Welding Tips and Tricks

I new to tig welding for the most part. Most of it has just been practicing, I eventually want to build a chassis for a old car I have. But I want to have it down pat before I do. Here is what I have a question about. I have a HTP 221 Invertig...Have it set on 90 amps. about 1 sec pre flow....and about 13 seconds post flow. 2% red 3/32 tungsten ans 1/16 ER70s2 filler. .083 tubing. So far I have learned just to let the torch rest in your hand and not have a death grip on it, I think that has been the single most thing that I have read and applied that when I was done was like wow....big difference. Kinda just roll with your thumb to keep a good torch angle. Here is what I am struggling with. When welding a joint....I get all the scale off....wipe it with acetone...wipe the filler rod. It all real shinny. No gap at all, I put about 4 tacks on it. I then can weld about 1/4 of the joint and from the ripples not being perfect it looks really good and shiny. For me looks really well, I can flip it over and weld another 1/4 of the tube and it does pretty good. Now here where it kind of goes south, When I flip it back over and and well from the 1st 1/4 to do another 1/4 of the tube...The welds start to be grey. I know it heat related.....So I assume my weld technique at the moment is suited for cold metal, After the joint gets some heat in it they turn grey. So with that being said,...Is that the normal way to weld a joint....weld about half of it and let it cool and come back to it. Or is there a adjustment I can make to weld it all in one sitting. When I start I go all pedal....then back off just a tad. But when it goes grey I have tried backing off to a point where I know it to cold cause I have a hard time maintaining the puddle. I can weld half a joint....walk away and come back and finish it and it all looks good....just struggling after it gets heated up. Thanks for any advice I get,

If you were fabricating a frame then you could skip around letting the joint cool before going back to finish.

What is the tube diameter?

Did you clean at least an 1/2" back on the ID as well?

I have a few different sizes. 1 5/8" .083 is what I have been practicing on. When I ordered it I stayed with the same all thickness until it was smaller than 1" then I went with little lighter stuff. As far as cleaning the inside I actually do as far a my finger will get in there. I thought about doing the whole pulling a string thru it with a shop towel drenched in acetone thru it. Cause It awful nasty don in them tubes.

My take on it, on 4130, I wouldn't want shiny. Shiny means it cooled down quick before the argon dissipated away. Quick cool-down of the weld bead on 4130 is not something that I would want, for worry of producing some martensite in the weld joint. The only way I would accept shiny is if I was using a trailing shield so I know the shiny came from a extended argon shielding + slow cool-down, and not fast cool-down, but that's a whole 'nother endeavor in and of itself.

But if you're not worried about it, then simply letting it cool would help out with the bead color/appearance. You can also do my braided copper wrap trick. If it works on titanium, it will work on steel.