Hi, recentely i recovered two T12 40W in recycle center, but the etches faded away.
Because one of them is very strange (it have metal strip and half is more coated with phospor), but i can't
see the etch, is there any way to recover it?

I believe some people rub powdered graphite and it catches in the writing, thus revealing it. If the etch was simply ink, then there is little chance of getting it. I have also found very worn etches on which I breathed in order to steam up the glass. If done in very bright light (sunlight works best) you can see the etch on the phosphor below on the other side of the glass. Wouldn't work on inside etches or on clear lamps, though. Hope this helps.

Some etches glow under UVA. Others can be repainted with pencil but you have some risk of scratching off the etch too

 I have recover the etch of a 50 year commemerative lamp so i can take a photo
  what I did took a soft lead pencil. scrap the lead into powerdered graphite dust with a razor blade
 on to a sheet of toilet paper. wipe over it few times to see if it brings them out. hope fully that works out for ya.
 

on vacuum tubes i put it in the freezer a while.
moisture will condense on it and sometimes show up the faint markings.

uff, i tried to recover, but they seems to have no brand