Spalted Maple is not a species of maple. Spalting is a term that refers to the process of decay performed by fungi who earn their living by breaking down and consuming dead wood – but what a process it is! If captured at the right moment, before the wood is too broken down, spalting produces wood of exceptional beauty. The fungi will create areas of pink, white, purple and brown delineated by fine black lines that appear to be drawn by hand. Spalted Maple is rare and each piece is visually distinct and unique.
Spalting occurs in other species such as Beech, Birch, Poplar and some imported species like tamarind. Maple is the most popular and preferred species since its wide, white sapwood provides a blank canvas for the fungi to demonstrate their magic. Maples initial hardness makes it easier to find wood that is sound, as it is harder for the fungi to break it down. All maple species will spalt, but Sugar Maple seems preferred by woodworkers.
Spalting is a natural process that requires wet wood. Green wood with a moisture content above 40% is perfect for fungal growth. Once the moisture content drops below 20% the fungi stop growing. Kiln drying will essentially kill off the fungi and stop the decay process. Warm temperatures are also preferred by the fungi for optional growth and the process will slow when temperatures fall below 50 degrees F.
Various species of fungi are responsible for the spalting process. White rot fungi are responsible for areas that are coloured white and the production of soft, punky wood as they consume the lignin and cellulose present in the wood. Other species of fungi are involved in the production of the other remarkable colours present in Spalted Maple. These colours are produced by pigments metabolized by the fungi and deposited in the wood. All of these fungi will interact with each other, with some species providing the environment and conditions for other fungi to grow. The black lines are produced when adjacent areas of fungal growth create barriers between each other; they are protecting their own turf, so to speak.
Most Spalted Maple is found material. Fallen logs, stumps and neglected air-dried lumber are common sources. The decay process starts quickly as the fungal spores are always present in the environment. The time to produce spalted material is variable since each fungi has its own timetable for growth. It can take several years for the process to produce visually interesting pieces. Too little time will not allow the fungi to work their magic. Too much time and the wood will deteriorate and be unsuitable for use. If an interesting spalted piece of lumber is found, it must be dried quickly to stop the fungi from further growth.
Working with Spalted Maple can be a challenge. Tooling must be very sharp. The best surface is produced with a sharp hand plane. Punky and soft areas will tear. If you have to sand, the paper must be backed by a rigid backing surface or the soft areas will be scooped out. Soft areas can be hardened with crazy glue or epoxy. Larger areas of punky wood can be consolidated with commercially available hardening agents. Turners must also keep their tools sharp and be aware of tools catching on the softer material as it is turned.
Water-based acrylics are a good choice for a finish product. They are available in matte or gloss finishes and dry clear allowing the beauty of the wood to show. Blond shellac is also a good choice for a sanding sealer or a final finish. Oil based finishes tend to be absorbed unevenly creating a blotchy finish that can obscure the wood. All finishes should definitely be tested on some scrap material to expose any potential finishing problems in this unpredictable wood.
Spalted Maple excels as a visual design element in woodworking projects. It is used in panels, drawer fronts, turned objects, decorative boxes or any project where its sublime beauty will enhance the visual appeal of the piece. It is also used in musical instruments, particularly solid body guitar tops. It should be avoided for structural elements where areas of decay can make joinery difficult at best.
Health concerns are often raised about Spalted Maple. None of the fungi involved in the spalting process are considered to be pathogenic. However, some molds can be present during the decay of the wood that cold be problematic. Always work in well ventilated conditions. Working with green wood, sanding or any procedure that produce fine particles require a dust mask as a minimum level of protection. Once dry, Spalted Maple is safe to use.
Spalted Maple is usually found and sold by specialty lumber dealers. It is usually available as short pieces of lumber and/or turning blanks. Spalted Maple is expensive and is dependant on the amount of spalt present and how sound the wood is. Expect a lot of waste as you work around the areas of decayed wood. Given how rare it is, some woodworkers have attempted to make their own Spalted Maple. Results are uneven and tend not to compete with what nature can produce. If you want to try your hand at making your own spalted wood, there are resources available on the web.
Spalted Maple is so rare and can be so beautiful, it is hard not to buy some if you are fortunate to come across it. Even if you do not have an immediate use for it, it will provide inspiration for future projects. If you invest your time and skill in working Spalted Maple wood, you certainly won’t regret spending your money on it.