As promised, here is a write-up of the electroplating process. I'm hunting down a couple references. I'll edit it and insert them with a couple more pictures soon.
Enjoy!
Disclaimer: As always, do this at your own risk. There are chemicals involved so proper personal protective equipment (ppe) is a must. Always determine disposal methods prior to ordering materials and always dispose in accordance with your local regulations. This is in no way a guaranteed method to stop rust. This is provided for informational purposes only.
I know a lot of guys, especially in the rust belt get really tired of stripping and painting just to have the rust monster pop up again in a couple years. Here's a few parts I've done.
And for reference here's a shot with a plated (upper left spring plate), bare steel (overload riser), and as removed parts.
What I'm about to describe may not be a permanent solution, but I believe it will give you a few more years if nothing else.
Electroplating steel with zinc (also called galvanization or zinc anodization) has been done since the 1800's on large scales. In short, the zinc acts as a sacrificial anode keeping electrolysis from happening on the iron because it has a lower oxidation potential. It does eventually wear through as anyone who has seen a rusty barn roof will understand.
How electroplating works.
Electroplating is essentially moving metal from the anode to the cathode by applying a bias. The anode is the metal you want to move ( in this case zinc) while the cathode is the electrode where the anode metal is deposited. You are essentially pulling electrons from the anode and pushing them to the cathode. To balance the charge, metal ions travel through the solution to the cathode so charge balance is conserved. If you want to know more about the science, ask the inter web. Told you that much so we could figure out what goes where.
As with any surface treatment, be it paint or metal plating, preparation is key. I'm not going to go into detail about rust removal. Anybody interested in doing this will be doing that research anyway. I will mention a couple general methods. There is mechanical (media blasting, wire wheel, etc.), acidic (citric acid, phosphoric acid, etc.) keylation (molasses, Evaporust, etc), and electrolytic. There are combinations of those as well. Personally, I generally do blasting and phosphoric acid for the hard to reach places and pitted parts. Phosphoric acid is cheap and converts what isn't dissolved into iron phosphite rather than iron oxide. The main thing is your plated surface will only be as clean and smooth as the bare metal so don't expect miracles. In my case, I'm going for ~98% pristine metal. Since I'm going to prime and paint my parts, it's not worth it to me to kill myself on that last 2% when it's just being a pain to remove. The surface also needs to be clean and free of oil or grease which includes your fingerprints. That about takes care of metal prep.
Before we go any further, a word about hydrogen embrittlement. Hydrogen embrittlement is a condition that results from hydrogen diffusing into interstitial spaces in steel causing fracture points. Any time steel is subjected to an acid bath or a plating electrolysis system there is a risk of hydrogen embrittlement. Based on the research I have done, only steel with 145000 psi yield strengths (think approximately grade 5 fastener) or higher are actually susceptible. The cure for this is a proper baking procedure. Please see the proper ASME standard should you choose to plate something hardened. Do your research. I'm not going to make recommendations for liability reasons, but I will tell you that my suspension parts were baked at 375 F for about 4 hrs in the toaster oven.
Let's talk about the plating system.
I tried a few things to get to an adjustable power supply. I settled on a battery charger run through a variac (large variable resistor). A heavy duty dimming light switch should also do the job. The thing you need to remember is that you really don't need high voltage for this. 12v from the battery charger is way more than required. You can use it directly but I don't recommend it. Using the higher voltage will result in other chemistry happening namely production of hydrogen from electrolysis of the water. If you have a 6V setting on the charger, all the better. Any DC power source that is capable of enough current, will work. You can use wall worts if doing small parts. The current density needs to be about 140 mA per square inch of surface area. I typically don't bother calculating surface areas. I set the power based on a volt meter measuring between the anode and cathode. More on this later.
The next thing needed are the zinc anodes. This could be anything from boat anodes to a sheet of zinc metal. I bought a 12x12" sheet of zinc from amazon. The more pure the alloy the better but it's not ultra critical. I cut the zinc into 1" strips to make the anodes for the plating bucket.
Strictly speaking, you only need 1 anode however, the plating process is really a line-of-sight process, so the side facing the anode will get much more on it than the other sides so really, you want multiple anodes in the plating container.
