OT:Incandescent "soft white" bulb coating?

[Bob Masta]

Not exactly an electronics question, but I know some
lighting gurus hang out here. (Google hasn't been any
help so far.)

What is the stuff used as the coating on typical
incandescent "soft white" bulbs? I gather that
the non-soft-white are simply acid etched on the
inside of the envelope, but the soft white have
a separate powder applied somehow. What
is this stuff chemically? What makes it stick?
(It seems pretty fragile if you touch it on a
broken envelope piece.)

Thanks!


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

[Dan Ritter]

Not exactly an electronics question, but I know some
lighting gurus hang out here. (Google hasn't been any
help so far.)

What is the stuff used as the coating on typical
incandescent "soft white" bulbs? I gather that
the non-soft-white are simply acid etched on the
inside of the envelope, but the soft white have
a separate powder applied somehow. What
is this stuff chemically? What makes it stick?
(It seems pretty fragile if you touch it on a
broken envelope piece.)

Thanks!


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

All I know is that at least in flourescant lights they use different
shades of colored phosphors. I would imagine it's the same stuff but I
don't know.

 

[Sylvan Butler]

What is the stuff used as the coating on typical
incandescent "soft white" bulbs? I gather that
the non-soft-white are simply acid etched on the
inside of the envelope, but the soft white have
a separate powder applied somehow. What
is this stuff chemically? What makes it stick?
(It seems pretty fragile if you touch it on a
broken envelope piece.)

Doesn't stuck much... Even the broken pieces of filament swirled around
inside the bulb scrape off the powder. Hopefully it is just some talc,
gypsum, ...

sdb

 

[Jonathan Kirwan]

Not exactly an electronics question, but I know some
lighting gurus hang out here. (Google hasn't been any
help so far.)

What is the stuff used as the coating on typical
incandescent "soft white" bulbs? I gather that
the non-soft-white are simply acid etched on the
inside of the envelope, but the soft white have
a separate powder applied somehow. What
is this stuff chemically? What makes it stick?
(It seems pretty fragile if you touch it on a
broken envelope piece.)

The two commonly used finishes inside are etched glass (frosted) and applied
silica powder. As I said, the etched glass is known as 'inside-frosted' or
simply 'frosted' and results in the appearance of a glowing ball of light within
the globe. But silica powder is also used, and called 'soft-white' by most
major manufacturers. Although this cuts output more than etched glass, it makes
the entire bulb glow more evenly.

I hope this helps some.

Jon

 

[Bob Masta]

The two commonly used finishes inside are etched glass (frosted) and applied
silica powder. As I said, the etched glass is known as 'inside-frosted' or
simply 'frosted' and results in the appearance of a glowing ball of light within
the globe. But silica powder is also used, and called 'soft-white' by most
major manufacturers. Although this cuts output more than etched glass, it makes
the entire bulb glow more evenly.

I hope this helps some.

Thanks, Jon, this is exactly the sort of info I was
hoping for. Any idea what makes the silica stay on the
inside of the envelope?

Thanks again!


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

[Jonathan Kirwan]

Thanks, Jon, this is exactly the sort of info I was
hoping for. Any idea what makes the silica stay on the
inside of the envelope?

No, but I honestly haven't tried to fathom this in any detail. I don't either
have theory or experimental data to suggest much to me.

If you have a bulb to break open, see how well you can clean the substance off
with your fingers or wet rag. If it all comes off easily, then it is probably
surface tension and possibly some frosting on the inside to encourage that
tension and the particles are probably "very, very tiny." Otherwise, maybe they
"use something." But my bet would be that they would avoid depending on
anything other than the silica -- the more that is added, the higher the cost
(especially, as it is hard to find higher-temp materials and deal with
outgasing, etc.) and the more dangerous it may be in the home, as well.

But I just don't know.

Jon