With the development of technology, more and more building and finishing materials appear on the market. At the end of the last century, we got MDF. There are MDF boards that are used in construction work, there are finishing panels that can be used to decorate walls / ceilings or make furniture.
What is MDF and how is it made?
MDF appeared on our market in the last years of the last century, and it was invented in the USA in the late 60s of the 20th century. You can understand what MDF is if you translate its English name – MDF – Medium Density Fiberboard. In Russian, this translates as “medium density fiberboard.” That is, a Russian-language name was formed with the help of transliteration – instead of Latin letters, they put similar Russian ones. Common, for our language, phenomenon.
Manufacturing process
MDF is made from wood, ground to a state of very small chips, almost to the state of fibers. Mostly wood waste is used, so the release of this material does not harm forests.
The ground wood is cleaned of sand and other foreign inclusions, washed, dried. The prepared mass is heated, a tape of the required width is formed from it, and then pressed. Under pressure, a natural binder, lignin, is released from heated wood fibers. It is he who is the binder in this material. The final shape of the products is given in the finishing press, which squeezes out the remaining air from the mass, forming a homogeneous MDF structure.
After pressing, the cooled material is fed to grinding, where flaws on the surface are removed from the MDF, and the material is brought to the required thickness.
Not all types of wood provide a sufficient amount of binder. Then add a similar, previously isolated, lignin or other natural binder. Of all sheet wood materials, MDF is considered the safest, since the binder is natural, and the formaldehyde emission is comparable to wood (emission class F1, that is, it is allowed to use furniture for children’s and medical institutions).
Fibreboards can be given special properties during production. Basically, moisture resistance additives increase moisture resistance and reduce flammability.
Appearance and release forms
In a “pure” form, the material has a grayish-brown color, a homogeneous dense mass on the saw cut. The exact shade depends on the type of ground wood and the amount of bark. In this form, the material is used as a building sheet – for the construction of light partitions, leveling walls.
The surface of MDF can be “ennobled”. It can be painted, laminated with PVC film, pasted over with veneer or plastic. This gives a fairly large number of design options, which is used in the furniture industry, in the production of finishing materials.
The production technology allows to form products of various shapes, thicknesses, sizes. During finishing pressing, it is possible to form a certain relief, which is used in the manufacture of furniture and doors. Finishing materials are also made from MDF – plates, panels. They make skirting boards, platbands, and other moldings from it. All these materials can be used for interior decoration.
The structure of MDF is fine-fibered, dust is formed during milling, which makes it possible to produce carved products. This is used in the manufacture of carved decorative elements – panels, screens for heating radiators, decorative grilles, figured furniture facades.
MDF or chipboard – which is better?
Having appeared on the market, MDF created competition for fiberboard. This was facilitated by its properties:
- with an equal thickness, MDF is twice as strong as chipboard;
- the mass is very plastic and allows you to form reliefs of any complexity;
- easier to process;
Even in appearance it is clear which is better – chipboard or MDF - uniform smooth surface allows even painting and laminating PVC to get a good appearance suitable for the furniture industry;
- has a lower formaldehyde emission factor;
- does not change shape with temperature changes.
All this led to the growing popularity of the material. Even despite the fact that MDF is more expensive than chipboard. To some extent, MDF even competed with wood. For example, skirting boards, MDF trims, and finishing panels are increasingly being used. This is due, firstly, to lower cost, and secondly, to greater practicality. Wood requires regular maintenance – painting, varnishing. MDF does not require special care. It is simply wiped with a damp cloth, if necessary using a liquid detergent.
MDF boards
MDF board manufacturing technology allows you to vary the density over a wide range: the minimum figure is 760-780 kg / m3, maximum – 1100 kg/m3 and even higher. A material with a lower density is used where the abrasion load is low: in the furniture industry, for wall and ceiling decoration.
High-density MDF boards are used for flooring. The material of this category has a high resistance to abrasion: one and a half times higher than that of oak (oak – 6,9, MDF – 10-11). If we add that the coefficient of distortion along the diagonal is only 1,2 mm per meter of diagonal (for plywood 15 mm), the love of furniture makers and finishers for this material becomes clear.
Dimensions and tolerances
One of the most popular forms of release is slabs of different thicknesses and formats. They can be found with the following options:
- thickness – from 3 mm to 40 mm;
- width 2800 mm;
- length – 1250 mm, 2170 mm.
