I like to create a purge dam with aluminum foil behind the area I'm welding. It helps hold the argon a bit longer. This is 1 1/4" OD x 0.035" tubing. You can see some light straw on this joint. I'm not too happy if I see blue. If I'm seeing blue where it is in your photo, it says to me that I am moving too slowly and the whole area is getting too hot. I like using 0.035" or 0.040" wire. One tip I can offer is to anticipate where your purge will get blocked by the bead. In other words, as you feed filler and the bead raises up a bit, you can get some turbulence behind the bead if your torch angle is a bit low. The bead blocks the argon. So I try to keep my torch angle at 85 to nearly 90 degrees to the joint. And as others have said, try to tighten up your dip spacing. I also suggest to practice on steel to save some money. Use your same gas lens and cup. If you can weld steel without color, you can get a lot closer to welding titanium without much color beyond light straw. Hope that helps a bit.


Titanium by Zanconato Custom Cycles, on Flickr


Backpurge by Zanconato Custom Cycles, on Flickr


Backpurge by Zanconato Custom Cycles, on Flickr