The only time I have come across that yellow powder coating on the cup is when I have welded galvanized steel, but not sure about the tungsten. If its not galvanized the its some other sort of contamination. Hope this helps.
Spin,
Tungsten itself when not sufficently protected by shielding gas will produce yellow stuff. Assuming surface prep is good, Here are a couple of things to look for.
Argon flow too low. 15-20 cfh is a good place to start if there are no vagrent breezes.
Argon Flow too high. The swirling effect from too much argon will draw oxygen/nitrogen into the weld zone and make bad effects.
Clogged gas lens. If using a gas lens check the screen.
A damaged gas hose can suck air into it.
Poor technique. A radical torch angle or quickly lifting a hot tungsten away from the work will also contaminate it. Usually this results in simply blackening the electrode but if the thing is really hot you might see yellow too.
Contaminated gas. This one happened to me recently. The effect (visually) I experienced was poor color on stainless and complete inability to produce aluminum welds. A simple test is to make a sample weld on a clean piece of aluminum (it is more sensitive) and run an AC bead. If you notice a grey flake floating at the top of your pool and no etch at the toe of the weld where your used to seeing it, the gas is suspect.
Let us know how it goes for you
Lawrence
By -
Date 10-24-2003 14:22
I agree.Anyways how much is a good size argon bottle priced where you at or do you use a mix?......I would get a larger size bottle only when you need one for more applications when tig'n outside in the breeze!
Yes to wind, moving torch too much and too small lens. Thanks! I have have probably caused the problem. I use a 125 argon. I don't think the gas is contaminated. I have also notice needle fluctuation. I think the gauge sat for several years and is not operating smoothly.
From what I have seen, a yellow or yellow brown contamination can be caused by wet argon. Switch to a different cylinder can confirm.
Air or oxygen contamination often leaves tungsten black or other dark color.
Wet argon usually happens in the late, humid summer months. Cylinders are often filled months in advance, however.
As colder weather is approaching, an even slightly contaminated cylinder can cause problems when brought into a warm shop. Again-check with another known good cylinder.
Hope this helps-let us know how you make out
Good Luck
brande