I chose a 5 gallon bucket with a screw on lid so I could close it up easy when not in use. In my bucket I used 4 anodes spaced around the bucket. I also connected 2 of them with a cross piece in the bottom to cover the bottom edge of parts.
You can connect then with aluminum rivets but not steel or zinc plated fasteners because they will dissolve. The aluminum may over time as well but so far so good. Connect all the anodes together with wire (12ga is overkill but convenient). You don't really want the copper in the bath on the anode side because if the voltage gets high enough the copper will start trying to plate out and cause problems.
Alright, we have the container, the anodes and the power supply, we need a way to hang the parts in the bath. 12ga solid wire seems to work pretty well. Might need more than one hook but it works alright. I hang it over a length of copper water line but anything conductive will work.
Be careful to not let the anodes or anode wires touch the conductive hanger, otherwise known as the cathode. It will create a short circuit.
Now for the plating bath. Here is what I used. I adapted the recipe from one I found on the web. A standard Wally World food scale will measure this stuff. Measuring to within a few grams should be close enough.
For each gallon of water:
253 g Epsom salts
84.4 g zinc sulfate
168.8 ml white vinegar
1cup of corn syrup.
Mix it together until most everything is dissolved. If you can use warm water it will go faster. I used water from my reverse osmosis system. You can use tap water but the less extra metals you start with the better. Distilled would be optimal but not required.
The Epsom salts are magnesium sulfate. It serves mainly to provide spectator ions to the bath to increase conductivity. The zinc sulfate is there to pre-load the bath with zinc ions. It's not 100% necessary but brings the bath zinc concentration up without having to dissolve the anodes to just bring the zinc concentration to equilibrium making the bath efficient from the start. It's available from Amazon at reasonable purity. 2lbs is more than enough for 5 gallons. The vinegar adjusts the pH to around 4 which keeps the metal salts dissolved. If the pH goes basic (above 7) the metal salts will crash out and cause problems. You are probably wondering about the corn syrup. It is actually a brightening agent. The fructose acts as a chelating agent to mediate the transfer of the zinc ions to the parts making the surface smoother and less porous. There are lots of brightening agents out there. Since I'm not all that concerned about bright coatings, I just went with the corn syrup. It's cheap and non-toxic.
Okay, I think we are about ready to start. Here is what the part looks like before it goes into the bucket.
With the part suspended in the bath, making sure it's not touching any of the anodes, connect the positive lead to the anodes and the negative lead to the cathode. Turn the variable resistor to off or 0% power and plug in the power supply. Slowly increase the %power until you start seeing a voltage across the anode and cathode. Personally, I like to keep it under 2 volts. Anything over 2 volts is just producing hydrogen. It will plate faster but the surface may be rougher. There should be some bubbles form on the part. After a few minutes, the part should start to turn a bluish color. I typically run parts for about 30 min then rotate them a bit or turn them over and run for another 15-30 minutes depending on what the part looks like. One note, when dark spots begin forming, those are high field areas where the plating is getting really thick. You want to try to minimize that by using a couple hooks to hang the parts. It just makes the parts come out more even.
When you pull them out of the bath, they will be a dull bluish color.
I typically just scrub them up well with a scotch brite pad. You'll notice that the dull blue will fade and start the brighten up to a silvery color.
If you are planning to polish the parts you will want to burnish the part and strike it again (replate). From what I have read, brass brush and some mild compound do well for burnishing the parts prior to polishing.
Once you are done, just disconnect the power leads. If I'm going to be away from it for a while, I'll pull the anodes out and seal the bucket up. The solution should stay good for a long time. You can always top it up with a little water as you use it. If it gets cloudy, try a little vinegar or check the pH before discarding it. You loose very little liquid when you pull the parts out if you let it drip a little after you remove it.
Now post processing. I put all my stuff in the oven as I mentioned above. They should be ready for primer at this point as the scotchbrite should have removed any loose stuff and it should be rough enough to accept the primer. Be sure your primer is compatible if you are paintin
Sent from my iPhone using Tapatalk
Enjoy!
