[quentief]

Good Morning everyone

I create this topic because I have been told about a metal forming process : the electroforming, a very interesting process which apparently make able to form metal without the need to melt it.

I have tried this with iron (I have used an electrolyte of iron sulfate) and it seems to work but not like I was expecting. As you can see on my pictures, this process formed some kinds of metalic branches (I assume this is called dentrite) and, despite the beauty of this chemical phenomenom, this is not suitable to make metal objects.

Have you ever expermimented this process ? Maybe you could give me some advices to improve my machine, especially to avoid these dentrites.

Oh and I'm sorry for my english, I am a poor french which is trying to improve his english as better as he can Actually I have some difficulties to choose between your preterit and you present perfect 

[quentief]

I am really sorry, I forgot to send you the photo of my work. Here is :

[pcm81]

Electroplating and electroforming (which is basically electroplating on steroids) are driven by current. The current peaks at sharp points, hence you have accelerated growth at those points. In turn, this accelerated growth at sharp points created "growth" effect. Polish the wire with fine sand paper and try again. Current density will have an effect as well. Too much current = porous "burnt" deposit.

Also, experiment with zinc. It is much easier to get started with. Much more forgiving process.
Depending on what you are plating on what, you may need to use pickling solution prior to plating.
Not every metal can be plated onto every metal. Research topic of Reduction potential, galvanic reaction, "Nobility" of metals. The metal you are plating must take electrons from the metal you are plating onto to get reduced to metallic state from the ion on acid.

[Enthalpy]

Nickel is commonly used to create items by electroforming. Hobbyists deposit it on lead, later molten away to make thin hollow parts for model boats. Possibly the best source of information for home process.

On the picture, the layer may not be iron, but some oxide or salt. Iron isn't the easiest metal to deposit, because it rusts in water.

[quentief]

Thank you for your answer. I will try what you adviced to me .
In my experiment, I used a power supply from a laptop (a voltage of about 19 volts). I suppose, the voltage needs to be reduced.
I would like to know more about the current density, what does define a good voltage and a good intensity ? I suppose that depends of the surface of the object and of course the metal I want to use, but how can can I calculate these parameters ?

Thank you in advance for your help 🙂

[quentief]

I am sorry Enthalpy, I didn't see your message . Concerning the metal, well, at the beginning it was metallic iron.
The problem is iron has quickly turned into rust when I let it dry under the sun. But I think I can avoid this problem by neutralising the acid electrolytic when the electroforming process is done. I think this is already done in copper electroforming, to avoid the oxidation of the copper at the end of the process.

[Enthalpy]

19V is too much. Very few volts would be better. ATX power supplies deliver +3.3V and +5V with a huge available current and used ones cost nearly nothing. You must short-circuit two pins and the mainboard connector to start them.

The current density in A/dm² defines the deposition conditions, as well as the bath temperature and concentration. A stronger density makes a rough layer more probable, a cold bath too. More current shall not result from a high voltage, since unwanted reactions appear then.

I didn't find any more the address of the NiDI's document, so it's appended here.

[quentief]

Okay so according to you Enthalpy, the lower the current is and the hotter the electrolyte is, the more uniform the metal deposition will be. So you advice to me to heat up the electrolyte and to limit the current to have better results. Do you ?

I am sorry if you meant the contrary, I have some difficults to understand what is a roughly surface, I am not sure about the French translation. Anyway, could you validate or invalidate what I assumed ?

[Enthalpy]

Yes, that's my understanding too. Beware electrochemistry is tricky.

I'd keep away from iron. Nickel is the standard choice for easy electroforming, and most industrial electroformed parts are of nickel.