The length and width of the MDF board is standard, but the thickness may be different
It is convenient to work with MDF boards, since this material has very small tolerances for dimensional deviations:
- the difference in thickness cannot exceed 0,2 mm (for plywood 0,5-2,5 mm);
- length may differ by no more than 5 mm;
- the run-up in width cannot be more than 2 mm.
When joining two sheets, the difference in thickness or size is very small or not at all. Therefore, the finishing of MDF with sheets or panels is moving forward quickly.
Types of surface finishes for sheet material
MDF boards are available with different types of surface treatment:
- Sanded. Grinding can be on one or both sides. Such material is good for painting, applying putty. If you use it to level the walls, it is advisable to putty it under light wallpaper, and then prime it. Dense wallpaper can be glued on top of the primer without puttying.
- Laminated (coated with PVC film). Usually lamination is done on one side, but you can find it with a double-sided coating. Usually the film repeats the color and texture of different types of wood, but it can also be smooth – matte or glossy. This type of material is used for the production of furniture, finishing wall panels. From the laminated subspecies (also called LMDF) they make cabinet furniture for living rooms, kitchens and even bathrooms. Moreover, for the facades of kitchens they use the usual one, for countertops and furniture in the bathroom – moisture resistant with hydrophobic additives, which give increased resistance to water and steam.
MDF can be covered with a layer of veneer or PVC film with a repetition of the wood structure - Veneered. MDF boards are pasted over with the thinnest cuts of precious wood – veneer. The appearance is very similar to solid wood. The disadvantage of this type of material is the high price. Of course, it is lower than similar solid wood products, but not as low as veneered chipboard.
- Lined with plastic. Another type of finish, which is used mainly in the furniture industry.
If we talk about construction and repair, then they use polished MDF boards in them. When leveling walls or installing light partitions, when leveling floors and ceilings. Here is an example of their scope.
Frame mounting
If the surface of the walls or ceiling is uneven (deviations are more than 1 cm), the method of mounting sheet MDF is the same as that of drywall – on the frame. The frame is usually assembled from wooden bars, but no one forbids putting profiles under drywall. The cross section of the bars is selected based on the irregularities of the wall – they must compensate for all the difference in height. Most likely, you will need bars of 20 * 30 mm or something like that. They are stuffed horizontally in increments of 40 cm. With this step, the joints of the sheets (they exist if the ceiling height is higher than 280 cm) fall on the bar.
Under the installation of sheet panels from the same beam, vertical jumpers are installed. They are placed in increments:
- 54. 3 cm – for sheets 2170 mm wide;
- 42,3 cm or 63,5 cm for a width of 1270 mm.
The step of installing vertical jumpers depends on the thickness of the selected material. For thin sheets (3-4 mm) it should be smaller, for thick sheets (5-6 mm) you can do more.
MDF sheets / plates are attached to the assembled frame. The peculiarity (compared to drywall) is that for hidden fastening it is necessary to drill holes under the fasteners. Otherwise, fasteners will not go into a dense plate. To prevent the caps from sticking out above the surface, the hole is expanded under them using a larger diameter drill.
After installing the screws, holes remain on the surface. They are sealed with putty. If further puttying of the walls is supposed, they act as when installing drywall – first they close up the holes with putty, immediately removing the excess with a spatula. After drying, putty places are passed with fine-grained sandpaper – in order to finally get rid of possible irregularities. Then, after dusting the surface, they begin to putty the walls.
Installation on glue
If the walls are even, you can mount MDF boards without a frame – on glue. You can use liquid nails or a composition like CM-11. The order of work is this:
- The composition is applied to the surface of the sheet in a zigzag or island pattern.
- They put the sheet against the wall, press it, align it in a plane. Align by tapping on the protruding parts with a fist, while checking the position with a level (it is necessary to control the vertical and horizontal).
- Hold in the desired position for several minutes.
- Install the next sheet.
- After the glue dries, seal the joints with putty.
It is difficult to mount large sheets on glue
So that during the installation process the sheet does not move anywhere, you can make holes in the corners and, after leveling, fix the sheet. Even if the self-tapping screw will only stick in the plaster, this will help, as it is only required at the initial stage – until the glue begins to harden.
This method seems simpler and less expensive (due to the lack of a frame), but leveling bulky MDF boards is not at all easy. It is better to try on a small section of the wall. The point is that it is impossible to disassemble the installed. Only if the skin is completely destroyed. So it is worth considering which method is better.
