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Copper electroforming problems

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A discussion started in 1995 but continuing through 2018.

Electroforming copper onto tin mandrel

December 2, 2013

Q. Hello, I'm a spanish artist. Sorry if my english is not very good. I'm trying to electroform a copper layer on a surface of tin. How can I do to passivate the tin? Nitric acid, chromic acid? For electroform a thick layer of copper on the surface of tin, Do I need an alkaline bath or an acidic bath? Has anyone tried the cyanide-free alkaline baths sold by hobby plating suppliers? Are there other options? Many thanks.

antonio sanchez
- spain

December 18, 2013

A. The most common copper electroforming electrolyte is an acid based one, using 200-250 g/l copper sulphate with 50-75 g/l sulphuric acid; temperature about 25-30 °C and current density 2-10 A/dm2. Anodes are phosphorus deoxygenated and agitation is air or mechanical

Trevor Crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK

Can electroform small wax objects but not big ones

July 12, 2014

Q. Hello everyone--

I am a sculpture artist who has built his own electroforming chamber up from a beaker, to a gallon, to five gallons, and now I'm in the ten gallon range. I use lab-grade copper sulfate, brighteners, and car battery acid as sulfuric acid. On a good day, I can get bright penny out of my chambers.

I've been having some pretty tricky problems of late, however, and I wonder whether they are due to the fact that I am a do-it-yourself outfit, or whether I'm missing something fundamental. The biggest is that my larger items--an object as big as a head/bust, and one of a hand/forearm--refuse to plate. With the one, I'm using Rio Grande's copper conductive paint, and with the other, I'm using a graphite paint--all to no effect.

Now, I have a technique where I sculpt a wax form, lay copper kitchen scrub pads over the object, and then electroform it from there--the result is that the threads turn into wires, then I evacuate the wax. I've had success putting the graphite paint in between the spaces between the threads, and they accumulate copper very nicely. Also have seen successful electroforming laying down paper letters on to a copper plate, varnishing the letters, and then applying conductive paint.

In a nutshell, I don't seem to have a problem when there is actual metal helping out--but failure after failure when I'm just using conductive paint over a large wax form.

Help! And very much thanks in advance!

Eric Caldwell
Caldwell Sculpture and Design - Charlottesville, Virginia, USA

July 2014

A. Hi Eric. I'm only half understanding your clever use of copper scrub pads, which is something I've never heard of. But I think I can guess what is wrong with your graphite-only or copper paint-only approach to large objects, and that is that the metallization can only carry a very low current without burning. When you are plating a small object the thinness and limited conductance of the graphite/paint isn't a severe limitation, but on larger objects it is. I think you need to find a way, whether it is with copper scrub pads or some other way, to bring electrical contact to many points so you don't have more current flowing through the metallization layer than it can sustain. Alternately, it may be possible to electroplate at a very low current density for a little while until you have a good conductive "shell" that can carry many times more current than the graphite "shell" … then you can up the current density to your usual values.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

August 11, 2014

A. Good, usable and download free book on that subject is Die Galvanoplastik by russian german Moritz Herman von Jacobi (inventor of electroforming). Hope it helps and good luck!


Very good old book in English (same subject):
Goran Budija
- Zagreb,Croatia

August 5, 2014

Q. Hi, I am trying to electroform some jewelry. I have some electroplating solution. Will it work as is to electroform? One person said yes, another said no. I can't find any information on the chemical difference. I bought paint from Dalmar and no plating stuck to it, but did stick to any metal I used in the pieces. I am getting very frustrated.
Please help!

Sylvia Farrell
- Cornville, Arkansas U.S.A.

August 2014

A. Hi Sylvia. Electroplating/electroforming isn't necessarily easy. For some of the regular readers and visitors to this forum, electroplating has been their career for 50 years, yet they are still learning. So patience is a requirement.

Semantics: the difference in "electroplating" vs. "electroforming" is pretty simple: if you have an object and you put a thin coating of a metal on it (like the chrome plating on a truck bumper or the rhodium plating on a white gold ring), we call that 'electroplating'. But if the plating actually becomes the object, not just a coating on it (for example, hollow gold earrings which are made by plating gold onto wax which is later melted away), then we call it electroforming … simply because we've 'formed' an object.

