Sovtek red lettering

[Wattever]

Has anyone else had the red painted lettering on Sovtek OP tubes vaporize? I just installed a new set into an amp, and the paint is fading, and redepositing itself as red powder around the base of the tube, even though the amp had always been upside down, IE the tube sockets were above where the lettering came from.

I haven't noticed any red plating, so I'm wondering if this is normal for them, of if I have yet another problem to track down. The amp had Sovteks in it when I got it, and they had no red lettering on them at all, but I assumed that it was something new that the old tubes didn't come with.

Anyone else run into the same thing?

[soundguruman]

when the oil from you finger is on the tube, and the tube is heated, a reaction takes place that speeds this process up.
Why are you operating the amp upside down always, prey do tell?
The tubes cool better with the base down.
And you will need to get the amp properly biased, so that it is running at the correct temperature. Just because the plate is not red, does not mean that it is correct.
Other than that, the materials are different and may flake off faster when heated, or overheated in the inverted position.

[demonufo]

Why are you operating the amp upside down always, prey do tell?

Um, COMBO, perhaps?

[Wattever]

Actually, I had the chassis upside down, because I was setting the bias, and then checking voltages. This whole red dust thing happened in probably less than 20 minutes of run time while the amp was idling, with no input. That's why it seemed so odd to me.

The bias is set at what seems to me to be a very tame 35ma (6L6WXT+@490V) so I couldn't really see why they should be running hot enough to vaporise the paint.

After all, if there's one thing the Russians should have down to a science, it's red paint.