Dichroic glass

[Peter A. Neary]

Sorry if this is a bit hair-brained. But my father seems to think he should
be able to make dichoic glass using a tungsten filament to vapourize the
coating material in a vaccuum chamber. Is he right? If so any information
would be greatly appreciated. What coating material/ oxides? Vacuum
pressure? Does the vacuum chaber need to be heated? Why?
Thanks, Peter.

[Peter A. Neary]

I don't know if my last post went through but here it goes again. My father
seems to think that he can make dichroic glass in his shop using a vacuum
chamber with a tungsten filament to vaporize the coating material. Is he
right? If so, any info on how-to (ie.coating substances, etc.) would be
greatly appreciated.

[Andrea Streicher]

If I were you I would call Coatings By Sandberg and ask for Howard. He is
really a nice guy and knows his business.
CBS has ,in my opinion,the best dichroic coatings available.
I am sure he would tell you the truth about what's what in the dichroic
coatings world.
--
Regards,
Andrea Streicher
Striker Studios

"Peter A. Neary" <pne...@powersurfr.com> wrote in message
news:PUXn5.8899$T5.1...@news1.rdc1.ab.home.com...

[jf...@my-deja.com]

I'm pretty skeptical that your dad could pull this off. Sandberg once
told me what his setup cost; I don't remember the exact figure but it
was in the hundreds of thousands of $. Also Andrew Brown once told me
that if the chamber were to be breeched it would certainly be
catastrophic--he compared it to an airplane at high altitude--you could
get sucked in!

There's a reason you can count the art glass coaters on one hand. In
addition to all the other obstacles it takes a high level of technical
expertise. And even though these are nice guys I'm not sure they'd be
eager to share the trade secrets.

On the other hand, I heard about a glass blower down south (N.C.?) who
coats his finished pieces in his own dichro vacuum chamber. So I guess
it can be done.

David.

In article <tJZn5.64$fj6.1...@news.pacbell.net>,

Sent via Deja.com http://www.deja.com/
Before you buy.

[Glenn Woolum]

I looked into this myself once. What I found out is that (at least for me)
it is much more cost effective to buy it already made. The bare minimum for
the equipment is an investment of about $75000.00 (not the best equipment
either). There is also a lot of knowledge about thin film deposition that
needs to be gathered as well as the tremendous amounts of time needed to
create desireable results. When you add it all up, I'd rather pay someone to
do it for me.

If your father is a scientist, he might be able to create conditions that
will cause some deposition to occur on glass, but the question is whether
the end result would be useful. If not, you'll still end up spending large
amounts of money and time to perfect your TF deposition process.

--

Regards,
Glenn Woolum

[Thee Monk]

Monkey bacon served cold with a side salad, is a tasty treat for a hot afternoon snack.

[anonomys]

Instead of talking to a glass person about this try to find folks (there are thousands) involved in wafer foundries. ie intel, amd,motorola,ibm,bell labs ect.  They can probably without violating the terms of their contract explain to you the process. Metalic vapor deposition is a little different then ion implant. Can be done cold, and the layout isnt what Ive seen quoted here for $$.  But true dichroic is going to be tricky just with vapor. One of the computer fab enginneers might be able to help. I call it Industrial Incest when the Art meats the Industry.

Kraig
hotg...@madriver.com

Thee Monk wrote:

When Thin Layer Coating in Clackamas, Oregon was in business, the owner
told me that each of his three chambers cost around $600,000 each. But
then, my neighbor told me he was a heavy engineer when in fact he was
just an Erector Set fan.

---

[Tim Lewis]

The short answer is yes, it is possible. I know someone who bought a small
surplus sputter chamber and made his own dichroics but it does not stand up
to the temps of fusing. It also cost him big bucks to get the assistance of
and expert to get it to work.

Sputtering is a different (cheaper) method but has similar results - just
not for those of us who cook it. Let un know what happens.

Tim

[Neon John]

Tungsten is a poor choice. Hard to control. A good metal for your
first experiment would be titanium. Wire is available from Strem
chemicals (http://www.strem.com). Titanium yields very pretty
rainbow coloration. Of course, it will take some refinement and
experimentation to achieve the nice solid colors that commercial
thin film outfits produce but it's doable.

