Hello bozaktwo1, I believe that you will not realize the same appearance when comparing the two fillers. There are inherent differences between the two that will preclude that from happening. On numerous occasions there have been threads and posts here on the forum speaking of some of the differences betweeen these two fillers. What makes one(4043) more tolerant of centerline cracking and cracking in general, is the same thing that doesn't make it applicable in some cases(less strength). The lack of certain alloying elements in this same alloy also doesn't make it suitable for certain chemical environments or physical exposures. So when you are looking at using the 5356 you will be giving up some of the ease of application and physical aesthetics that the 4043 posesses, yet you will gain the feeding ability of the wire as it is stiffer than the 4043. This stiffness might allow you to use a smaller diameter of wire in some cases and allow for tailoring the weld bead size to more suitably match material thickness. As you have also stated you will see an increase in the "soot" that is present upon completion of the weld. I believe Al stated very well where this comes from, if my memory serves me correctly it is from the additional magnesium that is present and is vaporized in the arc. So, this may not go away even with a change in shielding gas. Hope some of this makes sense. Best regards, Allan