Surface Wrinkling

Surface folding occurs when the weld pool is turbulent and the flow cannot be controlled. Then the liquid surface layer tips over and forms this wrinkled structure. This is usually a sign that you are working with too much energy or wrong technique. The folds are not only an optical problem, they disturb the homogeneity of the weld and can later lead to cracks. You have to keep the weld pool calm and even, then the surface layer will lay down cleanly. Adjust your travel speed and heat input, then it will get better by itself.