Did you know? - Assessing Propensity for Intra-ring Checking

Intra-ring Checking

Did you know you can assess stands for the propensity for intra-ring checking (IRC)? IRC is an intermittent wood quality issue but is critical in some appearance product lines.

IRC is the checking that occurs within earlywood bands of radiata pine sapwood, primarily in the butt log. It is different to drying checks caused by stress and end-drying that typically cross growth rings. It can be described in simple terms as cell columns splitting apart from each other under increased water tension during drying.

Sampling technique - core based method

The collapse of 12mm increment cores, after over-drying, is assessed. See photo below - the core displays severe collapse in the sapwood on oven drying. This equates to high IRC in lumber.

The core based method is now being routinely used by some forestry companies, such as PF Olsen, for assessing stands where intra-ring checking might be an issue. The method is based upon sampling around 20-30 trees per stand.

Implications for Tree Breeding

The Radiata Pine Breeding Company assess breeding material and cull stock which have a high propensity to develop IRC. This provides a long-term solution to the issue but doesn't help people with trees in the ground.

What are the Benefits of Assessment of Intra-ring Checking?

As with most research from SWI, the primary objective of techniques to identify and segregate inherent wood qualities is to eliminate wasteful cost. Generally, the closer this segregation can occur to the forest resource, the greater amount of wasteful cost can be eliminated. Wasteful cost occurs in many forms and includes transporting, handling and processing logs which, at some point along the supply chain, prove to be unfit for purpose. The greatest wasteful cost occurs when a wood product is installed in an end-use application and then fails, requiring a full refit to remedy the problem.