Some experiments on very resinous Longleaf Pine specimens indicate an increase in <answer>strength</answer>, due to the resin which increases the <answer>strength</answer> when dry. Such resin-saturated heartwood is called "fat lighter". Structures built of fat lighter are almost impervious to rot and termites; however they are very flammable. Stumps of old longleaf pines are often dug, split into small pieces and sold as kindling for fires. Stumps thus dug may actually remain a century or more since being cut. Spruce impregnated with crude resin and dried is also greatly increased in <answer>strength</answer> thereby.
If spruce is shot full of crude resin and dried, which of its properties is increased?
strength