Experimental results of wavy metal interfaces obtained by explosive welding are presented and used to determine which wave forming mechanism occurred. It was found that for small collision angles (smaller than about 20degrees) the Von Karman or jet indentation mechanism occurs, while for large collision angles a straight metal interface is obtained. However, for metals with small shear strength values colliding at larger angles (larger than 30(degrees)) the Kelvin-Helmholtz instability mechanism may occur, leading to waves with relatively large length and amplitude.