When we electroplate onto a leaf or a flower, most people will call it 'electroforming', but it's a bit ambiguous -- is it a flower that has been plated, or was the flower just a form and the metal is the object of interest?

Yes, in general you can use electroplating solutions to do electroforming. But in every endeavor, tweaks are possible, and customizing to a given purpose can improve performance. A plating solution optimized for plating bright nickel will probably not be great for electroforming heavy layers because the metal will be very highly stressed. So those who say you should use 'electroforming' solutions are not exactly wrong either :-)

I don't know what kind of metallizing paint you used and what kind of plating solution you are using, and we have no other data, so it's hard to say why the plating isn't sticking to the paint. There could be a lot of reasons. But I'd suggest you practice plating on metal and become reasonably competent at it before you introduce plating onto conductive paint as yet another variable to tame. Best of luck.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

August 28, 2014

Q. Thanks for responding. I am using Krohn's copper electroplating solution, and Delmar's copper conductive paint. The man at Delmar was very helpful, and said the electroplating solution should work. After many frustrating trials, I am now getting good results. I seem to be getting better results as the paint thickens; also, most of my problem was not getting good connections to all parts where the paint was. I am taking more care now.
I still wonder about my question about the difference between electroplating and electroforming copper solutions. Every recipe I find for either, seems to be the same. They never point out a difference in the chemicals. Maybe the ratios are different.
Thanks again,

Sylvia Farrell [returning]
- Cornville, Arizona U.S.A.

August 2014

A. Hi again. Glad to hear of your improving success.

I tried to answer your question about electroplating vs. electroforming, but I'll try again:
Electroplating is usually (although not always) very thin. Gold or rhodium plating, for example, is usually well under a micron thick (40 millionths of an inch). But an electroform, since it is an actual usable object, is thousands of times thicker. The problems that may arise at this thickness include too much internal stress in the plating, which will causes the electroformed object to curl up. This is especially a problem in nickel electroforming, for which much different solutions are used than in bright nickel electroplating. But copper is a soft and low stress metal, and some copper plating solutions seem to be fine for both applications.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

August 29, 2014

thumbs up signThanks Ted, Believe me, I thoroughly understand the difference between electroplating and electroforming. My question was "what is the difference in the chemical make up of copper electroplating solution and copper electroforming solution that vendors sometimes insist you have to buy to copper electroform?" Is it just the same solution with two names?
If you want to make your own solutions, the same recipe for either are given, so what are these vendors trying to sell us to buy? In DIY tutorials, I keep seeing the recipes for copper electroplating when they are showing us how to copper electroform.
I am not having any trouble now electroforming with the copper electroplating solution, as the man at Delmar said it should work fine and it does.
Still curious!

Sylvia Farrell [returning]
- Cornville, Arizona

November 2014

A. Hi again. A given copper sulphate bath can be used for both copper plating and electroforming, so those who say one bath are right rather than wrong. But anything can be optimized.

Canned coffee sellers offer this grind for Mr. Coffee machines, another for electric percolators, another for expresso, another for old fashioned percolators -- is it actually imperative to pick the perfect grind? Is copper plating solution the one thing that cannot be optimized for plating vs. electroforming? Certainly it is possible to put a brightener into a copper plating bath that is designed to make the plating hard and bright, but which will not be a good idea in an electroforming bath.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

November 15, 2014

Q. Hi -

I have been electroforming both organics and onto cast metals for some time. I am now having a problem with the solution crystallizing onto my copper anode. I make my own solution with copper sulfate pentahydrate, distilled water, and acid. I have also found that the solution is evaporating very quickly these days. Any thoughts on either problem?

Chris Carpentino
- Savannah, Georgia USA

November 2014

A. Hi. Copper concentration tends to grow in acid copper plating, especially if you are plating at low current density, which is usually the case when electroforming. Are your anodes phosphorized copper? If not, that should help. Please see letter 848 for a good discussion of copper anodes. For now, you may have to dilute the solution to get the copper concentration down.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

November 11, 2015

Q. I am a Costume Designer/Artist/Professor and I have been playing with electroforming a variety of materials for use in my designs. My boyfriend has been helping and last night he left the copper anode in the solution with nothing in it and no current on. He doesn't believe me that this is a BAD IDEA. Could you explain exactly why he should not do this? Aside from wasting copper, does is do any harm to the solution? Is there a way to clean it? Or do I even need to clean it?

