Electroforming voltage question

Question for Mr Wessel - Just read ME 4579 with the electroforming article. Very interesting read. The article mentions current settings but does not seem to mention the voltage used. I do intend to do some electroforming on one of my projects so I'd like to know the voltage. As the article mentions anodes and cathodes (and having fooled around with plating a bit) I expect DC was used although the article did not specifically mention it.

Looking forward to seeing test runs of the ENV engine. Great work so far on it.

Thanks JD

Edited By Jeff Dayman on 22/03/2018 19:58:25

Edited By Jeff Dayman on 22/03/2018 19:58:35

I visited the people who supply Stephen with his materials (Gateros Plating), I've had some anodising solutions off them (dies and sealer).

For both anodising and electroplating/forming they said my ordinary car battery charger would be fine.

It has to be DC. anode is +ve.

Worth contacting them for advice on plating solutions etc. I was impressed with things they have achieved like brass plating 3D prints!

Hopefully they will be producing articles on anodising and plating for MEW in the near future. They are also developing courses aimed at model engineers.

Neil

In electroplating it's the flow of current that does the work. The voltage only needs to be high enough to produce the required flow of current. That amount of current depends on the materials, the size of the area being plated, and - within limits - how fast the plating is to be done.

Generally plating calls for a DC power supply delivering lots of amps at a few volts, perhaps less than 2V. A small amateur set-up would work with a few amps; a big industrial plater could consume thousands. In both cases the voltage will be the same - low. (This is not like motors where a 1000V motor at 1A delivers the same power as a 10V motor at 100A).

It's important not to over volt whilst plating. Too high a deposition rate will form a spongy layer poorly fixed to the item being plated. Excess voltage will also decompose and heat the electrolyte. A hot gassy electrolyte full of active ions is likely to cause multiple unwanted side-reactions, all reducing the quality of the electroplate whilst wasting power.

Years ago I looked for and failed to find a suitable and affordable power-supply for electroplating, say variable 0-3VDC at 20 amps+. That was before the internet! Can anyone recommend one now?

Dave

If using a variable voltage supply you need to include a series resistor otherwise the current will be too sensitive to changes in temperature, condition of electrodes etc., and you will have to keep adjusting it. Depending on the current you require you could perhaps use an old electric fire element or just part of it.

Russell

As already been suggested use an older type car battery charger, the one with a transformer and rectifier. They easily modified to obtain a lower voltages. Being very careful you can wind on another set of windings over the top of the existing set, make tapping at every two volts, then bring the connection onto the front of the steel box/cabinet. A simple way of adjusting the current, an ammeter would be an asset but you can use a multimeter on the DC amp range. As Dave has said to higher rate (amperage) and the deposit is spongy, a bit of trial and error is needed.I copper coated a friends carburettor so that he could have it chromed, it didn't improve the fuel consumption, but he said it looked better. John

My charger is a 6/12V one with 'high/ low' settings. To be fair it was suggested that this will be ideal for anodising, especially with proper anodising dyes as the pore size is much less critical than when using makeshift colours.

A way to manage the current is by reducing the size of the anode. It's not a linear relationship but if things go too fast, one cure is to lift part of it out of the solution.

Neil

I'm not speaking from experience, but from advice I've been given by people who clearly make it work. I won't try and summarise everything I was told as I will make mistakes, but temperature and anode size seem to be most important and lower amps can be compensated for by longer anodising BUT if you use non-standard dies low amps can lead to tiny pores and poor colouration.

That did point out that its a lot easier to match your own work by using a consistent process than to achieve a specific result like professionals do.

Neil could you please pass on my info request to Mr Wessel? I'm assuming you have his contact info since he contributed the article. I'd simply like to know what voltage he used to get his very successful copper electroforming results as seen in ME 4579, nothing more. The thread's gone way off topic from the original info request. Thanks JD

Hello Jeff. Neil drew my attention to this forum post.

