Burr (or burl) walnut veneer Burr (or burl) walnut veneer is a wood veneer that was used to decorate ‘top-of-the-range’ clock cases during the 1600s and 1700s. Known for its rich dark colour, it was (and still is) considered one of the most attractive varieties of walnut because of its uniquely beautiful and intricate grain patterns, including swirls, knots and irregular growths. Burr walnut veneer is sourced from the burr wood of the walnut tree. The is the wood near the base of the trunk, where growths sprouting smaller branches occur, or at the tree's root system. Sourcing the wood from this part ensures the likelihood that the veneer will display intricate patterns. The English walnut tree (Juglans regia) is a deciduous broadleaf tree that can grow to a height of 35 meters. Its trunk is smooth and soft with few ridges. By way of contrast, the bark of black and dark walnut trees (Juglans nigra) is harder and grooved. It is the darker walnut wood that is coveted for veneering. Black and dark walnut trees are native to North America and found throughout the United States. The darker variety also grows to maturity much faster than its British counterpart. The harvesting process involves carefully cutting the wood from the burr and preserving as much as possible in one single cutting. The cutting is then cut into thick sheets or slices using a rotary cutter. These slices are very thin, often less than 1.6 mm. The next stage of the process is to boil the burr slices at a specific temperature over a period of days. The slices are then dried to reduce moisture content – a crucial process that prevents warping, cracking and other malformations. Next, the veneer is 'backed' with another material, such as paper, fabric or wood, to enhance its stability and durability. Finally, the veneer is sanded until its surface is smooth. Sometimes it is further treated with stains, dyes or coatings to enhance its appearance and protect its shiny surface. Burr walnut veneer was used by makers such as Thomas Tompion, Christopher Gould and Daniel Delander. It was also used for fine furniture and decorative objects during this period. For examples of clocks with burr walnut-veneered cases see Tompion's Millbourn Tompion Longcase No. 333 made around 1699 and Gould's Musical Moonphase Longcase made around 1701. Burr walnut veneer is still very popular. Seen as timeless and classic, it is used for luxury items, such as car dashboards, aircraft interiors, musical instruments, marquetry, decorative wall panelling, furniture, cabinets and other wood objects, as well as carvings and inlays.