What do your candles look like? With NG, it is hard to tell if you are running a fuel-rich flame because the tips are white instead of yellow, and are a little harder to see.
For a neutral flame, you will want to run your candles 1/4" to 3/8" long and have tiny tips. The shorter your candles, the less tips. But again, it is hard to see them when using NG.
Oxygen is your friend. Fuel needs oxygen to burn completely. Oxygen does not deposit soot onto your glass. If your fuel is not completely combusted, like from too little oxygen, the carbon from your fuel will deposit onto your glass.
Also, Smiley is right about how the fuel is not completely combusted close in to the torch face. So, make sure that you are not working right off the face of the torch. It is combusted more completely a couple of inches from the tips of the candles. So, try working about 3" to 4" or so out from the face and see if that helps.
The slower yuou work, the further out you will want to stay. As you get faster, move in closer.
And about the Lynx... The Lynx does not run at 1/4 psi fuel. It needs about 2- 2.5 psi to run properly.
I hope this helps.
PS Are any of your candles excessively longer (like by at least half the length) than any others, or are they pretty even?