Nola Yergen
Artist - Phoenix, Arizona, USA

November 2015

A. Hi Nola. This is not generally considered harmful. Large plating shops almost always leave the anodes in their tanks all the time.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

January 16, 2016

Q. I'm a recent fine arts sculpture grad and am looking to continue my path with sculpture by starting a small hand made jewellery business. I just wanted to check on the rectifier voltage and amperage before I purchase one, as well as the cathode.

For the rectifier I'm looking at either a 0-24 DVC and 15 Amp. However, since the rectifier is not digital would this be sufficient for copper electroforming? Or should I go with a lower amp that is digital which would be 0-30v 5amp? For my cathode I would be electroforming brass rings which I have read do not require a nickel plate as copper adheres well to brass. The brass ring will have a gem epoxied to the top, the epoxy will be painted with a copper conductive paint. I'd like a somewhat thick layer of copper to build around the ring and gem. Could you please let me know if I'm on the right track with the power of the rectifier and material of the cathode?

Many, many thanks,

Rachel rose
- Peabody, Massachusetts USA

March 2016

A. Hi Rachel. The rectifiers you mention have far, far more voltage than you need. You'll almost surely never use even 6 Volts. And 5 Amps should be more than enough for any ring-sized object; Henry suggests 1/10 Amp per square inch of surface area and I'm confident that he's right and you should not exceed this.

I think you'll be able to plate onto brass substrates with reasonable adhesion from copper sulphate.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

Copper electroforms were good at first but now they are grainy

February 10, 2016

Q. Hello!

Thanks for providing such an informative thread. I have had a recurring problem that I usually solve by buying more copper electroforming solution, but I have to wonder if there is a better way to resolve my issue. With my current bottle of electroforming solution I have produced roughly about 100 pieces of jewelry (none substantial in size) that have all turned out with such a great finish. Now they are coming out with the texture of sandpaper, if monitored frequently, and large forms or branches, if monitored less frequently. I am keeping my amperage low and I'm using Rio Grande's electroforming solution. Does it simply need brightener or should I play with different variables? I know temperature was mentioned as a variable in another Q&A, what is an acceptable temperature to electroform copper and how would you recommend regulating it? I also read that it's helpful to agitate the bath, could that be a possible solution?

Thanks so much for sharing your wisdom!

Caitlin Paige
- Austin, Texas US

February 12, 2016

A. Hello Caitlin, there are a few causes for rough plating. Brighteners are a grain refiner for your deposit. After plating so many pieces it should be added by a certain amount of ampere hours. Your tech data sheet for the solution will give you that info. I find that a Cu sulfate bath plates/electro-forms best at 70-75 °F. If the temp rises, a small chiller or an easy method of cooling (your discretion). Another cause is organic contamination. I don't know the volume of your solution so maybe a small filter with a carbon pack for 2 hours maximum. The other common cause is particulate matter in the Cu solution. Filtering through a 5-10 micron filter will solve that. Depending on your anode setup if using small Cu anodes they should be bagged with polypro or Dynel bags. Do not use any bags with a cotton content. You have some measures available to you to keep the solution longer. Good Luck!

Mark Baker
Process Engineering - Phoenix, Arizona USA:

March 5, 2016

Q. I have been getting into electroforming, but have run into a few snags along the way.I have multiple questions.

1. I have a magnetic stirrer with heat. Is it better to electroform with warm solution or cold? (I get a better current when its warm)

Copper Sulphate 10 pounds

2. What should the current and voltage be if I'm doing a bunch of small rings at once? It seems to more all over the place. Sometimes the current will just stop working all together in the middle of a plate. Any idea why?

3. I heard Root Kill is basically the same things as the solution you get at Rio grande. It this true and is it safe to use. It's 99.9 percent copper sulfate.

