I'd like to know about the materials and specifications of preserved wood.

1. Western Red Cedar.
Western Red Cedar is the highest grade decay-resistant lumber in North America. It is also suitable for high-humidity environments such as saunas, bathrooms, and kitchens, and is used to make cabinets, wardrobes, etc., which are resistant to cockroaches and insects. Red cedar has excellent stability, a long lifespan, and is not easily deformed. Its excellent decay resistance comes from a naturally occurring alcohol called Thujaplicins; in addition, a substance called Thujic acid, which can be extracted from red cedar, ensures that the wood is not eroded by insects, eliminating the need for artificial preservatives and pressure treatment. Western Red Cedar is popular in the global market due to its chemical-free and purely natural characteristics.
2. Yellow Pine (Southern Pine).
Yellow Pine (Southern Pine) has the best strength and specific gravity, excellent nail-holding power, and is the strongest western softwood. The product can be used in seawater or river water without any corrosion. In pressure-treated yellow pine, the preservative penetrates deep into the wood core. It can be cut arbitrarily during installation, and the cut surface does not need to be re-brushed with preservative.
3. Spruce-Pine-Fir (SPF).
SPF grows slowly, resulting in wood with a fine texture, small knots, and excellent resistance to denting and bending after drying. Its strength is similar to hemlock and higher than most softwood species; it is also easy to paint and stain. The product has higher stability and a fine surface finish.
4. Hemlock.
Hemlock is currently one of the most elegant and versatile species on the North American market. Pressure-treated hemlock lumber is both beautiful and strong, comparable to the naturally durable North American red cedar. In terms of strength, it is slightly lower than yellow pine, making it suitable for preservative treatment. Hemlock maintains stable shape and size, without shrinkage, expansion, warping, or twisting, and is resistant to sun-darkening. While almost all wood darkens after prolonged sun exposure, hemlock retains its freshly sawn color even after years of sun exposure. Hemlock has strong nail-holding power and excellent bonding properties, accepts various surface coatings, and is very wear-resistant, making it an economical wood suitable for various outdoor uses.