Electroplating with common household ingredients

[Brian-M]

I'm trying to see if I can successfully electroplate stuff using only common household items. I was wondering if anyone can give me any advice or suggestions?

So far, instead of a battery I've started with a variable-voltage bench-top power supply I had lying around, so I can better control the current while I'm trying to get it working.

I'm currently using a solution of water, salt, vinegar, citric acid and sugar, all mixed into a large glass storage container, with some copper wire for the anode.

It seems to be sort-of working. The water has turned a beautiful vivid shade of blue from all the copper dissolved in it and the cathode (usually a teaspoon, key or nail) is being coated with a brown layer of what I assume is copper.

The problem is, the brown (copper?) coating looks darker than I think it should be, and wipes right off. What a I doing wrong?

(Also, is a little bubbling OK, or should I keep the current down far enough that nothing visibly happens?)

 

[Andrew Wiggin]

I'm trying to see if I can successfully electroplate stuff using only common household items. I was wondering if anyone can give me any advice or suggestions?

So far, instead of a battery I've started with a variable-voltage bench-top power supply I had lying around, so I can better control the current while I'm trying to get it working.

I'm currently using a solution of water, salt, vinegar, citric acid and sugar, all mixed into a large glass storage container, with some copper wire for the anode.

It seems to be sort-of working. The water has turned a beautiful vivid shade of blue from all the copper dissolved in it and the cathode (usually a teaspoon, key or nail) is being coated with a brown layer of what I assume is copper.

The problem is, the brown (copper?) coating looks darker than I think it should be, and wipes right off. What a I doing wrong?

(Also, is a little bubbling OK, or should I keep the current down far enough that nothing visibly happens?)

A few comments.

Using an acid or a salt to make the solution conductive is sound science. The sugar isn't an acid or a salt though, so it's not going to participate except to gum up the works. Is this something you're just figuring out as you go along, or was there a reason you added the sugar?

Why the complicated mixture of salt and acids? That's going to make lots of ion species in your plating bath, but there's really no benefit to that. Did you try these individually before mixing them, or was this a 'dump it all together' experiment? You should be able to plate with copper chloride, copper acetate, or copper citrate, as they all should be soluble, but without testing them individually, there's no reason to think they'll work better or worse when combined than alone. These aren't the ion species usually used to plate copper though. You could probably find info on the interwebs about what goes into a plating bath, and what counts as household chemical depends for the most part on your ingenuity and label reading skills.

I've had some success copper plating with copper sulfate and sulfuric acid. I'm not sure if that stretches your definition of household chemicals, but I did get the copper sulfate as 'root killer' in a grocery store, and the sulfuric acid at an automotive place. You could also use sodium bisulfate, sold as tile and toilet bowl cleaner.

Getting a smooth deposit of copper is a matter of finding the right current density, and also of having the item to be plated really really clean. Your mixture of stuff isn't really helping with the clean part. I really do want to emphasize that you need a clean and pure plating bath. Distilled water, pure chemicals, and nothing but pure copper as your electrode. You'll need to get the piece to be plated as clean as you can. Scrub it with detergent. Rinse it with distilled water. Even then, it's probabally not clean enough. I've had success reversing the polarity in order to blow the surface layer of the piece to be plated clean.

As far as current density, if you've made a clean plating bath, cleaned your workpiece, tried reversing the current to electropolish the workpiece, and you're still getting powdery deposits, then you're running too much current density. Reduce your bath conductivity, reduce your electrode area, or turn down your power.

Hope that helps a bit.

A

 

[Brian-M]

Thanks for the suggestions. As for the mixed mixture, it's the result of a making-things-up-as-I-go approach.

I started with just a large amount of table salt and tap water. While that was bubbling away, turning green and giving off chlorine I found a web-site about electroplating with the following info:

A recipe suggested by Tom Pullizzi, and found to work is:

Fill the container about half way with vinegar (vinegar is mild acetic acid). Put the zinc anode into vinegar and let it sit for several hours, allowing some of the zinc to dissolve.

