What does it mean if the weld metal surface has a striped pattern?

Question

I am not sure what is the best way to describe it, so here is a picture:

For comparison, the metal on the other side is smoother:

Answer 1

That’s not a weld bead. What you are looking at is body sealer. Typically that is applied by a robot in a weld seam, before the panels are positioned for welding. The vehicle panels are joined with spot welds. And when the vehicle is sent thru the paint ovens, that sealer expands and hardens up.

And after staring at this photo for a while it looks like this manufacturer does a post spot weld top apply. The results are essentially the same. The soft sealer hardens up in the paint oven.

And in that state you have a well built, waterproof sealed area. Note, there is a ton of water thrown up into the fender area when ever your vehicle is driven in a rain storm.

Those wavy lines indicate a bit of jitter from the original application robot. Nothing to worry about.