Disclaimer: As always, do this at your own risk. There are chemicals involved so proper personal protective equipment (ppe) is a must. Always determine disposal methods prior to ordering materials and always dispose in accordance with your local regulations. This is in no way a guaranteed method to stop rust. This is provided for informational purposes only.
I know a lot of guys, especially in the rust belt get really tired of stripping and painting just to have the rust monster pop up again in a couple years. Here's a few parts I've done.
You must be registered for see images attach
And for reference here's a shot with a plated (upper left spring plate), bare steel (overload riser), and as removed parts.
You must be registered for see images attach
What I'm about to describe may not be a permanent solution, but I believe it will give you a few more years if nothing else.
Electroplating steel with zinc (also called galvanization or zinc anodization) has been done since the 1800's on large scales. In short, the zinc acts as a sacrificial anode keeping electrolysis from happening on the iron because it has a lower oxidation potential. It does eventually wear through as anyone who has seen a rusty barn roof will understand.
How electroplating works.
Electroplating is essentially moving metal from the anode to the cathode by applying a bias. The anode is the metal you want to move ( in this case zinc) while the cathode is the electrode where the anode metal is deposited. You are essentially pulling electrons from the anode and pushing them to the cathode. To balance the charge, metal ions travel through the solution to the cathode so charge balance is conserved. If you want to know more about the science, ask the inter web. Told you that much so we could figure out what goes where.
As with any surface treatment, be it paint or metal plating, preparation is key. I'm not going to go into detail about rust removal. Anybody interested in doing this will be doing that research anyway. I will mention a couple general methods. There is mechanical (media blasting, wire wheel, etc.), acidic (citric acid, phosphoric acid, etc.) keylation (molasses, Evaporust, etc), and electrolytic. There are combinations of those as well. Personally, I generally do blasting and phosphoric acid for the hard to reach places and pitted parts. Phosphoric acid is cheap and converts what isn't dissolved into iron phosphite rather than iron oxide. The main thing is your plated surface will only be as clean and smooth as the bare metal so don't expect miracles. In my case, I'm going for ~98% pristine metal. Since I'm going to prime and paint my parts, it's not worth it to me to kill myself on that last 2% when it's just being a pain to remove. The surface also needs to be clean and free of oil or grease which includes your fingerprints. That about takes care of metal prep.
Before we go any further, a word about hydrogen embrittlement. Hydrogen embrittlement is a condition that results from hydrogen diffusing into interstitial spaces in steel causing fracture points. Any time steel is subjected to an acid bath or a plating electrolysis system there is a risk of hydrogen embrittlement. Based on the research I have done, only steel with 145000 psi yield strengths (think approximately grade 5 fastener) or higher are actually susceptible. The cure for this is a proper baking procedure. Please see the proper ASME standard should you choose to plate something hardened. Do your research. I'm not going to make recommendations for liability reasons, but I will tell you that my suspension parts were baked at 375 F for about 4 hrs in the toaster oven.
Let's talk about the plating system.
I tried a few things to get to an adjustable power supply. I settled on a battery charger run through a variac (large variable resistor). A heavy duty dimming light switch should also do the job. The thing you need to remember is that you really don't need high voltage for this. 12v from the battery charger is way more than required. You can use it directly but I don't recommend it. Using the higher voltage will result in other chemistry happening namely production of hydrogen from electrolysis of the water. If you have a 6V setting on the charger, all the better. Any DC power source that is capable of enough current, will work. You can use wall worts if doing small parts. The current density needs to be about 140 mA per square inch of surface area. I typically don't bother calculating surface areas. I set the power based on a volt meter measuring between the anode and cathode. More on this later.
The next thing needed are the zinc anodes. This could be anything from boat anodes to a sheet of zinc metal. I bought a 12x12" sheet of zinc from amazon. The more pure the alloy the better but it's not ultra critical. I cut the zinc into 1" strips to make the anodes for the plating bucket.
Strictly speaking, you only need 1 anode however, the plating process is really a line-of-sight process, so the side facing the anode will get much more on it than the other sides so really, you want multiple anodes in the plating container.
