Abstract: The present invention is directed to a synthetic patch application method and device in which synthetic patching material is kept cool while it is mixed in a static mixing tube, prior to application to plywood panels. The synthetic patching material is kept cool by means of a removable cooling jacket that is installed to remove the exothermic heat of reaction generated during the mixing process. The cooling jacket is removable and reusable, and may be easily dismounted and remounted when replacement, adjustment, or repair of the static mixing tube is necessary. The present invention thus provides an improved method of repairing plywood panels using thermosetting resin-based synthetic patching materials in which waste is minimized and time between replacement of static mixing tubes is significantly extended.