Page 10 - CleanScience_Fall22

Figure 1. Three cutting methods for hardwood planks: plain, quarter and rift sawn. Source: 3-ply Engineered Hardwood Flooring, [email protected]
Figure 2. Veneer cutting methods, dry sawn face and sliced and rotary peeled. Source: SVB Wood Floors, 4200 Main Street, Grandview, MO 64030.
grain and absence of knots. These logs are cut into rough􏰀sa􏰁n 􏰂lanks􏰃 dried􏰃 and cut into 􏰂lanks using one of three 􏰄ethods 􏰅􏰆at or 􏰂lain sa􏰁n􏰃 􏰇uarter sawn and rift sawn) that affect the stability of the plank and cost (Figure 1). The cut planks are graded and planed on both sides and the tongue􏰀and􏰀groo􏰈e edges are cut to 􏰄ake the boards 􏰉t together. The tongue􏰀and􏰀groo􏰈e edge allows the board to e􏰊pand and contract without creating gaps between the planks.
􏰋 􏰌􏰍􏰎􏰏􏰍􏰐􏰐􏰑􏰐􏰒 􏰔􏰕􏰑􏰒􏰁􏰖􏰖􏰒 􏰆􏰖􏰖􏰑􏰏􏰍􏰎􏰗 This product is 􏰄anufactured using three to 􏰉􏰈e ply layers of wood in contrast to a single plank of solid hardwood. The crisscross layer structure provides dimensional stability so that each plank is less prone to moisture expansion and contraction. The top layer of wood is decorative and provides the 􏰆ooring its name (i.e., hickory, maple, walnut, oak, etc.). Both solid and engineered hardwood 􏰆oors are made entirely of wood, the difference is the construction method. The appearance of the top layer is achieved using one of two methods (Figure 2). A rotary cut veneer is produced by removing the top section of hardwood using a lathe that peels a thin layer of wood from the log to provide a view of the grain pattern. The slice veneer cuts a piece of wood by slicing perpendicular to the growth rings (quarter slicing), by slicing parallel to the center of the log (plain slicing), slicing
in an arc parallel to the center of the log (half round slicing) and straight cuts by slicing at a slight angle to minimi􏰘e irregularities (rift cut). The 􏰉nish looks like solid wood and can be sanded. The 􏰆ooring is intended to be installed by nailing or gluing on top of a sub􏰆oor such as a hardwood.
􏰋 􏰙􏰕􏰄􏰏􏰍􏰕􏰚􏰐 􏰆􏰖􏰖􏰑􏰏􏰍􏰎􏰗 This is a high􏰀density 􏰉berboard (HDF) laminate that feels soft. The upper wear layer is smooth. The 􏰆ooring looks 􏰛wood􏰀like􏰜 from a distance until examined closely. The wood appearance is a photographic layer that is coated with a clear 􏰉nish 􏰛wear􏰜 layer. 􏰙aminate 􏰆ooring is manufactured in a process that fuses four layers of wood together in a single press operation at high heat (>300°F) using direct pressure laminate (DPL) construction. The four layers are 1) an upper wear layer or clear topcoat, 2) a design or pattern layer of printed paper that is positioned on top of an inner􏰀 core, 3) an inner􏰀core substrate layer made of wood pulp that is adhered together in a 􏰆at panel, and 􏰝) a moisture􏰀resistant backing layer that is placed on the bottom to serve as a moisture barrier and to limit warping (Figure 3). In addition to the four layers, an underlayment padding is sometimes added.
There are two types of laminate construction􏰞 Direct􏰀 Pressure Laminate (DPL) and High􏰀Pressure Lami􏰀 nate (HPL). Direct􏰀Pressure Laminate 􏰆ooring is con􏰀 structed using 300 to 500 pounds per square inch (psi) pressure and is intended for residential or low􏰀traf􏰉c areas. High􏰀Pressure Laminate 􏰆ooring is constructed with an additional layer of paper sheets that are treated with a stronger resin that makes the top layer stiffer and more durable. These materials are pressed together using 1,300􏰀plus psi to maximi􏰘e their strength and are intended for commercial areas with high foot traf􏰉c.
􏰋 􏰟􏰕􏰄􏰠􏰖􏰖 􏰆􏰖􏰖􏰑􏰏􏰍􏰎􏰗 The most common species of bamboo for 􏰆ooring is 􏰡oso Bamboo 􏰅􏰢􏰔􏰣􏰤􏰤􏰖􏰥􏰚􏰑􏰕􏰦􏰔􏰣􏰥 edulis). Bamboo is in the grass family because it grows laterally using rhi􏰘omes. Bamboo 􏰆ooring may be constructed in a hori􏰘ontal or vertical orientation with a characteristic linear grain. During manufacturing, bamboo 􏰆ooring is divided into long strips that are boiled and dried to remove starch, insects, and sugars. The strips are glued together to form 􏰆ooring planks as thick as the width of the strips (Figure 4). Bamboo 􏰆ooring is known for its strength􏰧 however, the strand􏰀 woven bamboo comprised of shredded bamboo 􏰉ber is the strongest. In the strand woven manufacturing procedure, the bamboo is treated as above to produce a pulp that is placed in a mold and pressed under extreme
10 | The Cleaning Industry Research Institute
FALL 2022