Add 100 g/l of Epsom Salts (this salt helps make the solution conductive)
and 120 g/l of table sugar (this is called a "brightener")

Connect one flashlight battery (1-1/2 volts) to the penny and the zinc anode, and place them into the solution. Don't let them touch each other. With luck, within a few minutes you'll begin to get a bright silvery coating. Ted Mooney didn't have quite that much luck when he tried it, but did find that a reapplication of the toothbrush and toothpaste quickly polished the thin greyish coating he got to a fairly bright shine.

I assumed then that an acid of some kind was important, so I mixed in some vinegar and the solution turned blue very quickly afterward. After trying to find some info on brightening agents, I decided what the hell and added some dissolved sugar in case that helped any.

Later I went down to the shops and got some citric acid so I could make the mixture more acidic if I wanted without diluting it with vinegar, and some Epsom salts (magnesium sulfate) so I wouldn't have to use sodium-chloride next time I tried it.

When I try this again tomorrow, I'm going to use less ingredients and keep a record of exactly how much of what goes into it. I might get a bunch of spoons and stuff from a second-hand store to practice on too.

Here's a picture of my current setup...

 

[Andrew Wiggin]

I googled the info you provided, and it looks like the epsom salts and vinegar formula is specific to plating zinc. If you're looking at the source I think you are, there are directions for plating copper using acetic acid electrolyte about a page down. It calls for vinegar with a 'pinch of salt and sugar', and warns that the conductivity is low and the solution won't hold a lot of copper, so it plates slowly. The low conductivity is just because acetic acid is a weak acid and doesn't dissasociate completely so there aren't a lot of ions in the solution to carry the charge. The salt helps somewhat, as it dissasociates completely.

You could also try a stronger acid. Hydrochloric acid is available as tile cleaner, or as 'muriatic acid' for cleaning concrete (from a hardware store). Sulfuric acid is available as drain clog remover from a hardware store (check the label to make sure it says sulfuric acid, not sodium hydroxide, which is also used for that) or as battery fluid from an automotive supply. Basically, you want to look at the solubility of the various ionic compounds. Copper chloride and copper sulfate, the copper salts of hydrochloric and sulfuric acids, are more soluble that the copper salts of organic acids like acetic acid and citric acid. Also since the strong acids dissasociate completely in water, there are lots of ions to carry charge. That makes a bath that carries a lot of copper, and can support a lot of current flow to move that copper quickly. The stronger acids also do a good job of removing crud from the surface of your workpiece.

I refreshed my memory a bit about what the sugar is for as well. It looks like it's there to slow the bath down and prevent the growth of metal crystals, so that the plating is smoother and doesn't need as much polishing. That's why they call it a 'brightner', as the smoother surface is more reflective. I'd concentrate on getting a good solid plating first, then add a brightner if the plating wasn't shiny enough to polish. They're not really neccesary for thin plating.

A.

 

[Christian Klippel]

Hello,

as Andrew already said, the chemistry is quite important if you want a good result. While one can use a variety of acids for the bath, not all of them work equally well. Also, the copper anode is important. Dunno about the standards in your country, over here in Germany, electric permanent wiring (single stranded wires in the walls, for example) are usually made of almost pure copper. Also, copper pipes for water installations are pretty pure copper too.

The used current is important as well, better too low a current than too high. If it bubbles, you basically destroy the electrolyte.

Since i do electroplating quite a lot, for my self made through-plated PCB's, i can give you the recipe for a nice bath that i work with:

1700 ml H2O (distilled)
490 ml H2So4 38% (battery acid)
280 gr CuSo4 (copper sulfate)
300 mg NaCl (salt)
1 ml Tween 20

The NaCl is used to allow for a smoother deposit of the copper onto the target, giving a more shiny surface. The Tween 20 is used to lower the surface tension of the solution, so that it easily enters into holes. For the actual plating i use about 3.5 amperes on a PCB of 160x100mm size.