I chose a 5 gallon bucket with a screw on lid so I could close it up easy when not in use. In my bucket I used 4 anodes spaced around the bucket. I also connected 2 of them with a cross piece in the bottom to cover the bottom edge of parts.
You must be registered for see images attach
You can connect then with aluminum rivets but not steel or zinc plated fasteners because they will dissolve. The aluminum may over time as well but so far so good. Connect all the anodes together with wire (12ga is overkill but convenient). You don't really want the copper in the bath on the anode side because if the voltage gets high enough the copper will start trying to plate out and cause problems.
Alright, we have the container, the anodes and the power supply, we need a way to hang the parts in the bath. 12ga solid wire seems to work pretty well. Might need more than one hook but it works alright. I hang it over a length of copper water line but anything conductive will work.
You must be registered for see images attach
Be careful to not let the anodes or anode wires touch the conductive hanger, otherwise known as the cathode. It will create a short circuit.
Now for the plating bath. Here is what I used. I adapted the recipe from one I found on the web. A standard Wally World food scale will measure this stuff. Measuring to within a few grams should be close enough.
You must be registered for see images attach
For each gallon of water:
253 g Epsom salts
84.4 g zinc sulfate
168.8 ml white vinegar
1cup of corn syrup.
Mix it together until most everything is dissolved. If you can use warm water it will go faster. I used water from my reverse osmosis system. You can use tap water but the less extra metals you start with the better. Distilled would be optimal but not required.
The Epsom salts are magnesium sulfate. It serves mainly to provide spectator ions to the bath to increase conductivity. The zinc sulfate is there to pre-load the bath with zinc ions. It's not 100% necessary but brings the bath zinc concentration up without having to dissolve the anodes to just bring the zinc concentration to equilibrium making the bath efficient from the start. It's available from Amazon at reasonable purity. 2lbs is more than enough for 5 gallons. The vinegar adjusts the pH to around 4 which keeps the metal salts dissolved. If the pH goes basic (above 7) the metal salts will crash out and cause problems. You are probably wondering about the corn syrup. It is actually a brightening agent. The fructose acts as a chelating agent to mediate the transfer of the zinc ions to the parts making the surface smoother and less porous. There are lots of brightening agents out there. Since I'm not all that concerned about bright coatings, I just went with the corn syrup. It's cheap and non-toxic.
Okay, I think we are about ready to start. Here is what the part looks like before it goes into the bucket.
You must be registered for see images attach
With the part suspended in the bath, making sure it's not touching any of the anodes, connect the positive lead to the anodes and the negative lead to the cathode. Turn the variable resistor to off or 0% power and plug in the power supply. Slowly increase the %power until you start seeing a voltage across the anode and cathode. Personally, I like to keep it under 2 volts. Anything over 2 volts is just producing hydrogen. It will plate faster but the surface may be rougher. There should be some bubbles form on the part. After a few minutes, the part should start to turn a bluish color. I typically run parts for about 30 min then rotate them a bit or turn them over and run for another 15-30 minutes depending on what the part looks like. One note, when dark spots begin forming, those are high field areas where the plating is getting really thick. You want to try to minimize that by using a couple hooks to hang the parts. It just makes the parts come out more even.
When you pull them out of the bath, they will be a dull bluish color.
You must be registered for see images attach
I typically just scrub them up well with a scotch brite pad. You'll notice that the dull blue will fade and start the brighten up to a silvery color.
You must be registered for see images attach
If you are planning to polish the parts you will want to burnish the part and strike it again (replate). From what I have read, brass brush and some mild compound do well for burnishing the parts prior to polishing.
Once you are done, just disconnect the power leads. If I'm going to be away from it for a while, I'll pull the anodes out and seal the bucket up. The solution should stay good for a long time. You can always top it up with a little water as you use it. If it gets cloudy, try a little vinegar or check the pH before discarding it. You loose very little liquid when you pull the parts out if you let it drip a little after you remove it.
Now post processing. I put all my stuff in the oven as I mentioned above. They should be ready for primer at this point as the scotchbrite should have removed any loose stuff and it should be rough enough to accept the primer. Be sure your primer is compatible if you are paintin
Sent from my iPhone using Tapatalk
