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Coating glass capillary tubes with Ag

Hi,

I want to coat glass capillary tubes with silver. Could you tell me how to do it using Silver Nitrate solution?

Thanks in advance,

Amitabha S [last name deleted for privacy by Editor]
researcher - Lincoln, Nebraska
2004

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I believe there are a few companies that already do this for you. Do you require the inside or the outside of the capillary to be coated? I just ordered some internally silver coated capillaries from Doko Engineering (japan) as well as Polymicro. I don't know if this helps. If anyone can find decent literature on how to coat the insides of very small (50 µm bore) capillary tubes, I would be interested as well. If your interest is coating the outside of the tube, it is done in exactly the same way as old-time silver mirrors are made. I found a decent link here: www.make-stuff.com/formulas/mirrors.html
Thanks,
MPB

Michael B [last name deleted for privacy by Editor]
- Pittsburgh, Pennsylvania
2007

TO Amitabha and Michael. I am also interested in coating the ID of a 100 to 200u silica capillary tube. Polymicro only does 800u core and larger. I am concerned that a silver nitrate type coating does not have a strong adhesion. Your suggestions would help. I have done some silver hot melt process with both an oven and a gas flame with limited success. Any tips on how to get a reflective finish on the inside wall (the surface facing the outer wall) of a capillary tube would be helpful. Thanks,

Tony DeHart
- Richardson, Texas
September 2, 2009

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Hi,
The silver nitrate sticks very well. We have tubing made by Doko in Japan that has had numerous substances flow through it without flaking. There is an internal coating of some type (probably cyclic olefin polymer or silver iodide or more polyimide inside the silver coating) to protect the silver from damage and to make it more reflective (like a high-reflective mirror coating). I would suggest either buying them from Doko or making them yourself with the silver nitrate process if you don't care so much about the high optical transmission. These guys have done quite a bit of work on perfecting the deposition times and rates and such to make these things useable in CO2 laser delivery systems. Right now, we are working on making better tubes for visible transmission. The silver nitrate process can be found by searching for Yuji Maatsuura or his predecessor (Miyagi) in the literature. There is also some good stuff by James Harrington on making waveguides with silver or other liners.

Michael Buric
- Morgantown West Virginia
November 12, 2010