Dressing Tungsten Electrodes

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I have read read and have also been told by instructors that to dress tungsten for Al GTAW, use DCRP and use a piece of copper to ball the end. I have used this method and it seems to work well but I have recently been told that using copper to dress the electrode can cause contamination of the weld especially with some types of tool steels. Which is correct and I dont really weld any tool steels but which ones if I were to weld them?
Reply:The technique you have mentioned would be one of several approved methods for AC GTAW welding.  This is used with Aluminum and Mag.   Steels, including stainless and tool steels will use DC with straight polarity and a pointed tungsten like a pencil point.   This is the proper point for GTAW DC used on steels.IF it Catches...Let it Burn
Reply:Originally Posted by TxRedneckThe technique you have mentioned would be one of several approved methods for AC GTAW welding.  This is used with Aluminum and Mag.   Steels, including stainless and tool steels will use DC with straight polarity and a pointed tungsten like a pencil point.   This is the proper point for GTAW DC used on steels.
Reply:i too use the point.  i think copper does contaminate the point a little
Reply:Originally Posted by prop-doctori too use the point.  i think copper does contaminate the point a little
Reply:Originally Posted by zapsterwell said  but myself?i use a pointy tungeston for whatever i'm doing..even on aluminum with a/ci just let the ball form naturally and when it starts to get too big..back to the grinder........zap!
Reply:I too use a pointed 2% for just about everything as well. Seems that you can control the arc and puddle much netter than with a balled up tip. I also use tri-mix from DiamondGround, but they do not wotk too good on aluminum Tony
Reply:I use 2% thoriated with a nice axial-ground point when welding stainless or mild steel. I tried it on aluminum and it doesn't seem to work as well. Lincoln recommends pure tungsten on aluminum and that's what has worked best for me. I just let the ball form naturally due to the AC.
Reply:if you're gonna  ball the end , try doing it with a piece of stainless steel, not copper, if you're afraid of contamination. and, it does it quick, using dc positive .  and, for heavens sake , don't be afraid to experiment a little . ( on scrap, of course )[SIZE="5"Yardbird"