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Dichroic glass


#1

G’day. I have been seeing comments on dichroic glass. Now I
thought that dichroism simply meant a transparent material which
has more than one refractive index depending on the presentation
of a light ray to a particular crystal plane - emerald is an
example I have in mind, where the emergent rays can be bright
green or an olive colour. But I get the impression that the
dichroic glass referred to in this forum isn’t quite like that.
I have seen glass which is still transparent but has a kind of
metallic blue, yellow or magenta appearance on the surface. Is
that what is meant? Enlighten my darkness I beseech thee…

    /\
   / /    John Burgess, 
  / /
 / //\    @John_Burgess2
/ / \ \

/ (___)
(_________)


#2

John Burgess,

Two places on the internet will answer your question about
dichroic glass:

http://www.uroboros.com/
http://www.dichromagic.com/ From Surbhi


#3
But I get the impression that the
dichroic glass referred to in this forum isn't quite like that.  
I have seen glass which is still transparent but has a kind of
metallic blue, yellow or magenta appearance on the surface.  Is
that what is meant?  Enlighten my darkness I beseech thee

John:

Yes I believe what you are describing is dichroic glass. As I
understand it, dichroic glass is made in a vacuum in which metals
are vaporized and deposited onto a glass surface. When fused to
other glass with this deposit layer sandwiched between two layers
of glass then a black opal like effect is achieved.

Kenneth Gastineau
@Kenneth_Gastineau1


#4

G’day: I just got this signal bounced back to me; I suspect it
might have been due to the Orchid shut-down (I got withdrawal
pains) so I send it again 'cos I want to know; but please excuse
me if you’ve seen it before.

originally written by John Burgess on 06-Aug-97 ***

G’day. I have been seeing comments on dichroic glass. Now I
thought that dichroism simply meant a transparent material which
has more than one refractive index depending on the presentation
of a light ray to a particular crystal plane - emerald is an
example I have in mind, where the emergent rays can be bright
green or an olive colour. But I get the impression that the
dichroic glass referred to in this forum isn’t quite like that.
For a start I have always understood glass has no crystal
structure; it is technically a liquid. I have seen glass which
is still transparent but has a kind of metallic blue, yellow or
magenta appearance on the surface. Which I thought was due to a
precisely deposited coating (similar to photographic lenses) Is
that what is now referred to as dichroic? Enlighten my darkness,
I beseech thee… And Cheers,


#5
G'day.   I have been seeing comments on dichroic glass.   Now
I thought that dichroism simply meant a transparent material
which has more than one refractive index depending on the
presentation of a light ray to a particular crystal plane -
emerald is an example I have in mind, where the emergent rays
can be bright green or an olive colour. But I get the
impression that the dichroic glass referred to in this forum
isn't quite like that. I have seen glass which is still
transparent but has a kind of metallic blue, yellow or magenta
appearance on the surface.  Is that what is meant?  Enlighten
my darkness I beseech thee.... >>

I’ll give it a shot, John, tho’ I’m sure there are others more
experienced hanging around the Forum.

I was told dichroic means two colors and your scientific
explanations sounds real close. If you look at these fused glass
pendants, beads, cabs, etc. with the light shining through them,
they will be different in color than if the light is being
refracted off them.

I don’t suppose you get Lapidary Journal on the other side of
the globe, do you? There was an article in the August issue that
had some photos that would give you a good look at what can be
done with it.

My 3-hour workshop taught us how to fuse together different
colors, even different textures of glass getting some very nice
and often vibrant effects. Say, you might start with a bottom
sheet of opaque black glass, put some bits of metallic colored
glass on top of that and lay a clear layer on top of that. After
firing you have some nice shiny colorful glass with “depth” to
it.

Hope this rough explanation didn’t add to your questions!


#6

As I understand it, dichroic glass is made in a vacuum in which
metals are vaporized and deposited onto a glass surface. When
fused to other glass with this deposit layer sandwiched between
two layers of glass then a black opal like effect is achieved.


#7

If you want to see a sample of dichroic glass by sarah
creekmore, plsease go to
http://www.erols.com/slist/gary/creekmore.jpg

Sara Creekmore is a nationally recognized name in the field. I
don’t use her stuff in my own work because most of it deals with
a theology I am not comfortable in using in my own designs. But
her work is good, the quality is very excellent, and her
merchandise is quite dependable.


#8
  I have seen glass which is still transparent but has a kind
of metallic blue, yellow or magenta appearance on the surface.
Which I thought was due to a precisely deposited coating
(similar to photographic lenses) Is that what is now referred
to as dichroic? Enlighten my darkness, I beseech thee......  

I believe that the discription above fits what is being
discussed. The dentest usually has lamps with lenses made of the
same material . … I believe the person who started using this
when lamping beads, used this product and discovered the
beautiful colors that can be had. . .


#9

I was told dichroic means two colors and your scientific
explanations sounds real close. If you look at these fused glass
pendants, beads, cabs, etc. with the light shining through them,
they will be different in color than if the light is being
refracted off them.

I stumbled upon a way of doing this many years ago while playing
with torch blown glass (beads etc.). If I remember correctly, I
mixed cobalt and copper oxide into the glass in sufficient
quantities to give a red-brown appearance when light was
reflected (not refracted – that has to do with light being bent
while traveling through glass) off the surface and a purple-blue
color when light shown through it. There is a famous glass bowl
in the British Museum that has dichroic glass (as defined
above). I believe that the reflection color was green and the
transmission color was ruby red.

Some other posts have mentioned a metalic-like surface on glass.
This is a coating that is applied to the glass, usually in a
vacuum chamber. This technique is used on most good telescope,
camera, and binocular lenses. Variations are often used on
darkglasses as well. It is not dichroic glass. You can achieve
simiar effects on blown glass by fuming with siver nitrate, but
probably wont get a very even coating.

Robin Casady
http://www.scruz.net/~rcasady/

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