Revealing Fibril Angle in Wood Sections By Ultrasonic Treatment

An effective method for inducing cell-wall checks in a microtomed wood radial section by ultrasonic treatment is described. Congo Red enhances cell-wall fibrillation in ultrasonic-treated sections. The amount of fibrillation and checking increases as ultrasonic treatment continues. However, too much fibrillation generated either by prolonged ultrasonic treatment or by Congo Red enhancement may visually obscure the checks. Less than three hours of ultrasonic treatment at 47 kHz frequency was found to be satisfactory to induce checks in 15-μm-thick southern pine sections. The ultrasound check-inducing technique is most effective on southern pine fibers with large diameters and high fibril angles