Electroforming of Silver

A. Hi, Robert. Many of the world's electroforming authorities gathered in Las Vegas for 3 days in 1996 for an AESF & NiDI Electroforming Course & Symposium. Contact AESF to see if proceedings are still available.

Many texts serving the industry at least briefly cover silver and electroforming, but I know of no text focusing specifically on silver electroforming. If you can't find the proceedings of that seminar, I think you'll need to do a literature search to pick up individual citations on the subject. Good luck.

A. "Electroforming -- A comprehensive survey of theory, practice and commercial applications" by Peter Spiro B.Sc.(Eng.), A.C.G.I., A.M.I.Mech.E., A.M.B.I.M. Publisher: Robert Draper Ltd Teddington 1968 ⇨

A. I suggest you use a disposable mandrel because the wall thickness is so small there will be little inherent strength in the tube. If you use a permanent mandrel, you may find it difficult to remove the electroform from the mandrel. You can use aluminium and dissolve it out in alkali. I would use a cyanide bath to deposit the silver and rotate the mandrel.

A. Hi Azizur. Aluminum mandrels should probably best be zincated, then cyanide copper struck, then silver struck, then silver plated.

As for composition, as Alan Blair says in the Metal Finishing Guidebook, they have been essentially unchanged for 180 years now. If you have no plating textbooks on hand, download the Guidebook (but don't work with cyanide without hands-on training in it).

Luck & Regards,

A. Practically all silver plating is done from a cyanide solution which is highly toxic.
As well as the obvious hazards, there is a problem in disposing of waste.
There is also considerable cost in purchasing silver anodes and plating salts.
If you do not have experience in handling toxic chemicals and electroplating technology, electroforming is best left to properly equipped professional shops.
Why not discuss your project with a local plating company. If you produce the masters, they can do the plating.

A. Hi, Gregory. Silver can be plated at least thick enough to be "self standing". For example, jewelry can be manufactured by starting with a wax form, metallizing it, silver plating it, and then melting the wax away. When the plating is thick enough to be self standing like this, and the plating becomes the object rather than a coating on an object, it is sometimes called "silver electroforming". If you search for that term I think you will find the examples you seek. Good luck.

Regards,

A. Hi,

I recall seeing a copper electroform that had run amok and looked rather like a coconut. I don't think there is any actual limitation on size.

Regards,

A. Gregory, You can electrodeposit as much silver as you like if you start doing electroforming. As Ted says, this creates a free standing article, but the only limitation is the length of time you want to spend making it. I have seen electroforms that range in thickness from a few tens of microns up to and inch or so. There are numerous textbooks on the subject of electroforming, so it is worth consulting them for further advice.

A. You can try next solution: 200 gms potassium ferrocyanide ⇦this on eBay or Amazon [affil links] /20 gms potassium carbonate/40 gms silver chloride/1 lit water/SS anodes. Pyrophosphate based bath can be used too.
I think that there is at least one proprietary bath (SILVERON GT-101 Bright Silver). Hope it helps and good luck!

"The Dose
Makes the poison"
by Frank & Ottoboni

on AbeBooks

or eBay or

Amazon

(affil links)

A. potassium ferrocyanide ⇦this on eBay or Amazon [affil links] based plating solutions are oldest cyanide-free silver and gold plating processes (1843 !!)
Potassium ferrocyanide is nontoxic, and is not decomposed to cyanide in the body. Lethal dose for rats is 6400 mg/kg - it is harmless if compared with potassium cyanide (10 mg/kg for rats). It and the related sodium salt are widely used as anti-caking agents for both road salt and table salt (FDA approved!) Hope it helps and good luck!.

A. Amateur hobbyist. Here is my go-to silver plating recipe. Mixing isn't as straight forward as throwing everything together, so pay attention.

Dissolve 5 g SILVER NITRATE into 250 ml distilled water. Dissolve 4 g KOH (POTASSIUM HYDROXIDE) into 100 ml water in separate container.
Pour KOH solution into silver solution and stir, it will turn black.
Slowly add 8 g PYRROLIDINE (SUCCINIMIDE) while stirring until clear.
Add 4 g more pyrrolidine, 4.5 g KNO3 (POTASSIUM NITRATE), and 2.1 g more KOH. Stir.
Add 1.5 g AMMONIUM THIOsulphate (or 3 ml Kodak Rapid Fixer part A) as the brightener.
Half a drop of DAWN dishwashing detergent.
Add 425 ml more water.

Use very low voltage, start at 0.1 Volt, over-voltage will make dull finish. Copper will auto plate with no current. Use pure silver bar on positive, work on negative.

Hope that helps. Works for me.

A. Hi Monica
David's posting was from 2-1/2 years ago and we should probably leave him rest after his careful efforts toward clarity (no auto-completes for David) ... but we'll e-mail him and see if we can reach him and he responds :-)

Luck & Regards,

Usually available on eBay;

sometimes on
AbeBooks or Amazon

(affil links)
free pdf is currently available from academia.edu

A. Hi Suz. Virtually all silver plating is done from a toxic cyanide based solution as it has been for 150+ years, and cyanide has no place in a home studio. You might investigate the availability of a non-cyanide plating solution from EPI / Electrochemical Products Inc. [a finishing.com supporting advertiser], or a hobby plating supplier, or further investigate Goran Budija's discussion of non-toxic ferrocyanides.

As for how to do it, the Metal Finishing Guidebook has a very good chapter on silver plating, including surprisingly detailed info on non-cyanide plating processes. After that you can search the site for lots of Q&A's about silver plating. Good luck!

Luck & Regards,

A. Hi John. We appended your inquiry to a thread where you will learn that silver is electroformed to thicknesses much greater than that ... the thickness should be no problem at all.

As for technique, it depends on what those small objects are made of. It's generally advisable but probably not necessary to do a layer of nickel plating first. But silver is a very noble metal, very prone to (non-adherent) 'immersion deposits'. At the least, the parts should be electrically hot (connected as a cathode) for hot entry. Even better, the parts should get a silver strike first -- a deposit from a silver plating bath which is dilute, higher in cyanide, or otherwise very reluctant to deposit silver. This way it will not 'immersion deposit'; and once you have that thin silver strike you needn't worry about 'nobility' because you're plating silver on silver. The previously mentioned Metal Finishing Guidebook tells all :-)

Luck & Regards,