Understanding Wood Treatment Options for Longevity
Wood has long been used as an essential building material, with centuries of history attesting to this fact. Though naturally vulnerable to decay, pests, and environmental wear-and-tear, modern treatment techniques have drastically extended its longevity and durability.
These treatments offer numerous advantages for contractors’ projects, including protection from insects and fungi infestation, improved dimensional stability, resistance to weather fluctuations and temperature swings, as well as greater resistance against weather changes and temperature variations. By understanding all available treatment methods contractors can select one best suited to their projects.
Pressure Treatment
When building decks, fences, sheds, gazebos or garden boxes outdoors it’s common practice to use pressure treated wood, which has been treated with preservatives and fire retardants to extend its life and provide extra durability. This process is known as pressure treatment. It provides an economical option that may save on wood costs in the long run.
Preservative chemicals are forced deep into wood’s cell structure via this process, creating an impregnable defense against biological deterioration such as insects or fungus that might otherwise attack its health, according to McCown. He states this approach can be particularly useful for wood which will come into direct contact with soil, water, or harsh environments.
Most commercial PT lumber is treated with arsenic- and copper-based preservatives such as chromated copper arsenate (CCA), ammonium copper zink arsenate (ACA), or micronized copper azole (CA), to protect it against decay, pests, termites and other wood-eating insects. Marine-grade lumber typically features stronger preservatives specifically tailored for saltwater exposure.
To activate chemicals, wood must first be immersed in preservative under pressure for an extended period of time, depending on its species and level of protection required. Once immersed, any defects such as knots must be sanded down before debarking with equipment such as rosserheads or ring debarkers; incising may also be used with some western species to enhance penetration during this soaking process.
Preservative formulation has evolved over the years, but their approach remains unchanged. The AWPA works closely with chemical manufacturers and testing labs to develop new options, but their basic process hasn’t. When testing potential new preservatives, scientists bury three samples of wood about one meter apart at locations that replicate what the lumber might be used for, and compare results over time to ensure the formulation will stand up against insects and fungus that often damage wood products.
Wipe-On Oil Finishes
Oil finishes are easy to apply and provide wood protection against water, household chemicals, food stains and wear. Oil also gives curly or figured wood the appearance of natural graining with no dust-sensitivity or handprints showing through when applied correctly; filling all open pores of wood pores to provide a barrier against rot, mildew and insects.
Wipe-on oil finishes come in various varieties, such as oils, waxes and urethanes. There are even combination products that combine these elements. It’s important to understand how these finish products are labeled and their variations.
Remind yourself that most wipe-on finishes can raise the grain of almost any wood species, due to cut fibers resurfacing when the coating dries – similar to when your hair grows back after being washed. Grain raise is easily remedied by lightly sanding using 220 grit sandpaper or #0000 steel wool pads.
There are other important considerations when applying oil finishes to your project. The type of oil chosen will have an impactful influence on its results and duration; raw linseed oil produces an organic look but only provides moderate water resistance once it cures for several days; by contrast, boiling linseed oil cures in about 24 hours but remains soft without offering much added protection.
Tung or Danish oil provides excellent water resistance and is commonly used to create traditional clear finishes, while being available in various colors, food-safe options and even easy application using just a lint-free cloth.
Advanced Techniques
Wood treatment is an essential step in ensuring wooden structures will stand the test of time. Although initial costs may be higher than untreated materials, due to increased longevity and decreased maintenance requirements it proves more cost-effective in the long run.
Wood treatments not only increase its durability, but can also enhance its aesthetics and workability for professionals and DIY enthusiasts. While ancient civilizations used crude methods such as applying oil or tar to wooden structures to protect them from rot and insect damage, modern wood preservatives offer greater precision and effectiveness in protecting wood structures against decay.
Modern wood treatment processes include thermal modification, which involves heating wood to high temperatures without oxygen in order to alter its chemical composition and significantly alter moisture resistance. This process also decreases decay sensitivity while improving workability (Mustafa and Xing 2024). Acetylation, another wood-retreat process, converts free hydroxyl groups in wood into acetal groups that make it less vulnerable to moisture and fungus while simultaneously improving workability (Mustafa and Xing 2024).
Understanding the differences among various wood treatment and oil products available to contractors will enable them to make informed decisions for their construction projects. Once they’ve chosen their ideal treatment or oil product, contractors need to maintain its integrity through periodic reapplication and regular cleaning to extend its lifespan and ensure it remains safe and visually appealing for years afterward. By adhering to manufacturer guidelines contractors can help ensure their treated wood will stay safe and appealing throughout its lifespan.
Tung Oil
Tung oil is a natural finish that provides exceptional water resistance. It can be used to protect butcher block tops, wood countertops and wooden bowls from mold and mildew. Tung oil is food-safe and has a pleasant odor. It also dries to a very hard and shiny surface. To keep tung oil looking fresh, it must be reapplied periodically, depending on the type of use and location. Re-oiling is easy, as it only requires that the surface be damp and then wiped with a cloth.
Before applying any finish, it is essential that the work surface be thoroughly cleaned to remove any dust or debris. Once the work area is clean, sand the surface progressively from coarse to fine grit to ensure that the surface is smooth and ready for finishing. Sanding can be done using a hand or power sander.
The wood is then ready to be treated with either pure tung oil or a wiping varnish. If using a pure tung oil, it should be applied liberally with a brush, pad, roller or sprayer. Once it has been allowed to absorb into the wood for 45 minutes, excess tung oil may be removed by wiping the surface with clean rags.
It is important that the correct product is used because not all tung oils are created equal. Some may be diluted with petroleum distillates, which can compromise the integrity of the finish. It is recommended that you only use products that are labeled as ‘pure’ or ‘100% tung oil’.
It is also important to note that the application process for tung oil can be quite messy. It is highly advisable to apply the oil in a well-ventilated area and wear gloves for safety.