I have been doing online searches on refinishing aluminum parts for wheels and intakes that I have. This search quickly introduced me to electrolysis for ferrous or carbon metals., because that is how the internet works. Anyway, I found that I could do this science because it really is pretty easy, and no brain injuries will be caused by my explanation because I'm going to explain it like I like it explained to me; as if you are talking to a six year old. Items I used: 1. Plastic tub or bucket, 5 gallons or better 2. A 2x4 or at least a piece of wood strong enough to support your work piece and cross the plastic container 3. A battery charger 4. Two wire leads with aligator clips on both ends 5. Car battery 6. Wire coat hanger to cannibalize to support the anode and the cathode 7. Sodium carbonate, aka Arm & Hammer washing soda, not baking soda, I got mine at Ace Hardware 8. Piece of scrap steel to use as an anode
The reason you use plastic tubs and wood in this experiment is for safety and to insulate your anode and cathode and of course because you want good results. Set up your wood "bridge" to go over the plastic container with the coat hanger wire acting as a hook to support the piece you want to de-rust, or cathode. Rig up another bit of coat hanger wire to support a piece of scrap steel, or anode, that you will be sacrificing for the other piece. Now you know what the cathode and anode are. Once you have your cathode and anode suspended in your plastic container, be sure they won't come into contact with each other. Pour room temperature water into the container and be sure the cathode is completely covered. Add the sodium carbonate and stir, I used half a cup for five gallons and it may have been overkill. Additionally, I used a fish tank bubbler to agitate the water to keep the sodium carbonate in solution, because I' m meticulous that way, says my wife. Attach the alligator clips to the coat hangers supporting the cathode and the anode (see diagram). Set up you battery charger to the battery but do not plug it in yet. Attach the cathode's alligator clip to the negative battery charger post clamp. Attach the anode' s alligator clip to the positive battery charger post clamp. Confirm the cathode and anode are submerged in the solution. Plug in the battery charger and observe the cathode, you should see it start to gently "fizz".
That fizz is actually the exchange of ions, protons, and morons, as Amos n' Andy once said. It is also pure hydrogen and oxygen. Because gasses are a result of this science experiment, and they are explosive, do this outside. Also, DO NOT use stainless or galvanized steel as your anode, or support wires for the cathode or anode, they make poisonous gasses. The anode will look horrible, like it has barnicles on it, really gross looking. I let this fizz for 24 hours. Check out the diagram below for visual clarification of what I wrote. I typed this slow because I know some of you don't read so fast.
ZINC PLATING Once I got the piece I used de-rusted, I rinsed it off and set up the zinc plating operation using the same equipment. I did change the solution however; once again using room temperature water, sodium carbonate, and the addition of vinegar for the acid. I guess that is to etch the metal, but I do not know for sure why. Perhaps we have some real science boffins here that can tell us. Once again, the piece I de-rusted was the cathode, but I used a real zinc anode that is for an ice machine as the sacrificial piece. I got it online through Home Depot for $9 about, I had to buy it online because they don't normally carry them. Whats cool about it is that it comes with a wire lead attached that is insulated.
Once again, go through the same set up as you did for the de-rusting. You will see the same fizz, and of course do it outside and don't huff the fumes. I let it fizz for about an hour, I have no idea if that was overkill or not enough, time will tell I guess.
As you can see, this is a sbc lower alternator bracket, and it was black painted with some surface rust all over it. I have to say that this wasn't the best piece for me to zinc plate as it has had it rough since birth. Look at all the tool marks from the factory and from being used, so it may be clean and coated, but it ain't pretty. I "polished" the right half of the bracket using a dremel tool with a brass rotary brush, the other side was left alone. The lighting wasn't that great today, cloudy, but you can see it is better on the right side than on the left. I tried to use the buffing wheel for the harbor freight "dremel", but there was no suitable arbor to use, so this is as far as I got.
I plan on expanding upon this experiment; I have a cool aftermarket steering wheel that needs a bit of de-rusting as the foundation. I did all of this to prepare to work on the wheel anyway. Further research reveals that if I add a layer of copper the results should be much better. That and having a much smoother surface should yield better results. I'll also see if I can't get ahold of a better buffer and some better rouge than the white toothpaste I used. So stay tuned for the steering wheel resto thread, that is where I will go over the copper plating.
Gone but not forgotten; I cherish the times my dad took me downtown to see them, this was back in the days of Gordie Howe. Those were days, even though the team wasn't that great, they had a loyal fan base. I wonder if Gordie knows anything about electrolysis?
Thank you for the basic easy to understand how to. Our local Lowe's store has the zinc sacrificial anodes in the water heater department. They come in various sizes and are not expensive. I'll be following your thread.