About the copper: a lot of copper stuff is actually an alloy of copper and other metal. During electroplating, the copper transfers to the cathode, but not the other metal. Instead, the other metal end's up as very fine "grains" in the bath. Those "grains" then stick to the cathode, giving a very uneven and fragile surface.

You may want to constantly move the cathode around, to get an more even deposit. This is because the electrolyte in close proximity to the cathode will "deplete" if it isn't moved around. If you are unsure about the copper anodes, first pack them into soft paper tissue, then into a cotton bag. This will filter out the unwanted "grains" that i spoke of above.

Start out with a really low current first. Increase it slightly if you want. If it is too high, the cathode starts to get dark. With even more current, you get bubbles.

To get a really strong bond between the surface of the cathode and the copper you are going to e-plate, you may want to micro-etch the cathode. That is, place it into a strong etchant for a few seconds, rinse it, then put it in the plating bath. This process will roughen up the cathode's surface, giving a bigger surface area.

Hope thats helps,

Chris

Edit: make sure that your power supply is suitable! The e-plating bath basically produces a short circuit between anode and cathode. If the supply pretends to be somewhat intelligent, it will shut down because of the short it detected. You may not notice that because there will be still some copper deposited on the cathode, simply due to the chemical processes.

 

[Brian-M]

Thanks for the info, It'll give me a lot to think about next time I'm wondering why it isn't working properly.

One thing I definitely had wrong was too much current. I've got that down so it's barely making bubbles anymore. I guess I'll have to start looking at different acids next.

I'm going to give the magnesium sulfate a good try. I don't know much about chemistry so I could be completely wrong, but I think the magnesium will end up being deposited on the cathode and replaced with copper from the anode, effectively transforming magnesium sulfate into copper sulfate.

(But if I see copper sulfate in the store, I'll probably get some too. )

Edit: make sure that your power supply is suitable! The e-plating bath basically produces a short circuit between anode and cathode. If the supply pretends to be somewhat intelligent, it will shut down because of the short it detected. You may not notice that because there will be still some copper deposited on the cathode, simply due to the chemical processes.

That's not a problem with my power supply. It has an electronic current limit of 1.2A that automatically drops the voltage exactly as far as necessary to prevent current from exceeding the limit. It never cuts out.

I've also worked out that if you want to use one of those commonplace plug-pack power supplies, running the power through the graphite in an ordinary writing pencil will prevent the power supply from over-loading. The pencil acts like a 20 or 25 ohm resistor, which is exactly what is needed. (6 Volts / 20 Ohms = 300mA. 9 Volts / 20 Ohms = 450mA. The better plug-pack power supplies are rated for 500mA.)

 

[jasonpatterson]

Copper sulfate is sold for killing tree roots in drain lines, you can find it at any hardware/home improvement store. Read the label to make sure that it doesn't contain other impurities.

 

[anor277]

Since you are using concentrated acids (muriatic acid is approx 38% (w/w), sulfuric acid (95-98%)) one valuable tip is to always add the acid to the water, not the water to the acid. A drop of water in conc. acid rapidly heats and poses a hazard (remember the saying "if you spit in acid it spits back").

You've got no chance of depositing magnesium metal from Epsom salts; magnesium metal is very active and any deposited will go back into solution without any current (the addition of sodium ions to the solution is the same sort of phenomenon; sodium metal would react with the water also).

 

[ferd burfle]

Brian, I suggest going to http://www.finishing.com and using the search function. The site is aimed primarily at industry but there's been a lot of experimenter questions posted in the archives. Like all new forums, I suggest reading and searching to get up to speed before posting.

ferd

 

[Brian-M]

Hey, I'm finally getting some good results!
The magic formula that works for me is...

