Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Mirror Silvering on fused quartz
Q. We are looking for a process for placing a silver electrodeposit on quartz mineral. Can anyone describe a first step for metallizing the quartz surface, prior to plating?
Craig Ingalls- Minneapolis, MN, USA
2002
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A. One way to plate your quartz with silver is apply electroless copper first to get a conductive coating. Neil BellRed Sky Plating  Albuquerque, New Mexico  2002 A. Craig, Anyone that makes or knows how to make glass mirrors can help you. Not too much of a secret. You use a silver salt (I believe it's nitrate) and a reducer (there are several) to produce an autocatalytic (self) deposition then plate for increased thickness. Obviously, surface cleanliness is a must. Bye, Guillermo MarrufoMonterrey, NL, Mexico 2002 |
A. Craig,
There are several methods to used to put down a silver seed layer.
One of the oldest is from Peacock labs where a silver salt and a reducing chemical are sprayed onto the surface of the quartz. This process is the sam process which used to make mirrors and works well.
It is also possible to use electroless copper or nickel to put down the seed layer. It is also possible to spray on a silver filled epoxy paint.
Once the seed layer is applied, pulse plating should be used to build up the silver thickness
Pat Mentone
St Paul, Minnesota
2002
Need silver plating of quartz tubes
2005RFQ: I would like to find someone that will silver coat the inside of a quartz tube. Can this even be done (4 mm x 6mm x 7" long)
Bob RichmondElectro-Optics - Ann Arbor
Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)
A. Hi Bob. Yes it can certainly be done. The mirror silvering process has long been applied to glassware. In glass museums you will see double-walled (like a thermos bottle) glassware of intricate shape where silvering has been applied between the closely spaced walls.
Luck & Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Coatings/platings for visible and infrared light mirror
Q. I am developing a light source for a machine vision application, that includes a metal reflector surrounding a quartz-halogen lamp. This lamp holder/reflector assembly will most likely be manufactured from an aluminum alloy, as yet an unknown composition. I need to create a mirror surface on this reflector that creates as much light reflection as possible, across a very wide range of wavelengths: visible to near-infrared light (400 to 2500 nm).
I know polished aluminum has a very good reflectance spectrum in this region, but will it degrade with time? (Oxidation and exposure to a very hot light source). Would it be better to coat the aluminum to provide a flat and long lifetime spectral reflectance? Silver is good, but what about nickel, nickel+chrome? Any other good reflection materials?
This mirrored surface will be on the inside of a long tube reflector with a 'C' like cross section. But this assembly will also produce a lot of excess heat that will be absorbed by the reflector. What can I coat the OUTSIDE of the reflector with to provide the greatest heat radiation? Most computer / electronic heat sinks are black anodized aluminum I think. I'm not sure about the manufacturing process yet, but if for example I electroplate the entire reflector, will the mirror coating on the outside reduce excess heat radiation? Would it be optimal to have a black outside, and a mirror inside?
Any advice, suggestions appreciated.
image scientist - Riga, Latvia
January 13, 2010
A. Hi, James. Nickel and nickel-chrome are not good reflectors -- they absorb too much heat. Rhodium plating should be excellent and tarnish-free because it is a precious metal.
If you stick with aluminum, the purer the better, and electropolishing is a bit better than brite dipping. Then a thin anodized layer.
I think a black outside would be good, but there are high emissivity coatings that would be better than black oxide. Please search the site for emissivity. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
January , 2010
Nickel plating for high power water-cooled silver mirror?
Q. Hi. I am going to make a silver mirror over a quartz substrate using vapor deposition technique. It is going to be subjected to high power flash lamps and work in DI water flow for cooling purpose.
What do you suggest to protect the silver layer from oxidation, corrosion and peeling off by water flow?
Is it good to plate more silver over the deposited silver layer and then plate a thick layer of nickel over it?
I have seen such a mirror with a layer of copper in between (I am not sure about any other layers). What is this copper layer for?
Thank you in advance.
- tehran iran
August 1, 2020
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