Electrochemistry Electrotyping

[solar_plasma]

Has anybody links, sources, knowledge about electrotyping? Good search items would also help.

 

[niteliteone]

Has anybody links, sources, knowledge about electrotyping? Good search items would also help.

Personally I have never heard the term before, nut when I typed it into google this is the first link;
http://en.wikipedia.org/wiki/Electrotyping

also from youtube is a description of a process;
http://www.youtube.com/watch?v=iTytvWs5nV8

 

[rickbb]

I used to do electrotyping, but we called it an electric typewriter.

 

[solar_plasma]

I used to do electrotyping, but we called it an electric typewriter.

Not my fault if the english term is misleading. :lol: The german term "Galvanoplastik" (means something like: Galvani style 3D shaping) makes more sense.

 

[goldsilverpro]

Since this thread has absolutely nothing to go with precious metals, I moved it. Please post stuff in the right place.

 

[solar_plasma]

GSP

Since this thread has absolutely nothing to go with precious metals, I moved it. Please post stuff in the right place.

I should have formulated it another way to make clear, that I am actually asking for a silver process.
This electrotyping has been used with gold and silver. In Germany it has been used in the silver manufacturing and industry since 1870. Using it with silver is exactly what I am interested in.

wiki:

The most celebrated may be their copy of the Jerningham wine cooler, which is a spectacular silverwork made in England in 1735 that has long been in the collection of the Hermitage Museum in Russia.[22] Many of these objects were made by Elkington & Co., which had an extensive business in electrotyped silver.
...
Electrotyping produces copies of objects that are not difficult to distinguish from originals, but this book contains a series of photographs illustrating the steps in making an electrotype of a gilded silver dish.
...
Galvanoplastic manipulations: A practical guide for the gold and silver electroplater and the galvanoplastic operator ... Based largely on the "Manipulations hydroplastiques" of Alfred Roseleur

Edit: I guess I have found, what I was looking for, though I had hoped to find something newer hobbyist-like:
Electrotyping; a practical treatise on the art of electrotyping by the latest known methods, containing historical review of the subject, full description of the tools and machinery required, and complete instructions for operating an electrotyping plant (1908)
https://ia700202.us.archive.org/8/items/electrotypingpra00partiala/electrotypingpra00partiala.pdf

 

[solar_plasma]

Okay, as far as I understand, electrotyping has been performed with cyanide electrolytes, obviously equal to nowadays silver plating in the industry - as far as I understood here on the forum.

I will not ask why, since obviously every common practice in this field has some good reasons. I assume this means, it can't be done with AgNO₃ as the electrolyte, - please correct me! If so, this little project is down.

Edit: This document explains why only complexes, such as cyanides or succinimide are used in silver plating industry:

Noncyanide Silver Plating (using succinimide)
http://www.technic.com/apac/sites/default/files/assets/pdfs/literature/Noncyanide Silver Plating.pdf

(using EDTA chelates without fully satisfying results though)
http://www.istc.illinois.edu/info/library_docs/rr/RR-94.pdf

(using 5,5-dimethylhydantoin, succinimide or various sulfxxxxx compounds)
https://data.epo.org/publication-server/pdf-document?pn=2431501&ki=A1&cc=EP

 

[Harold_V]

Okay, as far as I understand, electrotyping has been performed with cyanide electrolytes, obviously equal to nowadays silver plating in the industry - as far as I understood here on the forum.

I will not ask why, since obviously every common practice in this field has some good reasons. I assume this means, it can't be done with AgNO₃ as the electrolyte, - please correct me! If so, this little project is down.

Have you experienced the operation of a silver parting cell? If you have, you'll understand why one does not use silver nitrate as the electrolyte for plating silver.

Harold

 

[solar_plasma]

Have you experienced the operation of a silver parting cell? If you have, you'll understand why one does not use silver nitrate as the electrolyte for plating silver.

Harold

I didn't come so far yet. It is my next lesson in silver refining. But I saw the pictures and I understand.

I just experienced that copper parting in CuSO4 can form solid plates with a shining surface when taken off the stainless kathode, though it seemed to be somewhat brittle too. SoI hoped this could be done with the right additives with silver too.

Thank you, Harold!

