Blue Gas in Tubes - Why? Is it Bad?

If you go to the KR Enterprise site they will tell you this is bad and will give you the reasons (I don't recall). This is the only source where I have ever heard that this is negative but as they make tubes perhaps they have a point????

I use an ARC VT-100 with an LS-9 (ss) preamp. My tubes glow orange. I tried a Morrison ELAD (ss) preamp which made the tubes glow bright blue -I disconnedted it immediately.
I don't know if my tubes "had gas" but I wasn't taking any chances...

It is not a concern. If anything, it indicates a tube that has less gas in it. The elements may glow orange, but the blue is more of a fluorescent glow in the whole tube in the dark. See audioasylum--the tube guys there know this is true.

Try reviewing some of the guitar forums such as PRS forum and Fender discussion page, and Les Paul forum. There is a lot of info on tubes and your question. I have always had a blue glow in my power tubes Fender and Marshalls when they are biased properly. You can get some Bias Probes on ebay fairly inexpensively. Invest in them and you may see some improvement in the peroformance of your equipment. I am in the chicago area and what some of the shops want for biasing your tube amp is ridiculous. Not uncommom to pay $75.00+ in this market. You can buy a bias probe or equivalent for less. Most of the tube amp musicians/techs would love to respond to your questions, at least on the typical guitar amp power tubes. Go for it!

H-C, that's funny - I knew the Blue Glow was nothing to worry about for half my life when it came to my guitar amps and their 6L6's. Then recently I changed my stereo rig's amp from one using EL-34's, which never Glowed Blue in that amp, to a pair of mono's using 6550's, which 3/4 of year later are starting to exhibit it. Despite what I always "knew", I had to come and check it out again. That's the difference between guitar players, who'll abuse an amp until it cries uncle and not give a damn before it stops working, and audiophiles, who worry and obssess over every little thing despite everythings' working fine - Even if that guitar player and that audiophile happen to be the same guy! :-)