General characteristics: The sapwood and heartwood have white to white-grey color. It is characterized by moderate resistance to weather conditions, but it is not resistant to fungi and insects infestation.
Physical Properties: It is of soft to medium hardness, moderately lightweight elastic and solid. It has good stability, it shrinks a little, is good at drying and easy to process. The cross section gives generally oval knots. When processing, it releases a very unpleasant smell.
True density at 15% humidity: 0.50 g/cm3
The contraction rate % in 1% change in moisture content in the direction of the heartwood is from 0.10 to 0.15 % while in the direction of the annual growth rings is from 0.28 to 0.33%.
The quality graduations in Fir trees are the following.
Clean timber, without transformations and compression wood. Allowed: In each meter 1 knot or 1 resin pocket, small shakes and wanes, deviation from flatness (bending) up to 2 cm/m2.
Without compression wood. Allowed: In every square meter 1 knot, slight discoloration in places, small resin pockets, small shakes (and in the edges), small wanes and deviation from flatness (bending) up to 2 cm/m2.
Without insect holes. Allowed: In every square meter 2 small dead knots, discoloration in places, small resin pockets, small shakes (and in the edges) and small wanes.