Purpose of Kodak Flashed Opal glass

[gorbas]

Many decades ago I heard of Kodak Flashed Opal glass. As many years took me to find one. Finally last Sunday on local Camera swap meeting I got a few of them. Beside diffusing collimated light coming thru condensers and nice and diffuse backing for copying negatives and slides, what other purpose it had? They are not optically perfect as I was expected. There are some wrinkles and other optical imperfections on them.

 

[AgX]

What does "flashed" mean in this context?
That it is a two layer glass? (Pigmented layer on plain glass)

But such should be called "fused".

 

[Nodda Duma]

Flashed means one side is opal glass, not both. If you google opal glass, you'll find some info on how it's made.

Opal glass is pretty much solely used for a cheap, diffuse, uniform (almost Lambertian) light source. There are better ways to get a Lambertian source, so opal glass has kind of fallen out of favor for scientific use.

 

[gorbas]

Thank you Nodda Duma for explanation!
AgX: Yes, there are 2 layers of glass bonded together. Total thickness is 3.4mm and opal layer is maybe ~0,4mm

 

[AgX]

I am surprised they were sold in 12pieces packages.
Who would need that amount?

 

[gorbas]

Well, you buy one package per life. I got left over, 5 of them. Enough.

 

[Nodda Duma]

I am surprised they were sold in 12pieces packages.
Who would need that amount?

Clumsy engineers

 

[M Carter]

Hello Gorbas, nice to see you -

I bought a 5x5" Kodak opal from eBay; they're also nice for contact printing film to make darkroom masks. Heavy enough to hold the film down, and none of the texture that things like duratrans can transfer though.

I wonder if the imperfections you see are from long storage or something? I'd assume the stuff was optically pretty sound back in the day?

 

[gorbas]

Hi Michael, nice to see you too! On one plate, opal side has texture similar to painting brush stroke, psychically wavy texture. Most likely diffusion is not affected but optical image will be. I tried to photograph it with my phone but is almost impossible. Have to use right tools

 

[MattKing]

If only I had known....
I too was at the show/swap on Sunday. Would have liked the chance to actually meet you Goran.

 

[gorbas]

Matt, we should have gathering of Vancouver APUG chapter on next Camera swap, October 2?
This time I have seen Dennis (dances_w_clouds) and a few other people recognized my ad on the table for
8x10 copy camera as they have seen it here or on Large Format forum.

 

[AgX]

On one plate, opal side has texture similar to painting brush stroke, psychically wavy texture. Most likely diffusion is not affected but optical image will be.

What optical image?
There should not be any other image than the image of that wavy surface. A reflected image, there should not be any transmissive image due to the diffusion of the milky layer.

 

[gorbas]

Of the 5 sheets of Kodak opal glass I got, this one has the worst texture of the opal layer.