• 8 Cups of Water
• 4 Tablespoons of Epsom Salts
• 2 Tablespoons of Tartaric Acid
• Between 20 and 50 Milliamps of Direct Current

My results aren't perfect yet. I'm practicing on some old cutlery I got from a second-hand store, and while the result is smooth and shiny, it doesn't have much hold, especially when it's fresh from the solution.

(Could it be that the metal is far too polished for this to work properly? But then again, food-grade stainless steel probably isn't the best substance to test this on.)

I tried reversing the polarity for a short time for a coin, and that produced a plating with good hold, but the finish was very dull. Maybe I left it in reverse too long?

Next I'm going to try cleaning the metal before plating by soaking it in a diluted acid bath, and see if that helps. It looks like I've still got a lot of trial and error ahead of me before I can look back on all this with a sense of accomplishment, and start wondering why the hell I bothered in the first place.

Anyone got any ideas how I can improve on these results, or how I can adapt this to work with other metals?

Since you are using concentrated acids (muriatic acid is approx 38% (w/w), sulfuric acid (95-98%)) one valuable tip is to always add the acid to the water, not the water to the acid. A drop of water in conc. acid rapidly heats and poses a hazard (remember the saying "if you spit in acid it spits back").

Well, given that the "concentrated" acids I've been using (Citric Acid and Tartaric Acid) are both food products found in the bakery section of my local supermarket, I doubt that the hazard they pose is very high.

But thanks for the tip, I'll remember that if I start playing around with the dangerous stuff.

You've got no chance of depositing magnesium metal from Epsom salts; magnesium metal is very active and any deposited will go back into solution without any current (the addition of sodium ions to the solution is the same sort of phenomenon; sodium metal would react with the water also).

You're absolutely right. With my original brew I used good old Sodium Chloride, and after a brief period of disgusting frothy green, it settled down into a beautiful Copper-Sulfate-Colored blue.

Now I'm using Epsom salts instead, the solution is perfectly clear. It looks just like plain water. Obviously I was completely wrong about the magnesium being replaced with copper as there's not a trace of blue to be seen. Still, somehow it still manages to work.

That's got me confused.

Copper sulfate is sold for killing tree roots in drain lines, you can find it at any hardware/home improvement store. Read the label to make sure that it doesn't contain other impurities.

I checked in two major stores today, but couldn't find Copper Sulfate in either. Maybe I'm looking in the wrong place.

 

[Madalch]

Now I'm using Epsom salts instead, the solution is perfectly clear. It looks just like plain water. Obviously I was completely wrong about the magnesium being replaced with copper as there's not a trace of blue to be seen. Still, somehow it still manages to work.

Magnesium ions are a lot more stable than copper ions. If there's a source of electrons around, copper ions will grab a couple and settle down as copper metal. Magnesium ions won't. You can't make them, not in aqueous solution, anyway.

 

[ferd burfle]

My results aren't perfect yet. I'm practicing on some old cutlery I got from a second-hand store, and while the result is smooth and shiny, it doesn't have much hold, especially when it's fresh from the solution.

(Could it be that the metal is far too polished for this to work properly? But then again, food-grade stainless steel probably isn't the best substance to test this on.)

I tried reversing the polarity for a short time for a coin, and that produced a plating with good hold, but the finish was very dull. Maybe I left it in reverse too long?

Next I'm going to try cleaning the metal before plating by soaking it in a diluted acid bath, and see if that helps. It looks like I've still got a lot of trial and error ahead of me before I can look back on all this with a sense of accomplishment, and start wondering why the hell I bothered in the first place.

Anyone got any ideas how I can improve on these results, or how I can adapt this to work with other metals?

Good cleaning of your substrate is always a necessary first step but bear in mind that your choice of substrate determines what you should use to preclean and also determines if you can plate directly on that substrate or if you need to plate on a thin "bridging" layer or "strike" of some other metal to get good adhesion. Some metals will not plate directly on some substrates. I'd make sure I was using the same substrate in each trial to begin with---the old cutlery you're using is probably stainless but even then the alloy might vary.

