Conductive paint for plating on plastic, flowers, etc.

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Plating on glass

Q. Dear specialists,

This web-site database contains a lot of questions/answers on the plating the metals on the glass. But restrictions of my task force me to ask about this again. For laboratory research I need to make the inner surface of fused silica capillary (360 µm OD, 100 µm ID, 0.5 m length) conductive. In literature and on this web-site I have found a lot of information about metal plating on the glass. But I encountered great problems when tried to realize any of the methods described.

The capillaries are covered outside by polyamide protecting film, therefore plating process cannot be hot, to avoid the film destruction. The inner diam is so small and the length is so big, that it is impossible to use vacuum deposition. The silver mirror having good adhesive property and strength, which could be created without any problem on the outer surfaces by two-nozzle spray, cannot be created at the inner surface (I tried to reduce the speed of silver deposition by diluting and lowering pH in order to allow solution to fill the capillary before the silver starts to deposit. But silver layer never appeared to be strong and adhesive and always exfoliates and clogs the capillary).

I also cannot create the tin oxide film, because this process needs too high temperatures.

Now I try to plate the gold, but experience the same problem - gold layer is not adhesive. My current process includes:
1) glass surface etching by HF,
2) sensitizing by NiCl2/borane-tertbutylamine reducer (not by SnCl2/PdCl2) - similar, but not equal to as described by Feldstein in US patent 3993799 (1975), and
3) plating in KAuCl4 + borane trimethylamine mixture, pH=12 (adjusted by NaOH) (similar although not equal composition to as described by Burke et al, US patent 4142902, (1979)). Temperature is always room temperature. Rinsing in distilled water is done after each step. For first experiment I try to plate on the glass stick, not inside the capillaries. I use double distilled water for solutions preparation, not deionized water. I needed to modify the recipes from patents because I could not find all chemicals described.

What I do wrong? What is the main direction of search could you recommend?

I would appreciate for any comments on my question and also for any information how to make the glass surface conductive by other methods, different from metal plating?

Sincerely,

Sergei Aksyonov
Arizona State University - Tempe, Arizona, USA
2001

Q. Dear Tom Pullizzi,

Now I need to make conductive (only from inside) fused silica capillaries only for laboratory needs. I didn't think about inventing something new, but I feel I go that direction.

You are right, there are a plenty of patents about the electroless plating. I searched through several dozens of them. But close view reveal, that all of them use two-three basic approach with slight modifications.

Particularly, I didn't found any information about good one_solution method for silvering. All of them use two sprays -- this is because of the demand that silver salt and reducer must meet together only on the plated surface. Really, if one places two droplets (silver salt and reducer) on the glass and slowly connect them, then excellent bright silver appears on the boundary between two droplets, and never under the droplets. The sludge is formed in the volume of mixed silver salt+reducer deposits on the glass, making the growing silver layer (formed under droplet volume) porous and non-adhesive :-(. This is an essential of the two-spray method.

For my purpose (thin capillary) I essentially need one-solution method. It should contain some sludge inhibitor, which nevertheless allows silver to deposit on the glass.

Actually I found one well described one-solution silvering method in one book on glass blowing from 1950's, but close analysis showed, that sludge effect is overcome by thick silver deposition, thus making silver layer strong enough, although allowing some sludge to be incorporated in the layer. This will not work for me because capillary is too narrow.

Feldstein in one his patents describes the additives (Pb, Sn, etc. salts) which, as he claimed reduce the sludge formation. But nevertheless he used two-spray method. I tried this approach, but sludge appeared in volume before the silver began to deposit on the glass.

I see one way to overcome sludge-in-volume, this by adding some silver-chelating agent or micell-formator. But what could it be? It should be some substance, that covers the silver suspension particles as they appear and prevents their further growth but does not prevent extended silver layer to grow.

Sincerely,

Sergei Aksyonov [returning]
Arizona State University - Tempe, Arizona

Q. Thank you, Sara, but probably it is not what I am looking for. Nobody can spray inside 0.1 mm inner diameter capillary with length ~0.5 m.

Sergei Aksyonov [returning]
Arizona State University - Tempe, Arizona
2001

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Q. Dear Sergei Aksyonov,

I have the similar problem to coat the inside surface of the microcapillary to make it conductive. Also, the metal coating need to be thinner than 800 nm to make sure the visual light could go through. I read your question and all the follow-up answers here. Did you get any solution for your problem?

Any suggestion is welcome.