I've done thin film deposition in my shop using little more than a
modified pressure cooker, a low voltage power supply and a high
vacuum system. The pressure cooker is modified by sealing all
openings using high vacuum techniques (welding preferred),
substituting a Viton O-ring for the gasket (lower outgassing at
vacuum), adding a view port (cut a hole, high vac epoxy a hunk of
thick glass over it.) and bringing two power leads in through
homemade vacuum feedthu fittings (compression fittings with wire
potted in the opening using high vac epoxy.)

The high vacuum stuff (mechanical pump, diff pump, ion or cold
cathode gauge, fittings, etc) can be had used at Duniway Stockroom,
http://www.duniway.com. Figure $2k for this stuff.

Here's roughly the procedure.

Attach some titanium wire to the electrode on the pressure cooker
lid.

Chemically clean the glass using lab detergent (alconex
recommended), then caustic soda followed by conc nitric acid. Bake
@ 250 deg F for a couple of hours.

Place in pressure cooker, held off the bottom a half inch or so with
glass beads or some other heatproof, non-porous substance.

Close up the chamber and start the vacuum system. Optionally, heat
the chamber on a hot plate to oh, 200 deg or so. Not too high or
the O-ring outgases. You should achieve 10 E-5 Torr vacuum. If
not, look for leaks, outgassing components, etc.

Valve off the vacuum chamber and bring the pressure up to about 3
Torr using dry argon. Establish a plasma discharge in the chamber
to further clean the glass. I do this by coupling a magnetron from
a microwave oven through the viewport. The entire chamber will
light up with a blue glow. You should see the pressure rise a bit.
After several minutes of plasma cleaning, open the vacuum valve and
bring the chamber back down.

Valve off the vacuum to keep vaporized metal out of the vac system.
Apply current to the terminals so that the titanium wire heats
enough to have a significant vapor pressure. This takes "a few"
(less than 12) volts at several tens of amps. I use a large
unregulated DC power supply and a variac. The proper temperature
must be achieved experimentally unless you have an optical pyrometer
(and used a sapphire window instead of glass.) The brightness level
of a light bulb operating about 30% undervoltage is a good starting
place.

When the titanium is hot enough, it evaporates and the vapor travels
to all corners of the chamber. It condenses to a thin film whenever
it touches a cool surface. It coats all surfaces in the cooker but
most of the heavy vapor coats the glass right under the wire.
Again, experimenting is necessary to determine how much time is
needed for each deposition.

A dichroic coating is made up of up to 30 or so layers of thin films
separated by dielectric (oxide) layers in between. (Very greatly
simplified) The spacing is 1/4 wavelength of the color you want to
reflect. In this simplified procedure, you're laying down metal
layers. You have to repeat the vaporization procedure for each
layer you desire to lay down. With titanium, only a few layers
yield interesting effects.

To achieve an oxide layer in this application, you can admit some
oxygen to the chamber and then establish another plasma discharge.
This will form atomic oxygen which oxidizes the surface of the
titanium film. Again, much experimentation is required to perfect.

If you're really interested in this, I suggest that your first step
be to buy the book "Handbook of Thin Film Technology" ISBN,
0-07-039742-2. Sucker cost me $104 back in '92.

Lastly, Several years ago, I briefly chatted with a couple in
Atlanta who were doing Dichroic glass in their basement (or at least
had the equipment - not sure how well it was going.) I have the
name of Dave & Sherry Moser in Norcross, Ga. Sorry, don't have a
phone number. If you want to do some digging, you might look them
up and have a chat.

John

--
John De Armond
johngd...@bellsouth.net
http://personal.bellsouth.net/~johngd/
Neon John's Custom Neon
Cleveland, TN
"Bendin' Glass 'n Passin' Gas"

[jf...@my-deja.com]

John, that is the single most valuable post I've ever read on this
group. Thanks Buddy,

David.

........................................................................
.

In article <39AB3FE0...@bellsouth.net>,

[Neon John]

"Peter A. Neary" wrote:
>
> Sorry if this is a bit hair-brained. But my father seems to think he should
> be able to make dichoic glass using a tungsten filament to vapourize the
> coating material in a vaccuum chamber. Is he right? If so any information
> would be greatly appreciated. What coating material/ oxides? Vacuum
> pressure? Does the vacuum chaber need to be heated? Why?
> Thanks, Peter.

Tungsten is a poor choice. Hard to control. A good metal for your
first experiment would be titanium. Wire is available from Strem
chemicals (http://www.strem.com). Titanium yields very pretty

rainbow coloration, even in one coating. Of course, it will take