Every sealant application requires one extreme important accessory, the back packing rod. The back packing rod assures assures that the sealant just bonds to 2 sides and not to the backside of the treated joint to assure the so called “2-sided adhesion”. If the sealant would also stick to the backside of the joint, the performance is not guaranteed and joint breaks as well as delamination can happen. In the same time is the joint depth controled with the right chosen back packing rod diameter.