Identify one key factor in determining the service life of treated wood.

The type and amount of preservative used is a crucial factor in determining the service life of treated wood because preservatives are specifically designed to protect the wood from decay, insects, and other forms of deterioration. Different types of preservatives have varying levels of effectiveness and longevity based on their chemical composition and the specific threats they are designed to address. For example, copper-based preservatives can be very effective against fungal decay and insect damage, while alternative preservatives may target specific environmental conditions.

The concentration of the preservative is also significant; higher retention levels often correlate with extended protection and, therefore, a longer service life. This means that both the choice of preservative and the prescribed treatment level can directly influence how well the wood performs over time in various environmental conditions.

While factors like geographical location and exposure levels impact wood decay dynamics, they are secondary to the inherent protective characteristics provided by the type and amount of preservatives used. The color of the wood, while it may relate to aesthetic preferences, has no bearing on the wood's durability or resistance to deterioration.