I have been reading some historical threads here on Lighting Gallery about how the newer GE F15T8 lamps don't hold up. I've also seen some posts about some Sylvania lamps not holding up and going mercury starved, but those are the Octoron type (FO32T8). We all know Alto is trash (never saw a mercury starved Alto in high school).

My questions are as follows:

Are Osram Sylvania F15T8 Lamps good quality still?
Is the Osram Sylvania 4200K cool white halophosphor noticably different than GE's 4100K cool white halophosphor?
If Osram Sylvania lamps are not of good quality (or if color is really different), what brand is? Note I don't want to take the trouble to source vintage or even older lamp stocks.
What are your experiences with Halco and other off brands?

I get good life out of Sylvania, though very early on...for awhile may be super swirlers.

I get good life out of Sylvania, though very early on...for awhile may be super swirlers.

Okay, would using a manual start switch prevent that? All F15T8 lights in the house are push to start.

Manual start is where the most swirling happens. Trigger start is fine.  I have a made for GE Sylvania F14T12 that has well past 30,000 hours ( it's in 24/7 service) that has a lot of brown aging and typical thin Sylvania banding, but no black spots yet.

Manual start is where the most swirling happens. Trigger start is fine.  I have a made for GE Sylvania F14T12 that has well past 30,000 hours ( it's in 24/7 service) that has a lot of brown aging and typical thin Sylvania banding, but no black spots yet.

Thanks for letting me know about the issue being with preheating. We have three F15T8 lights in the house. One from the 1980s, one from the early 1990s, and my desk lamp. The two undercabinet lights have the original no-name lamps, my desk lamp has a 1962 GE lamp in it. The undercabinet lights will probably last a long time, but I'm a bit hard on the desk lamp with only running it for a few minutes at a time in some cases.

Another question I have with F15T8 lamps and this applies to all brands and all colors (except BLB where this effect is not visible). I see on the bottom of the lamp black spots (very tiny specs like dust) that are not mercury condensation throughout the length of the tube. Are these bits of the electrodes that get knocked into the arc stream and fall down or what are these?

If they are VERY tiny and happen away from the cathodes it likely is mercury.....but I would have to see the spots to tell. 

Powell

I really liked the Sylvania Designer Cool White (triphosphor 4100K) F15T8 lamps (there's also a Designer Warm White which is also nice, at 3000K) - they had these at Lowe's years ago, and I'm sorry I didn't buy more because they aren't sold there anymore. But sadly, the Sylvania lamps didn't last as long as I had hoped...I know I didn't get any more than 7500 hours, and probably less.

Most of my GE CW's (made in Indonesia) have held up well, but not exceptionally so. I have a few SP41 GE's on order, made in USA, and I have high hopes for those!