Wood-borne formaldehyde varying with species, wood grade, and cambial age

While the formaldehyde issue primarily focuses on adhesive systems used in wood-based panels, natural wood itself contains detectable formaldehyde. Potentially, this wood-borne formaldehyde is emitted over time; therefore, even with wood alone no "zero emission" is evident. In this work, the variation of formaldehyde contents in important commercial wood species that are dried and converted to wood particles for wood-based panel production was studied. Furthermore, whether wood grade or juvenile vs. mature wood have any effect on the formaldehyde content was determined. Results indicate that formaldehyde varied up to 4-fold across commercial softwood and hardwood species, but remained at low concentrations (under 1 mg/100 g). Softwoods generally had higher formaldehyde contents than hardwoods, while wood grade seemed to have no effect. The differences between juvenile and mature wood, however, were much more expressed. The lowest formaldehyde content was seen with juvenile wood from beech (under 0.15 mg/100 g), and the highest concentration was found in mature pine wood (approximately 0.70 mg/100 g).