Re: Starphire glass & bulb life

Judy Seigel wrote:

>
>A comment about fluorescent bulbs in particular tho probably all
>bulbs -- they are extra bright when new; in the first few hours
>they drop a lot, then the drop is more gradual over about 9000 hours
>-- or so it said in the Westinghouse (or Phillips, or whichever)
>book. If those BLB bulbs that took so much longer were very old,
>compared to very new BL, that could explain. However, my tests with
>bulbs of *roughly* same age, showed the BL about 25% faster than the
>BLB.
>

Judy makes a very good point about fluorescent tubes being extra
bright when new. I think that many wrong conclusions about printing
speed have been reached by alternative photographers who switch out
old tubes of one type for another type, say BLB to BL, or BL to SA.
If they observe a significant difference in speed, which is likely
with new tubes, the assumption is that the *reason* for the speed
increase was the type of tube. Been there, done that.

As I say, I made this mistake myself. When I first started testing
different types of UV light sources, especially tubes such as BL,
BLB, SA, AQUA, etc. I assumed that it was best to start with new
tubes. However, the results were so different from what one might
logically have expected that I concluded that a more accurate
representation of printing speed would result from *aging* the tubes
some 100-200 hours.

I learned a lot from the experiments, not least of which was the fact
that I did not really know as much as I thought I knew about testing
procedures. I also learned that I am in good company, since many
other so-called experts have made the same mistake. Not so
devastating I guess since no one usually calls them on it.

Sandy
Received on Wed Nov 16 22:50:47 2005