MDF is a hardboard, the term hardboard is often used to refer to 1/8 or 1/4 inch thick HDF, usually containing a screen pattern on one surface. As previously mentioned, this is commonly referred to as Masonite.
Plywood is made from an odd number of lumber plies, each layer having a grain direction at right angles to the previous layer. This arrangement provides a dimensionally stable product. Void-free plywood uses plies with supposedly no holes, thus the completed plywood has in theory no voids. Baltic birch plywood is often sold as void-free plywood though some users have encountered small voids in these products. Be sure to ask specifically for void-free plywood if this is what you are looking for.Q: What should I use to cut and mill MDF?
A: MDF can be treated much like a fine grained hardwood. Its high glue content means that steel cutting tools will dull VERY quickly; thus the use of carbide tools is highly recommended. Always keep your tools sharp for efficiency and safety.
The following recommendations are from the The National Particleboard Association publication:
A: Availability varies geographically so there is no simple answer to this question. Hobbyists have found MDF from a wide variety of sources including, but not limited to :
As MDF becomes more popular you will see it more and more in your local hardware stores. Sometimes, they will only have smaller 2x4 pieces or 1x4 pieces designed for use as shelving, so be sure to look around or ask.
Beware of clueless store clerks trying to pass plywood, particle board or MDO as MDF ! Note that many lumber yards can special order MDF but may not realize this, so it never hurts to ask. Ask them to check their price book for availability.Q: What kind of joints can I use?
A: Because MDF can be milled to just about any profile, there are many possible joints. However, not all make sense in the context of speaker building.
MDF can also be edge glued to make larger surfaces, although this is not likely to happen except with exceptionally large speakers. Panels can be scarfed, doweled, tongue & grooved and finger jointed.Q: How may various fasteners be used with MDF?
A: Some typical fasteners and their uses follow :
Do not rely solely on the above fasteners for building speaker enclosures. This is especially true for butt joints. Combine glue with screws for a simple and strong joint.Q: What kinds of glues can I use with MDF?
A: Good glues to use are gap-filling glues such as polyvinyl acetate (PVA) typically known as yellow glue, modified PVA glues like Titebond II or white glues. Epoxy, urea and hot melt glues may also be used.Q: How can I finish my MDF ?
A: For that finished look, there are many options requiring different levels of woodworking skills.
Note that raw MDF is very porous. Use a generous amount of glue to ensure a proper bond.
Pre-Laminated MDF is a Medium Density Fibre Board, laminated on both surfaces by synthetic resin-impregnated base papers under the influence of heat pressure. Pre-laminated MDF boards are available in Interior and Exterior Grades, in both One side Laminated (OSL) and Both Side Laminated (BSL) varieties.
Pre-laminated MDF can be used for Modular Furniture, Computer Table, Office Furniture, Dressing Table, TV Trolley, Pre-laminated Doors etc.