I've done the rust removal for years now, but never the zinc plating. I know derusting generates hydrogen gas, what does the zinc plating generate?
Hydrogen and possibly chlorine depending upon your anode's composition. Here's some skull splitting stuff to read about the science of it all: http://mysite.du.edu/~jcalvert/phys/elechem.htm#Oxid Electroplating It happens that the cheap and strong metals, such as steel, are subject to rapid corrosion, while metals that resist corrosion, such as silver, gold, copper, tin, zinc, lead and nickel, are either weak, or expensive. The benefits of both can be realized by coating the strong metal with the unreactive metal. This protection is provided either by the fundamental unreactivity of the coating (gold, silver and copper), the formation of a protective layer (nickel, zinc, tin, lead), or cathodic protection (zinc on steel). A layer that does not provide cathodic protection (like tin on steel) must be sound and continuous, since corrosion may actually be promoted by the coating at such "pinholes." Methods of applying the coating are: (a) hot-dipping in the molten protective metal; (b) cementation--forming a surface alloy without melting; (c) cladding--fusing the protective layer to the metal before it is rolled; (d) sputtering from a cathode in vacuum, or deposition from a vapor; and (e) electroplating. We will discuss only the last method here. See articles on the individual metals for examples of the other methods. In electroplating, the object to be coated is made the cathode in an electrolytic cell. The electrolyte contains an ion that is reduced to the metal at the cathode surface in proportion to the current passing through the cell. One equivalent weight (atomic weight divided by the electrovalence) is deposited for each faraday of charge at an electrolytic efficiency of 100%. The anode may be the same metal that is being plated, where the metal ion is oxidized and replenishes the electrolyte automatically. Alternatively, the anode may be inert, and additional ions added as required. This is the case in chromium plating, where chromic acid is added continually. The voltage required is usually low, only a few volts, and the current density adjusted to give the best plating. Current densities of about 5-50 A/sq.ft. are not exceptional. Reduction of H+ ion to hydrogen gas at the cathode competes with reduction of the metal ion. In acidic solution, only a few metals, such as Cu, Ag and Au, are beneath hydrogen in the electrochemical series, and can be successfully deposited. If the solution is alkaline, the reduction potential of hydrogen is then -0.828V, permitting many more metals to be reduced at the cathode, including Zn, Sn, Cd, Cr and Ni, usually from complex ions, such as cyanide, stannate and chromate. The pH must usually be carefully controlled to ensure the proper electrode reactions. The complex ions supply a controlled small concentration of positive metal ions for reduction, making a better and more uniform deposit. The first step in any coating process, and especially electroplating, is the preparation of the object to be coated. There are three steps: (1) degreasing; (2) removal of oxides; and (3) surface mechanical preparation. Degreasing can use a solvent such as TCE (trichloroethylene). TCE is noninflammable, but must be used in a closed system since it is hazardous. An alternative or additional method is electrolysis in an alkaline solution of sodium carbonate, with small amounts of sodium hydroxide, trisodium phosphate and borax, at a current density of about 10 A/sq.ft. The object is made the cathode, and the copious emission of hydrogen gas gives a thorough cleaning. Next, any surface oxide must be removed, or it will react with the coating to give a weak area that may separated from the substrate. For steel, wire-brushing followed by pickling in a 4%-5% H2SO4 solution at 65-75°C is satisfactory. Brass is pickled in dilute sulphuric and hydrochloric acids mixed with a little nitric. A dip in 2%-10% H3PO4 produces a beneficial phosphatic film. Finally, the surface is roughened if this helps the adherence of the plating. The plated surface comes from the bath in a matte form, and must be polished if it is to be shiny. Sometimes protective coatings are added as well. Chromium plate is always porous, so it cannot be used directly over steel because of the danger of pinhole corrosion. The electrolyte is chromic acid (chromium trioxide) in sulphuric acid, with an inert anode. The pH and concentration must be carefully controlled to avoid reduction of hydrogen. Chromium is usually plated over nickel, which does give a dense, impervious surface and protects the steel. Nickel is plated from an electrolyte of NiSO4, NiCl2 and H3BO3 at 50-60°C, with carefully controlled pH. Aluminium would make a good coating, but it cannot be reduced electrolytically from an aqueous solution because it is above hydrogen for any pH and concentration. If aluminium were not passivated by its coating of Al2O3, it would release hydrogen when dipped in pure water. It is this that prevented the easy winning of aluminium by electrolysis, as in the case of copper.