Installation of sheet MDF on the floor
For laying on the floor, moisture-resistant MDF boards of high density are chosen (from 900 kg / m3 and higher). Sheet thickness – from 5 mm when laying on a subfloor and from 10 mm when mounted on logs. In this case, the installation method is similar to leveling the floor with plywood, only the gaps are smaller, since the wood board changes its parameters much less than plywood. The rest of the rules are the same:
- First, the base is leveled to the horizon and cleaned.
- Plates are laid with a gap of 2-4 mm from the walls.
- When laying, they monitor the mismatch of the seams (stacking).
- The expansion joint between the plates is 2-3 mm.
The melts of laying sheet material on the floor do not change – apart - Fasteners are installed around the perimeter in increments of 10-15 cm, in the plane – in increments of 20-25 cm (or along the log).
- Holes are drilled under the fasteners, with an extension for the cap.
- Holes after installing fasteners and joints are sealed with putty.
After sanding the putty, the MDF floor surface is ready for painting. If you do everything carefully, you get a perfectly flat floor. This base can also be used as a base for flexible finishing materials or under a laminate.
Finishing panels MDF
Finely dispersed pressed boards serve as the basis for the production of decorative finishing panels. The front surface is covered with paper. This is the cheapest option. Slightly more expensive ones are laminated with PVC film. There are also panels covered with veneer. This is a more expensive material. There are also options with plastic, but very rarely.
Decorative MDF panels are most often sheathed on walls, sometimes on the ceiling. This method of finishing saves time: the surface is both leveled and immediately takes on its final form, since additional finishing is not required.
Types of decorative MDF panels
It will not be about colors and shades, but about the shape of the intake and the type of decorative surface. The shape of the finishing panels made of pressed wood fibers are:
- Rack type. The length is many times greater than the width. Length 2,0 m – 3,0 m, width from 150 mm to 250 mm. When choosing, pay attention to the thickness of the panel (from 3 mm to 9 mm) and the depth of the lock. Ideally, the lock (protrusion) should be at least 5 mm. In this case, the docking of the slats will be easy and hassle-free. Mounted on the frame, fastened to the tongue or groove using self-tapping screws.
Linear type MDF panels - Tiled type. Rectangular or square slabs. The maximum dimensions are meter by meter, but rectangles with different aspect ratios are more common. Mounted on the frame or directly to the walls using a special system of hidden fasteners, fragments of which “cling” to the ledges of the plates.
Tiled type – in the form of rectangles of different sizes - Sheet panels. They are rarely used for interior decoration, more often for cutting in the manufacture of furniture. But, if necessary or desired, they can also be used as a finish, often installing clamps.
When choosing MDF panels, pay attention to the type of finish. The cheapest material is covered with paper, on top of which a thin layer of protective coating is applied. It is clear that such a surface is quickly scratched, it can only be wiped with a soft, slightly damp cloth. You can not even use a rough sponge, otherwise light spots form. Such MDF panels are good for finishing the ceiling – there is no mechanical load at all. If you install them on the walls, it is better to immediately cover with two layers of varnish. You choose the type of surface yourself – gloss, semi-gloss, matte, semi-matte … It is important that the film is durable.
More expensive ones – with PVC and veneer – do not require additional finishing, but at a price of 2-3 times more expensive. If the budget is limited, the option described above is not bad.
Mounting methods
MDF panels are mounted either on a frame or directly on a wall using glue. The technology is described in the previous paragraph and differs only in that clamps are used for installation – special mounting plates for flush mounting. The first panel on the wall is installed in the corner. Here it is fastened through with self-tapping screws. All the rest are fixed with clasps. After the installation is completed, the corners are closed with a special corner profile. It is mounted on glue – applied in a thin layer and pressed at the installation site.
There is also a system of profiles – starting, finishing, connecting and corner (outer and inner corner). But this fastening system is more expensive, it is used with MDF panels finished with veneer, square or rectangular format.
There is another subtlety of mounting decorative MDF panels on the ceiling. If you use thin sheets / strips – 3-4 mm thick – you need to install suspensions often, otherwise the material will bend under its own weight. When using plates 6-8 mm thick, suspensions can be installed less frequently. They are more rigid and do not bend. But the weight of the finish will be greater, so you will have to use more powerful guides and suspensions themselves.