Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: Pumblechook on 06/09/2013 20:15:24
-
Copper. Zinc, Silver, God, Chrome etc...elements.. Plating seems straightforward but brass is an alloy??
-
God is an element? [;D]
To answer your more serious question, though, brass plating is simply not possible. If you used a brass anode, you might achieve either copper plating or zinc plating (depending on other conditions) but not both. Even hot dipping is problematic because of the volatility of zinc: A "safe" brass melt would not be hot enough to achieve good surface adhesion to a metal
-
You can plate an object sequentially in copper and zinc and then heat the object over an open flame or furnace to produce a brass finish--but make sure object can withstand the heat! I don't know the quality of finish produced by this method, but it makes for a very nice classroom demonstration.
-
Actually, it is possible, but difficult.
You need to ensure that the amount of copper in the solution is so small that the potential needed to plate it out is high enough to plate out zinc at the same time.
That's not really practical, so they add a complexing agent to hold back the copper.
https://www.google.com/patents/US4104138?dq=%22brass+plating%22%22&hl=en&sa=X&ei=hrMwUv-bJ46ShQez7YDIDQ&ved=0CFMQ6AEwBA
-
You can plate an object sequentially in copper and zinc and then heat the object over an open flame or furnace to produce a brass finish--but make sure object can withstand the heat! I don't know the quality of finish produced by this method, but it makes for a very nice classroom demonstration.
Here is a nice demo that I bumped into today.
Copper pennies into silver and gold (http://science.wonderhowto.com/how-to/turn-pennies-into-silver-and-gold-coins-with-zinc-367856/)
The description is cut off, but the video is good.
-
Thanks CliffordK! That's precisely the demo I was thinking of!
-
Hi
Well the chap I buy my plating equipment from seems to think it is possible and not difficult.
[Mod: Commercial link removed]
All kits and equipment I have purchased from these guys has done exactly what it said on the tin, I have spoken to the owner several times and if he says it works and works well then I would tend to believe him.
The anodes are brass and the finish is reported to be a brass colour not a copper one or a zinc one so I would suggest that both metals are indeed being deposited. I have not yet brass plated but I am toying with getting the brass kit at some stage, I already have others.
Not being a chemist I decided to back it up by a Google search and yes there are professional plating shops out there offering to do brass plating so I would conclude that it is indeed possible and apparently not difficult.
Jon
-
Damocles wrote: "To answer your more serious question, though, brass plating is simply not possible."
Since my last posting I have successfully plated with brass myself, the set up I used was very crude with sodium hydroxide as the electrolyte and a single brass anode, the plate was not pretty but it was well adhered.
Since my last posting I have read many research papers on alloy plating - plating of many alloys is possible and is done routinely on an industrial basis.
The one difficulty is achieving the desired ratio of each metal since they will often have dissimilar electropotentials and one metal may deposit preferentially. Electrolytes are designed to solve these problems with various additives and formulations.
The certainty and confidence of the negative assertion offered above does highlight the issue of information offered as fact on the internet which is not properly supported. Opinion, hunch or conjecture does not substitute for fact so please dont offer it unless it is declared as opinion or hunch.
Try searching "brass plating" on google (uk) - On the first page I found various commerical and 'diy kit' offerings as well as this thread, images of brass plated items and on subsequent pages several patents relating to cyanide based methods for brass plating.
Historically professional brass plating has involved cyanide salts and therefore not ideal for diy plating, however alternatives do exist for the amateur.
Recent developments in the plating world include ionic liquids replacing water as the solvent in the electrolyte and this has opened possibilities not available with water based systems.