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Thread: Non-cyanide silver electroforming

  1. #1
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    Default Non-cyanide silver electroforming

    Hi
    I have seen a few older posts on this subject but none seem to answer my questions:
    I'm experimenting with electroforming at the moment and i have had a few good results with copper. I'm now starting to look at silver electroforming.
    I see Cooksons sell a silver solution suitable for electroforming but on reading up on the data sheet over at your new boss's site (Heimerle + Meule) I see that it is cyanide based, which is not ideal. (incidentally, I am amused that people wouldn't countanance using cyanide but will happily use sulfide based patina solutions, despite hydrogen sulfide (300-350 ppm) and hydrogen cyanide (100-300 ppm) having almost identical LC50 values!)
    So my questions are:
    -Does Cooksons sell a non-cyanide silver electroplating solution? If not I'll try some of the specalist groups out there- SPA plating seem to have one.
    -Are the non-cyanide silver electroplating solutions suitable for electroforming? I've not been them mentioned in this context when reading up on the subject- only as plating solutions.
    -Can you use a fine silver sacrifical anode with the non-cyanide solutions to avoid depletion of the silver from the soution (which I believe is the case with cyanide solutions, but correct me if I am wrong) They often seem to recomment a stainless steel anode.

    If I can't get no satisfaction I will try just silver plating my copper electroforms- which is probably the low hassel way of doing things!

    Thanks for your help.

    Matt
    Last edited by MMM Jewellery; 03-02-2014 at 03:49 PM.

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    I'm not sure of the answer Matt, but a number of the so called plating solutions are just dips designed to cover patches of wear on silver plated items, such as for instance cutlery.

    As they work electrolytically on base metals and cease to function as soon as the exposed surface turns silver, the coverage will be very thin and virtually an illusion.

    I do know that even thickly covered, electroformed items can be very fragile and need a decent shell. So yes, it's best to send them away to a specialist company.
    However you look at it, you won't survive breathing in hydrogen cyanide.

    Regards and welcome, Dennis.

  3. #3
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    Thanks for your reply Denis

    I am specifically interested in the electroplating solutions, rather than the electrochemical ones you mention- there are new non-cyanide ones out there now, so surviving hydrogen cyanide is not an issue anymore. I belive the counter ions are succinamide (recent) or sulfur based (available since the 70s but not used much) which have lower toxicity and should be low risk for hobbyists like myself- I guess I'm looking for someone with experience with the new generation of electroplating solutions.

    My experiements with copper electroforming are actually quite robust- I have exerted considerable pressure between thumb and fingers without flexing of the form- comparable to 1.2 mm silver sheet for instance. That took about 6 hr to build up, so silver should be doable too- maybe with a couple of light copper coats in the middle to generate alloys and help with hardness.

    Thanks Matt

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    Well, the if you find what you are looking for, I hope you will share your results with us here. Dennis.

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    I've just checked through my references and I'm afraid all I've got is on using cyanides.

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    A 12-year-old paper on CN-free plating solutions:

    http://www.istc.illinois.edu/info/li...s/rr/RR-94.pdf

    Not the most cheery reading.

  7. #7
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    Hi
    I have found this at metalfinishing.com from 2012, which in part answers some of my questions- you just need to look!! The product is from Dow and aimed at the electronics market but is probably ok for jewelery too- they have an photo example for decorative applications. Things have moved on in the past 12 years
    "SILVERON GT-101 Bright Silver, an improved cyanide-free silver electroplating bath, has been recently commercialized. A series of successful industrial installations have demonstrated that the silver deposits obtained from the SILVERON GT-101 bath are suitable for a very wide variety of applications. The present article describes the characteristics of the deposits from this cyanide-free, alkaline silver electrolyte in comparison to those obtained from conventional cyanide silver electrolytes.
    -Cyanide-free electrolyte
    -Suitable for barrel, rack and reel-to-reel plating applications; with a maximum applicable current density slightly lower than that of cyanide electrolytes
    -Highly stable electrolyte and consistent plating performance under production conditions
    -Fine grained, bright, white silver deposit suitable for a variety of applications
    -Good silver adhesion onto copper or nickel based substrates
    -Low contact resistance, excellent good solderability and ductility
    -Suitable for Al- and Au-wire bonding applications
    -Good reflectance at wave lengths between 400-450 nm; with evaluations for LED applications in progress
    -Increased deposit hardness, but comparable wear resistance to that of silver deposits from cyanide electrolytes

    They also mention:
    "Generally, soluble silver anodes are recommended for production, so that replenishment of metal salts during production can be avoided." - So that is one of my question answered

    Now all I need to do is track some down in a less than industrial quantities!! And have a peak at the MSDS. I might just have to do the electroforming experiment myself, but I cant see it being problematic. I'll see what other brands are available and post accordingly.

    Cheers Matt

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    Gah... Started writing a response then misplaced it. Oh well.

    I did see the releases on GT-101, but hadn't seen anything on how it behaves in thicker applications. Lower current density is a boon though.

    I was going to ask if you had a copy of the Electroforming book by Leslie Curtis - then I saw this: http://www.amazon.co.uk/Electroformi.../dp/B00DJFLN86
    Well, that's my laugh for the day...

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    Thanks- I have seen the book cheaper on the US site but I'll resist the urge for now to part with that much cash.

    Chestech seem to be the UK supplier of Dow plating solutions so i'll give them a call and see what sizes they do and if they'll sell to me. SPA plating also do a silver plating solution that is cyanide free but I will need to write to them to see what the make-up is and how it performs for electroforming-it would be a suitable option if I wanted to silverplate my copper electroforms at least.

    I was wondering if Heimerle + Meule do a cyanide free plating solution- do Cookson have access to their plating section or is that sort of integration not happening yet?

    Cheers Matt
    Last edited by MMM Jewellery; 04-02-2014 at 11:28 AM.

  10. #10
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    Hi
    I have heard back from SPA plating, but not yet from Chestech. The SPA system uses silver sulphate, I have also found Rio Grande do a solution called Midas that uses silver succinimide (it had only one poor review on-line, highlighting poor adhesion and dull finish). I have not yet got a Dow MSDS to see what they use.

    Here is the reply from SPA:
    Thank you for your enquiry. I have tested the solution with a silver anode and it works fine.For optimum results, the operating pH of this solution should be kept within the range 7.5 to 10 using a pH meter.You should be able to get at least 4 turnovers of silver (100g of silver per litre of solution) before the solution needs replacing.I have not tested it out for electroforming yet, but do not think that it will be suitable as the deposit is quite highly stressed.The best sort of solution for electroforming is one containing cyanide, but due to the high level of cyanide,we are not prepared to market such systems.

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