So we have several modern TIG machines in the shop, older Dynasty 300, newer Dynasty 350, Dynasty 700, and Lincoln's Inverter TIGs with adjustable output frequency.

We use the advanced controls all time... Asymmetric wave, extended balance control, variable output frequency, and of course pulsing controls.  I have yet to find an instance where any alloyed tungsten (other than Zr) would weld as well, much less better than pure tungsten when working on thin materials at low current levels.

We have used boxes of Ce-2, La-1, La-1.5, and La-2.  .040", 1/16", 3/32", 1/8".  Long taper, short taper, no taper.  No blunt, small blunt, large blunt.

Balance with EN from 60 - 95%, most commonly 60-85%.  Output freq from 60 to the maximum cycle rate of the power source, most commonly 100-200 cycles.  From equal amperage level on EN and EP to twice the amperage level on EN as EP, most commonly equal to 50% higher on EN.

Now these advanced controls make the alloyed tungstens weld much better than without them.  However, in all cases I can think of the same control settings made the pure weld better yet (again speaking of lower current levels on thin material, primarily .040", 1/16", and 3/32" thick).  The main reason being the arc would come off the molten tip of the pure well focused rather than flaring more and/or riding up the side of the alloyed tungstens.  Additionally, it seems the alloyed tungstens tend to erode slowly while welding which in turn leads to arc control / flaring problems that don't appear with the pure electrodes that always have the nice small molten area on the end.

So what I would like to know is how exactly can I realize the purported benefits of the alloyed electrodes, such as La or Ce, over pure?  I will provide a simple scenario:   Single pass horizontal fillet on a T joint.  1/16" 5052 aluminum (brushed both sides and riser edge filed flat).  5356 fill rod.  Looking for full pen at the root and no burn through, blistering, or suck back.  Now we do this all the time, but I have always found it to be a comparative ***** with La or Ce.  Can you recommend power sources settings and electrode size (La or Ce) and end prep that would make this easier than with pure?

Thanks