It’s time for Cabinetry 103, our final lesson in cabinetry. In Cabinetry 101 we covered the differences between stock, custom, and semi-custom cabinetry. In Cabinetry 102 we discussed framed and full access cabinets, and the door types of each. In this session, we’ll explain the styles of cabinet doors you can select, as well as decorative inserts.
These types of cabinet doors are almost like picture frames. Separate pieces of wood, engineered wood, medium density fiberboard (MDF), or solid hardwood surround a panel in the middle. The vertical sections of the frame are called stiles and the horizontal sections are rails. The stiles and rails are joined together using one of three methods:
Though the panel is called solid, it is not usually made of a single piece of wood. Wood expands and contracts with changes in humidity, and this can cause the door to split and crack. To counteract the problems of natural movement in a solid wood center panel, the panel is usually constructed using several pieces of solid stock lumber glued together. The wood strips used to construct the panel may not all match in graining and color. The panel is then cut on all four sides, so the center is higher than the edges. The face of the panel is usually flush with the front surface of the stiles and rails, with the edges forming a tongue which fits a corresponding groove cut into the door frame. The groove is slightly larger than the panel’s edge to allow the panel to float in the frame. This simply means that the panel has room to expand and contract during humidity changes, reducing the risk of the panel cracking or splitting.
Veneer is simply a thin slice of wood taken from a log, rather than a heavy board. Instead of solid wood strips, the core (substrate) of the veneered panel is particleboard , or in some cases plywood, which gives the cabinet door much more stability than wood. The veneer slices (leaves) are edge-glued into a face. This face is made to fit the size of the panel. The method of matching the veneer edges determines the final appearance of the door panel. A veneered center panel has a continuous graining, which some people prefer to the variety of the solid wood panel. While the final assembly into the frame is the same as for solid panel doors, veneered panel cabinet doors are less expensive than solid wood.
These cabinet doors are made of a single slab of MDF (medium density fiberboard) that is molded to give the appearance of a center panel and frame. Flexible vinyl is laminated to the substrate using industrial adhesives, heat, and pressure. The stability of MDF makes this cabinet door type resistant to cupping and warping.
A mullion is a thin strip of wood that is used to separate the panes of glass in a door or window. Mullion cabinet doors have glass inserts in place of the typical solid center panel and look similar to windowpanes. The glass can be individual pieces sandwiched between two mullions, front and back, or a full sheet of glass mounted behind the mullions. Usually the latter type of installation of the glass allows for it to be removed for easy and complete cleaning – although it increases the risk of breaking the glass. Since the mullions create a pattern of their own, the glass choices for mullioned doors are usually limited to clear Annealed (not a safety glass), or Tempered, or Laminated glass.
Frames only (cabinet doors without panels) are generally available in all styles. Most doors (12″ or wider and up to 42″ high) can be routed out on the back of the frame to hold the glass panel. Generally molding is not furnished for the back of the frame.
Glass that has been cooled with precise control to relieve stress introduced by the manufacturing process. This annealing process makes the glass workable, i.e. easier to cut, machine, etc. Common household glass is annealed glass. It is NOT a safety glass.
Tempering uses either a thermal or chemical process to quickly harden the glass, which compresses its surface. Compressing the surface increases the amount of tensile stress that can be endured before breakage occurs. It is important to note that the treatment must be applied only after all cutting and processing has been completed, as once ’toughened’, any attempt to cut the glass will cause it to shatter. The process of making tempered glass increases the surface tension of the glass which can cause it to ’explode’ if broken; this is more a dramatic effect than hazardous. When it does break, tempered glass generally breaks in very small pieces. Fully-tempered glass may show more visual distortion of reflected images, but it is about four times stronger than annealed glass of the same thickness.
Laminated safety glass is made by bonding two or more layers of glass with one or more layers of other material (such as resin, or PVB or other suitable materials). The most important characteristic is the ability of the interlayer(s) to support and hold the glass when broken. Laminated glass is 50 percent to 90 percent as strong as annealed glass of the same thickness depending on exposed temperatures, aspect ratio, plate size, stiffness and load duration. However, the edges of laminated glass are less resistant than annealed glass to handling and installation damage. When broken, laminated safety glass is held together by the adhesives that are used in the manufacturing process. This generally helps keep large pieces of glass from falling from the opening. Nevertheless, small pieces and or chips may still fall, and the precise size of pieces of glass that will break is difficult to identify and describe. Laminated glass, however, can be made with both heat-strengthened and fully-tempered glass for additional safety benefits.
Sand is sprayed at high velocities over the surface of the glass, giving the glass a rough, translucent surface. During sandblasting, only the areas that are to remain transparent are masked for protection. The depth and degree of the translucency of the sand-blasted finishing vary with the force and type of sand used.
Patterned glass has a textured surface with a patterns impressed on it. Patterned glass is made with a rolled glass process. The semi-molten glass is squeezed between two metal rollers. The bottom roller is engraved with the negative of the image. The resulting glass usually transmits only slightly less light than clear glass. This concludes our cabinetry series.