What you need is a small, cheap power supply. The one I use came from www.rcpitstop.co.uk and is called Fusion 200W twin output adjustable, PS201ADJT, cost £35.95. This was the cheapest supplier I could find but the same model is offered elsewhere.

In my previous electroforming work I used a 12V battery with various resistances in series (light bulbs etc) to get the current I wanted. The current is your starting point so you must have a ,means of measuring it. I used my multimeter. Then you can use really any source of DC power and it doesn't matter what its nominal voltage is. The Fusion will show you the actual volts & amps and the volts will probably be around 1 to 3 depending on the size of the job.

I cannot emphasise enough that getting a Fusion or one like it will remove so many headaches and constant hunts around the shop for resistors and bits of wire, connectors, bad joints etc etc. I found the current remained absolutely stable despite changes of temp for hours on end. OK it's 40 quid but I don't think you would regret it as it removes a kind of mental barrier to all sorts of plating you might want to do in the future. Just plug in and go!

You must calculate your current density in advance using the area of the cathode. Industry usually quotes in A/dm (amps per decimetre) but I prefer A/ sq inch. Keep this lower than advised by industry sources, especially if using copper scrap as the anode, to ensure a fine grain smooth deposit. Any sign of nodules means that current should be reduced.

Another tip is to stir the electrolyte and avoid air bubblling which creates a fine mist all over the place, corrodes your connectors and depletes the solution.

BTW Gateros Plating is a good company, very approachable and friendly. They are writing a book about plating and about to run classes as Neil said. Also they realise that their website and instructions sent out with kits are a bit sparse on info, so are taking steps to improve all this.

Good luck with your project

Stephen Wessel

I sympathise with Jeff who asked about electro-forming only to learn about anodising! Anodising and electro-forming are different processes. What's best for one isn't good for the other.

In anodising an electric current is used to increase the thickness of the surface oxide layer. It is not a metal plating process at all. As it's often wanted to colour the anodised surface it's good to make the oxide layer porous to take a dye. It helps to encourage the porous layer by applying more volts. Compared with electroplating the bad effect of using too many volts is less obvious. Anodising is altogether more tolerant.

In electroplating an electric current is used to deposit metal on to a conductive surface. The aim is to deposit a solid layer of pure metal, uncontaminated by oxides, with no pores at all. To do this well requires careful control of the current flowing. Unwanted side-effects are minimised by carefully increasing the voltage from zero until the required current is flowing. Probably between 1.2V and 5V. I expect this is the answer Jeff will get from Mr Wessel.

In professional electroplating equally careful attention is paid to the electrolyte. Potassium Cyanide is good if you can get it! It's difficult for amateurs to electroplate as well as a professional because they have all the advantages. Equipment necessary for cleaning, plating tanks with proper electrics, difficult to get chemicals, and a good understanding of electrochemical best-practice. I'm impressed by Mr Wessel's results.

Dave

Edit: Typical - I press send only to find that Stephen got in first.  I hope his answer doesn't make mine look too foolish!

Edited By SillyOldDuffer on 24/03/2018 11:08:57

The products I ordered all came with about six pages of detailed manufacturers datasheet, so it looks like they have.

Neil

I totally agree with Stephen and S.O.D. It's a matter of basic electrochemistry. The rate of deposition is directly proportional to the current flow. In fact the Ampere was originally defined according to the rate of deposition of silver on the cathode in a silver nitrate bath.

Controlling the voltage only indirectly controls the current.  It is non linear and sensitive to things like temperature.

You need to control the current and thus the deposition rate to get the best surface finish and adhesion.

Russell.

Edited By Russell Eberhardt on 24/03/2018 11:35:48

duplicate  post in error, sorry

Edited By Jeff Dayman on 24/03/2018 12:05:04

A useful book I have on amateur electro-plating is "Electro-Plating" ,fully illustrated, one of the little "Amateur Mechanic & Work" handbooks, its probably pre WW2, but not too far back, it covers chrome plate.

Ian S C