Melamine-urea-formaldehyde resin (MUF), phenol-resorcinol resin (PF), polyurethane (PUR) and EPI (emulsion polymer isocyanate) are the main adhesives used for mass timber products. The choice of adhesive depends on whether a light or dark seam is desired and whether the element is intended for indoor or outdoor use.
The glulam lamellas pass through a glue curtain which applies individual strings of adhesive evenly over the workpieces. Excess glue is collected in a tub and reused.
In the production of cross laminated timber, the glue is applied over the entire width of each layer with an application head with nozzles arranged next to each other. Simple application heads are used for the production of standard goods in fixed widths. More complex heads can dose the application quantity exactly. Sometimes sensors are also used to detect cut-outs, e.g. for windows and doors. Adhesive is then only applied where it is needed.