Hello sk8bdr110, first off welcome to the forum. Stainless steels are susceptable to contamination/oxidation when they are unprotected above their reactive temperature. In short, if you are travelling too slowly with your weld progression and the heat input is high enough that the shielding gas is taken away from it before it has dropped below the reactive temperature that I spoke of, you will see issues with loss of the silver, gold, straw, pink, colors that will lead to the blue, black, and other less than desirable visual indications.
     There has been considerable discussion of what the various colors in stainless mean and depending in many cases who you are speaking with, their opinions will vary widely as to what point there has been a compromise in mechanical and service integrity.
     Personally I prefer to have the colors that are present before you reach the blue hues, yet that isn't necessarily always possible. A few tips that I will give might go like this: use an electrode extension that will allow you to keep the point of the tungsten as close to the actual weld puddle as possible without actually touching it, if you are using a gas lens, use flow rates that are slightly greater than those suggested for standard cups (try not to get too radical with your flow rates as an excess can cause turbulence that can actually induce atmosphere into the weld zone), you may want to lay back the travel angle slightly more than you have been, the more directly you point it into the joint the more you might concentrate the heat and penetration (this can be used to your advantage in some situations), sometimes more amperage and an increase in travel speed is actually better than less amperage and a slower travel speed (this may reduce the HAZ and allow for a more rapid cooling of the weld bead which can also lead to the color that you were hoping to maintain), using heat-sinks on the backside of a weld joint will also help with controlling distortion and overheating, thus helping with finished bead colors if you are trying to keep the colors that you spoke of. Experimentation and practice will likely lead you to determining what it will take for you to be satisfied with your end results. Try only changing one thing at a time and taking note of the results and don't rush into making changes after only trying something once or twice, give it a chance before trying something else. You mentioned that one of your instructors wanted you to use what might be called the "lay wire" technique, there is nothing wrong with that advice, at the same time it is not the only game in town either so try it right along with the other methods that you will likely be exposed to through other experienced welders, instructional tapes, or other sources of input. Personally I like the "lay wire" technique for pipe or open root applications and a "dab" technique for a lot of the other applications. Just a little bit for you to think about. Best regards, Allan

Roll your cup ,sometimes when walking the cup some people raise the tungsten when going side to side .This balls your filler wire and removes sheilding gas.When you learn to roll your cup your will go faster and you will not burn the pipe up . Also use a large cup with gas lens on stainless . On scd.10 i use a number large #12 with gas lens .

well in order to get a silver or base metal colour the weld has to cool down completely before it leaves the shielding gas. usually this is not 100% possible at welding parameters that make nice welds.

Stainless cools slow so if you get a nice amount of heat to melt things in and get good wetting chances are the weld will be too hot when exiting the shielding and it will produce the pretty colours. Not a practical solution... not acceptable for most welding work, but it is possible to drag a bead which helps point the gas backwards  to shield the weld longer.

Fast and "relatively" cold with a small bead technique wise is what you want, although that's probably not in the best interest of production times. When fusing 18-22Ga I could consistently get a pure silver colour because the heat input was so low and travel speed was relatively fast. However if I'm putting in the root pass on stainless pipe you couldn't use such low settings and still get adequate penetration and fusing.

More pratically a trailing shield is the way to go to still get good beads and good amount of deposition if you're doing thicker work. Depending on the code requirements various levels of oxidation are okay and a light straw colour is acceptable for general work. Somehow over the years a lot of welders, weld supervisors and welding inspectors have got the notion that "straw" or even the rainbow effect is more desireable than just silver alone.

Finally it should be noted that any colour comes from chromium oxidiation and that it reduces the corrosion resistance of the weld. It  MUST be removed if you want to regain the corrosion resistance of the metal.

not my welds looks a little hot to me or a little slow