Limin Liu
Tulane university - New Orleans, Louisiana
2001

Ed. note: Our FAQ on metallizing non-metallic materials lists a number of different metallizing approaches and may be of some help to the readers. Although we have no experience to bear it out, in theory it would seem that a silver nitrate solution should be reducible electrochemically or with some sort of "time release" reducing solution to obviate the problems that Sergei is seeing with two-part silvering.

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Q. I like to produce/print as if a printed circuit on glass with transparent but optically conductive tracks for putting LEDs on it and sandwiching the same between two glasses by single component, UV curable adhesive to produce laminated safety glass. The same shall be electrically connected from outside to light up the LEDS. It would give appearance of LEDs light up without wire being seen from out side.
Second, application is to put invisible tracks on automobile glass/house glass to heat them up for fog control. I am looking for a method which can be employed without much infrastructure, comparatively safe in handling. economical in price. Can some one provide the solution with name and addresses of manufacturers of the involved materials
Thanks,

PURUSHOTTAM RATHORE
hobbyist and product designer - NASIKROAD, MAHARASTRA, INDIA
2007

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Plating on flowers

Q. I want to start new work in my city. I want to plate flowers; can you help me how I can plate on flowers?

Kamlesh Bhanvadia
for plating - Rajkot, Gujarat, India
March 25, 2011

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Conductive paint for plating on plastic

Q. Hello,
1. I would like to know which conductive paint is suitable for brush plating plastic, e.g. a remote control or a plastic laptop case. I saw many supplier selling silver or copper RFI, EMI shielding conductivity paint, can I use it?
2. Which surface resistivity level (after paint) is good enough for brush plating? <1 ohm or 100-1000 ohm?
3. After spraying conductive paint, can I brush plate immediately or is there any step in between?
Thank you for your time.
Regards,

To Minh
Hobbyist - Vietnam
November 17, 2011

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Q. I am a fledgling artist who is at his wits end trying to find a way to "electroform" organics. I have a really crappy rectifier (RioGrande 5-Amp, 1-20 V) which constantly fluctuates its output during my plating process leaving all sorts of bumps and blemishes on what invariably turns out to be a salmon pink plated object. What's worse, is that the water based colloidal copper paint I've been using often peels from organics (especially bone) allowing my copper sulphate [on eBay or Amazon]pentahydrate solution to eat away at the organics underneath, which eventually turns the entire piece puke colored.

I'm trying to find a faster and cheaper way to coat organics than expensive paint. I stumbled upon this:

Is it possible to use this process to coat organics (esp. bone) for copper electroplating/forming using an acid copper sulphate bath?

Dicky Brucks
Hobbyist - Oakland, California
December 6, 2011

Q. I've seen Aerodag G spray online (google it) and was wondering if it's possible to use this for an acid copper sulphate electroforming process. My main concern is whether the resistance of carbon based paints would be too much for the low currents used in electroforming. I have a water based copper conductive paint - works, but it leaves much to be desired in terms of detail, has a long curing time, and is fairly expensive. Also every organic I've tried winds up eventually being dissolved by the acid due to weak spots in the coat, ruining the bath.

Any advice would be awesome.

Dicky Brucks [returning]
- Oakland, California
December 6, 2011

Ed. note: The technical data sheet seems to imply that this product is not optimized for that purpose but that it's possible.

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Polishing Copper Plating on Plastic

Q. Good morning everyone,

Hope you are all staying sane during this very strange time. I am doing some chrome plating over plastic, it's for some small parts that I couldn't find anyone near me willing to plate for a reasonable price. I have 10 years experience barrel plating zinc and zinc nickel over steel, but I have never plated anything copper, nickel, or chrome.

To do this the process that was suggested to me was a conductive spray paint, copper plate, nickel plate, chrome plate. The problem I am having is that the copper plate comes out rough because the conductive spray paint creates a rough surface. I am trying to polish and smooth the copper plate using either a buffing wheel or a vibratory tumbler, I have a small tumbler. Unfortunately it seems that every time I try to tumble the parts it just removes too much of the plating and leaves the corners bare. I tried polishing the paint and that effectively did the same thing. I am plating small plastic knobs for a hot rod I am building since I couldn't find the original knobs in chrome. Does any one have any suggestions? Please ask any questions you need answered if it might help. I don't necessarily know what questions you may need answered. Thanks for all your help in advance.

Nick Brammer
This is for my 37 ford coupe - Surprise, Arizona, USA
April 3, 2020

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