EMISSIONS http://www3.epa.gov/ttnchie1/ap42/ch12/final/c12s20.pdf Zinc Electroplating - The most widely used zinc plating solutions are categorized as acid chloride, alkaline noncyanide, and cyanide. The most widely used zinc alloys for electroplating are zinc-nickel, zinccobalt, and zinc-iron. Zinc plating baths contain 15 to 38 g/L (2.0 to 5.0 oz/gal) of acid chloride zinc, 6.0 to 23 g/L (0.80 to 3.0 oz/gal) of alkaline noncyanide zinc, or 7.5 to 34 g/L (1.0 to 4.5 oz/gal) of cyanide zinc. Acid zinc-nickel plating baths contain 120 to 130 g/L (16 to 17 oz/gal) of zinc chloride and 110 to 130 g/L (15 to 17 oz/gal) of nickel chloride. Alkaline zinc-nickel plating baths contain 8.0 g/L (1.1 oz/gal) of zinc metal and 1.6 g/L (0.21 oz/gal) of nickel metal. Current densities range from 5.0 to 40 A/m2 (0.46 to 3.7 A-ft2) and 20 to 100 A/m2 (1.9 to 9.3 A/ft2) for acid and alkaline baths, respectively. Acid zinc-cobalt plating baths contain 30 g/L (4.0 oz/gal) of zinc metal and 1.9 to 3.8 g/L (0.25 to 0.51 oz/gal) of cobalt metal. Alkaline zinc-cobalt plating baths contain 6.0 to 9.0 g/L (0.80 to 1.2 oz/gal) of zinc metal and 0.030 to 0.050 g/L (0.0040 to 0.0067 oz/gal) of cobalt metal. Current densities range from 1.0 to 500 A/m2 (0.093 to 46 A-ft2) and 20 to 40 A/m2 (1.9 to 3.7 A/ft2) for acid and alkaline baths, respectively. Acid zinc-iron plating baths contain 200 to 300 g/L (27 to 40 oz/gal) of ferric sulfate and 200 to 300 g/L (27 to 40 oz/gal) of zinc sulfate. Alkaline zinc-iron plating baths contain 20 to 25 g/L (2.7 to 3.3 oz/gal) of zinc metal and 0.25 to 0.50 g/L (0.033 to 0.067 oz/gal) of iron metal. Current densities range from 15 to 30 A/m2 (1.4 to 2.8 A-ft2). 12.20.2 Emissions and Controls2-3,43-44 Plating operations generate mists due to the evolution of hydrogen and oxygen gas. The gases are formed in the process tanks on the surface of the submerged part or on anodes or cathodes. As these gas bubbles rise to the surface, they escape into the air and may carry considerable liquid with them in the form of a fine mist. The rate of gassing is a function of the chemical or electrochemical activity in the tank and increases with the amount of work in the tank, the strength and temperature of the solution, and the current densities in the plating tanks. Air sparging also can result in emissions from the bursting of air bubbles at the surface of the plating tank liquid. Emissions are also generated from surface preparation steps, such as alkaline cleaning, acid dipping, and vapor degreasing. These emissions are in the form of alkaline and acid mists and solvent vapors. The extent of acid misting from the plating processes depends mainly on the efficiency of the plating bath and the degree of air sparging or mechanical agitation. For many metals, plating baths have high cathode efficiencies so that the generation of mist is minimal. However, the cathode efficiency of chromium plating baths is very low (10 to 20 percent), and a substantial quantity of chromic acid mist is generated. The following paragraphs describe the methods used to control emissions from chromium electroplating. These methods generally apply to other types of plating operations as well.
Yeah, I think I see why electroplating is a regulated activity. You just practically wrote a dictionary of toxins.
I've also seen to use graphite welding rods (Grainger usually carries them) as your anode, they don't get quite so crummy-looking and you can reuse them a lot easier.
Down the river a bit. Born in Middletown. Grew up in Haddam. Lived in Portland and South Glastonbury, too. Worked at New Britain General Hospital for many years.
From personal experience: use a fuse! I had my set-up running back in January and I didn't notice the part slip off the hanger. It contacted the sacrificial anode. I saw the smoke in the air, but by then the wires had melted and one of the cables had melted a slot in the battery case, allowing acid to seep onto the garage floor. USE A FUSE!
That is good advice, and precisely why the anode is positioned away from the work flush against the wall of the tub. The anode itself is a 4" x 4", 1/8 piece of plate secured with wire the same thickness.
So how did the steering wheel turn out? Sent from my cell phone when I shoulda been working, using the H.A.M.B. mobile app
Pretty nice, I'm away from home so I can't get a pic right now, some of the corrosion left little pits, but at least the corrosion is gone and the pits are not too noticeable.
The Jalopy Journal