4. I've been getting some uneven pieces and am not sure why. I use gloves to touch the pieces to ensure there is no oil or dirt on them while I'm painting them, but seem to still have some places that won't plate. Any cleaning solutions I could try before I paint?

5. Do you know how to make your own conductive paint or glue. I can't find one that I like.

6. How often should I be changing the copper solution and anode?

Thank you for any info you might have :)

Megan Carli
- Brooklyn, New York

Foam buildup from aerating my copper plating solution?

March 13, 2016

Q. Guten tag from lovely Rostock, Germany! I am an electrician by trade but also an avid fan of making copper jewelry. I was really excited to try out this crazy "electro forming" all the kids are talking about, and last week acquired the various bits and things I needed to get started. In my haste and excitement my first attempt was a total disaster, upon which I found and read through this forum. Thank you so so SOOOO much for all the great questions and answers! I actually literally found solutions to all my issues here! What a great resource!

I DO however have one question … I bought a small aquarium pump, but found that if I leave it on continuously, a layer of foam builds up at the top of my solution which left unchecked would flow over the top of my beaker. Do you have any suggestions as to how I may remedy this?

Also, since I am already asking questions, what is the lifespan generally speaking of the solution itself? Like, specifically if I am doing small pendants approximately 2 square inches of surface are for a time of 6 to 8 hours each at 0.2 amps … roughly how many times can I repeat this process before I require new solution?

Thank you again for all of your great help!

Ian Mccallum
hobbyist - Rostock, Mecklenburg Vorpommern, Germany

"The Canning Handbook of Surface Finishing Technology"

from Abe Books

March 2016

A. Hello Ian. There are wetting agents made for air agitated plating baths to prevent this foaming; the supplier of your copper plating bath should know about them. Electroplating baths are "equilibrium processes" which are designed to -- if all goes well -- run forever; in industrial applications, copper plating baths are filtered, and various purification steps are taken as needed, and the plating bath is almost never dumped and re-made.

If your library has a copy of The Canning Handbook =>
it has a good chapter on copper plating, and another good one on electroforming.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

March 8, 2016

Q. Hello I just bought a rectifier to start electroforming/electroplating copper onto geode stones. I know of the materials I need, but I do not know what is the difference between bright copper electroforming solution vs. Bright copper electroforming with Acid. What is the purpose of the acid? Do I need it? Thank you.

julie afzali
- brooklyn new york USA

March 2016

A. Hi Julie. I suspect that nobody except the particular vendor who is offering that solution can tell you what it means. Both solutions are probably "acid copper sulphate" based.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

March 21, 2016

Q. I recently moved. When I did, I bottled all of my electroforming solutions in their original bottles and boxes, packed them away and had hopes of reusing the solution once I got my studio back up and running.

I am using a small 1 gallon fish tank to electroform which uses a fish filter/air pump for agitation. I am using silver conductive paint and a large piece of copper for an anode. In the past (after the first hour) I could see the plating happening and could just let it do its thing. My piece has been in the bath for over 12 hrs now and has barely any plating, and that is salmon in color. It seems to be happening a lot slower than in the past. Although I switched the containers I was using, they are the same size and material so that doesn't seem like it should create any problems. Do you have any idea what could be the issue? I guess I'm going to let it keep going but its highly frustrating. Do I need to add acid to the mix? Please help!

Alexandra Camacho
Art/jewelry - los angeles, California, US

March 21, 2016

A. Alexandra: It sounds like you are getting little if any current flow. Check that all electrical connections are clean and tight. It would be best if you had an ampere meter, but even a simple DC volt meter will help. You can pick one up at a big-box hardware store that will read low voltages. Depending on your setup, you'll probably need 2 or 3 volts. Or if you can measure amps, maybe 4-8 amps per square foot of surface being plated.

Are you certain you don't have the connections reversed?

(+) to the anode (-) to the part.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina

March 21, 2016

Q. Hi!

Thanks for responding. I use a digital rectifier and I always have used it on the lowest setting and has worked fine for 1-3 pieces up until the move. I turned it up to .85 and the the other setting changes along with it to compensate I guess? Do I still need to check the amps and volts if it's showing current on my rectifier?

Alexandra camacho [returning]
- Los Angeles, California

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