If you want a reflective white diffusing coating, the standard optical
product is called "Munsell White Reflectance Coating". It's real good
stuff and easily coated onto glass. I suspect you're talking about a
transmissive diffuser, though (the other side of a piece of glass
coated with this stuff will have only a tiny fraction of a percent of
light shining through!)

And a colleague who used to work in the lighting industry informed me
that most frosted glass used to be done with hydrofluoric acid etching,
although he was of the opinion that this is seen as environmentally
unfriendly today.

Tim.

On Wed, 07 Dec 2005 16:51:04 GMT, Ignoramus8325
wrote:

On 7 Dec 2005 08:48:37 -0800, Tim Shoppa wrote:
If you want a reflective white diffusing coating, the standard optical
product is called "Munsell White Reflectance Coating". It's real good
stuff and easily coated onto glass. I suspect you're talking about a
transmissive diffuser, though (the other side of a piece of glass
coated with this stuff will have only a tiny fraction of a percent of
light shining through!)

Yes, I want diffusive coating, not reflective.

And a colleague who used to work in the lighting industry informed me
that most frosted glass used to be done with hydrofluoric acid etching,
although he was of the opinion that this is seen as environmentally
unfriendly today.

I suppose I could rig something up to blast glass using my compressor,
but I was hoping to just find some coating.

You can't just sand blast it?

On Wed, 07 Dec 2005 18:05:43 GMT, Ignoramus8325 wrote:
On Wed, 07 Dec 2005 12:57:27 -0500, Goedjn wrote:

You can't just sand blast it?

I do not have a sandblasting setup of any sort, presently.

You know, if you and I lived a bit closer, I could see us hanging out
together regularly. I've got a blast cabinet in the garage...

One thing to think of - around here we have an outfit called "U-Spray"
which rents sandblast cabinet time by the minute. Inexpensive, they
have all the equipment, and you just pay a flat fee based on your time.
Might be a franchise?

Dave Hinz

mount the light facing up so it diffuses off of the ceiling...

that makes for a much gentler light

Mark

I suppose I could rig something up to blast glass using my compressor,
but I was hoping to just find some coating.

You can't just sand blast it?


I do not have a sandblasting setup of any sort, presently.

http://www.lonestarts.com/DripPan/SandBlaster.htm

At least from my own experience with MH fixtures, there's a good
chance the glass is tempered, designed to protect you from excess UV
and from showers of nearly-molten quartz if a bulb ever detonates. I
would not mess with the factory glass.

How hot does the outside of the glass get?

I used to have an MH in my garage that was a high-bay fixture in a
lower-height room, so I put an external diffuser on it, just cut a
circle out of one of those plastic diffuser sheets you can get at the
hardware store for 4-tube fluorescent fixtures, and mounted the
circle an inch below the MH fixture's glass.

--
is Joshua Putnam
http://www.phred.org/~josh/
Updated Infrared Photography Books List:
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