If you like trying different combinations just to see what happens, go for it. If you want to make progress more quickly, I suggest checking online references or your nearest technical school library. For example, see the third paragraph of Ted Mooney's reply on this page http://www.finishing.com/153/52.shtml .

ferd

 

[Brian-M]

Just been looking around at www.finishing.com, and I think I've found the reason why the copper won't stick to the cutlery I've been testing it on.

It's because the cutlery is stainless steel...

First, the knife may actually be stainless steel in which case it is impossible for you to plate it in this casual fashion.

The thing is, you can't successfully plate onto tarnish or a passive skin, you must plate on fresh, active metal -- but stainless steel passivates almost instantly.

I've only been able to get the copper to stick to a single spoon (must be a lower quality stainless than all the rest). Looks like I'll have to find something else to test this out on.

Here's a picture of my current set-up in action; much more elegant than the last one. That shiny looking knife you can see in there is now very brown, and getting browner by the second. (I just keep being amazed by how clear the solution is.)

 

[jasonpatterson]

I checked in two major stores today, but couldn't find Copper Sulfate in either. Maybe I'm looking in the wrong place.

It won't be labeled copper sulfate, but instead something like Root Killer. It's also sold for algae control in ponds. The root killer comes in a round plastic container usually, about 6 inches high and 3 in diameter, often white with a little plastic bagged information sheet around the top. It's right at the register in the Lowe's down the street from me.

 

[Brian-M]

It won't be labeled copper sulfate, but instead something like Root Killer. It's also sold for algae control in ponds. The root killer comes in a round plastic container usually, about 6 inches high and 3 in diameter, often white with a little plastic bagged information sheet around the top. It's right at the register in the Lowe's down the street from me.

I meant maybe I was looking in the wrong place in the store. I found some Yates Bluestone Copper Sulfate in another store today. There are a couple of things that have me confused. On the packet it says...

GUARANTEED ANALYSIS
Copper (Cu) as Copper Sulphate 25.0%
Sulphur (S) as Copper Sulphate 12.0%

So what about the other 63%?
(ETA: Just did some Googling. The blue form of copper sulfate is COPPER(II) SULFATE, PENTAHYDRATE, so the other 63% must be water.)

Also, after reading the box and checking their website it appears they recommend using it as a fertilizer. So it's a root killer AND a fertilizer?

I think I'm missing something. Checking the web, I found other places like this one selling it as a fertilizer too. Does it come in different forms, or is it a matter of quantity?

____________________________________________​

Anyway, I've copper plated a 20 cent coin. The result was a little patchy, but it's definitely copper plated. (Somehow, copper plating a coin that's supposedly 75% copper to begin with seems like cheating.)

I've attached a picture of a coin next to an unplated one, and a stainless steel spoon I've somehow managed to copper-plate most of.

 

[Madalch]

So what about the other 63%?

It's copper(II) sulphate pentahydrate. CuSO4.5H2O

The other 63% is oxygen and water.

 

[Brian-M]

It's copper(II) sulphate pentahydrate. CuSO4.5H2O

The other 63% is oxygen and water.

Ah! You answered the question for me while I was busy editing my post to say I'd found the answer.

 

[anor277]

Try heating the blue crystals with a hot air gun. The blue crystals should turn white as the water is driven off.

(edited for spelling).

 

[Andrew Wiggin]

Try heating the blue crystals with a hot air gun. The blue crystals should turn white as the water is driven off.

(edited for spelling).

Doesn't make a difference. He'll be dissolving them in water anyway. No need to dehydrate it first.

A

 

[anor277]

Doesn't make a difference. He'll be dissolving them in water anyway. No need to dehydrate it first.

A

If you don't find the dehydration reaction (with its associated colour change) fascinating, then don't do the experiment. Of course I was aware that the CuSO₄ hydrate was to be dissolved in water.