 

[Harold_V]

Some electrolytes don't allow for a uniform deposition. Gold cyanide doesn't go on all that well, either. Pieces that are expected to be built up must be removed, buffed and repeatedly plated to build depth and retain a shiny surface. Otherwise a nodular deposit forms. And, as you noticed, silver from silver cells doesn't grow a uniform surface, either.

Of interest, when parting silver, you'd find that if you make your electrolyte without the use of any copper, the initial deposit from a silver cell can be one of uniformity. The deposit is quite robust and comes off only with a little effort, but as the copper content begins to rise in the electrolyte, the deposit becomes much softer, and the sheet that was eager to develop no longer does. I used to harvest sheets of silver from my silver cell, but they, too, quickly started growing crystals.

I was born and raised in the Salt Lake Valley, in Utah. Nearby is one of the world's largest copper mines, Kennecott Copper. In the late 60's, when I was employed by United Precision Manufacturing, we made a large number of starter sheets for the Kennecott refinery. The sheets were made of titanium, and shaped such that the copper cathode would be stripped from the starter sheets, which were reused endlessly. I got the impression that the resulting copper was rather uniform in deposit, although I never had the opportunity to see them, so I'd best reserve comment. At any rate, it appears that one can plate copper to satisfaction, although that may rely on the proper buffers in the electrolyte. Should you learn anything about this process, might be nice to share with the readers.

Harold

 

[solar_plasma]

Should you learn anything about this process, might be nice to share with the readers.

Harold

Encouraged by your words I have searched more patents and it seems that succinimide is the most proper and safe way to go. In small amounts it is easy to synthesize from probably more common chemicals like succinic acid, though not in the amount needed. On the other side succinic acid can be used to synthesize medicine products/drugs, so maybe monitored in some countries, I don't know.

Succinimide is a very weak acid. I have no clue how this is used to make silver succinimide. The easiest and for the hobbyiest only accessable way might be to buy a commercial succinimide based silver plating solution.....a somewhat expensive joy.

 

[goldsilverpro]

I moved this again. When I saw the word electrotyping, I thought it meant something different. I now realize that it is exactly like electroforming (same general techniques; different applications), a plating technique that I have a lot of hands-on experience in.

Your choice of what plating bath(s) to use must be based on one thing and one thing only - the quality of the deposit, as defined by your application - what do you need? Everything you do in the entire plating process, from start to finish, goes towards that end. The quality of the deposit is relative to the application - what characteristics are required? For electrotyping or electroforming, the final product must be thick enough to be self-supporting after separation from the mold - say, 1/32" (.03" approx) - that is about the minimum, but that would depend on the shape and size of the object. That thickness, believe it or not, is extremely difficult to achieve. Out of the hundreds of different plating solutions commonly used in industry, there are only a dozen, or so, that are capable of producing the thickness needed to be a rigid, self supporting object.

The main problem is that internal stress exists in every plating deposit, some a little and some a lot. Most of the hard bright gold found on pins, for example, will only plate to about .000500" before it starts degrading. The hard gold is highly stressed and can start stress cracking and peeling. As far as gold goes, only certain cyanide and sulfite gold baths will plate to .030000". With silver, assuming you want success, I think the only choice you have is alkaline cyanide.

The silver succinimide baths I've read about have big problems, leaning towards the possibility that they can't be used for thick deposits - poor adhesion to the substrate; highly sensitive to contamination; much more stressed than cyanide deposits.

 

[solar_plasma]

Thank you GSP!

Very informative! I hope I get the chance to try this in this lifetime. At the moment I see no responsible possibilities for me to work with cyanides. They are not forbidden for schools, but advised not to use them at all or to have them stored. This means nothing else but that they actually are forbidden IF ANYTHING happens. And I think that is allright. Though cyanides are easily made, I would never get the idea to use them outside a professional laboratory. :roll:

My goal has been to make some simple jewelries or sculptures. But, I can go the other way round and beside casting, form by etching and electrolytical dissolving. Hearing of electroforming first time from a friend and seeing the pieces that have been produced, I thought it to be much easier than anything else.

 

[Richard NL]

https://ia700202.us.archive.org/8/items/electrotypingpra00partiala/electrotypingpra00partiala.pdf

Server not found.
New link: https://ia802306.us.archive.org/23/items/electrotypingpra00partiala/electrotypingpra00partiala.pdf

Best regard,
Richard.