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Thread: DIY Zinc Plating for Donor Nuts and Bolts

  1. #1
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    DIY Zinc Plating for Donor Nuts and Bolts

    If you have rusty donor parts and have not read the thread on old school electrolytic de-rusting, then do yourself a favor and take a quick look... several forum members have posted pictures that are almost too good to believe... but the process works as advertised.

    One problem with electrolytic de-rusting is that the part comes out of the de-rusting bucket with no protective oxide layer, so you must immediately do something to passivate or seal the exposed metal or it will start rusting before your eyes. Painting works great on larger parts, but not so well on nuts and bolts, and certainly not very well on threads. After considerable study, I decided to try home-brew zinc plating.

    As it turns out, zinc plating is pretty easy to do at home, with easy to obtain materials that are not particularly dangerous. The washer shown below was my very first try, and developed a completely usable protective coating in about twenty minutes.

    DSC_1040.jpg


    If you want to give it a try, here's what you will need...

    1) A supply of nearly pure zinc metal. I bought a 30 ft long by 2.5 inch wide roll of zinc at my neighborhood home improvement store (about $30). It is sold in the roofing supply isle to keep moss from growing on your roof. But check around first because not all stores have it, and most employees have never heard of it. I verified that a nearby store had it by checking inventory on their web site. They had a little trouble finding it, but since the computer said they had it they kept looking until it was located.

    2) A low voltage power supply that can be adjusted from about 0.5 Volts to about 3 Volts. A rheostat can be used to cut the voltage if all you have is a 12 Volt supply.

    3) Vinegar from the grocery store. Find a bottle that says "Dilluted to 5% Acidity". Vinegar is actually a mild solution of acetic acid and is what slowly dissolves the zinc metal into solution.

    4) Epsom Salt from the grocery store or pharmacy. Epsom salt is Magnesium Sulfate and is the conductive "electrolyte" of the plating solution.

    5) Sugar from the grocery store (plain old table sugar). Sugar is the "Brightener" of the plating solution. It actually interferes with the formation of zinc crystals, causing many smaller crystals to form on the surface instead of fewer larger crystals, thereby improving a frosty looking surface to a smoother more reflective one.

    6) You will also need several clean plastic containers to mix and store the plating solution and do the actual plating.

    The plating solution recipe (which you can scale up or down as you like):
    1 liter of vinegar (5%)
    100 grams Epsom Salt
    120 grams sugar
    8 - 10 square inches of zinc pieces

    Add the Epsom Salt and sugar to room temperature vinegar and stir until dissolved. Add the zinc pieces and leave lightly covered for 24 hours.

    You may not see any bubbling for the first few hours, but by the end of the first day you should see small bubbles coming off the zinc pieces. This is the zinc metal being converted to soluble zinc acetate while liberating hydrogen gas. Don't tightly cap the solution or the pressure from the hydrogen gas will build up and the container may rupture. The longer you wait for the zinc to dissolve, the faster (and some say better) the plating will build up when you start your first run. Once the run starts, you are actually dissolving zinc off the anode at the same rate you are plating zinc onto the cathode, so the zinc in solution should not get depleted.

    To actually plate something, make an anode (+ terminal) of zinc metal, and attach the cathode (- terminal) to the part you want zinc plated. The submerged area of the anode should be a little larger than the area of the part being plated.

    DSC_1030.jpg

    If your solution has a sufficient amount of dissolved zinc acetate then you will see the part start to turn zinc colored almost immediately.

    DSC_1032.jpg

    The voltage should be adjusted for about 65 mA (milli-Amps) per square inch of part being plated. Of course most of us do not have a milli-ammeter so some experimentation should be expected. The goal is to try different amounts of current and select the setting that gives the nicest looking coating. If the voltage is too high the edges of the part will look uneven, or have a burned look. If the voltage is too low the plating run will take too long and the finish may be more frosted or dull looking. If the voltage is set correctly, only a very slight amount of bubbling will occur. Violent bubbling means the voltage is too high.

    After 10 minutes or so remove the part and give it a light rub with a ScotchBright pad to shine it up. If the plating looks too thin you can stick it back into the solution for another run.

    It is preferable to do a sequence of several short (10 - 15 minute) runs with a rub between each, than to do one long continuous run in the plating solution. This intermediate polishing step is called "carding" in the plating literature. I don't know why.

    The most important preparation step is cleaning the part. The plating will not stick to fingerprint oil, dirt, or any contamination. Most commercial plating shops have very thorough cleaning steps with a final acid etch bath just before the plating run. Scrub the part with detergent, rinse well, and wear gloves to keep the part clean. This is apparently the most common cause of peeling in DIY endeavors.

    If you try it, please let us all know how it goes.

    Jeff

  2. #2
    Senior Member DodgyTim's Avatar
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    I had a go at this a few months ago, and had good results from a corrosion point of view, lousy from the appearance viewpoint. I used nearly the same solution, 3v, and short bursts with scotchbright polishing in between coats.
    The coating I did looked like a dry primer coat, so would need to be overcoated with something to pretty it up.
    I left the parts outside for 2 months and there is no rust, but our climate is mild, I'm not sure how they'd hold up to salted roads.

    I once worked at and electrowinning zinc refinery, and the zinc sheets ther were nice and shiny, so i am going to retry this using their electrolyte, which is typically 140 to 180 g/L sulphuric.

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    How well does it deal with bolt and nut threads? Does buildup cause any interference problems on the mating surfaces? Is the zinc coating easily abraded with normal wear?
    I'm not sure what the typical coating thickness ends up being.

    This seems like a great idea to use in conjunction with paint or powder if it holds up over time.

  4. #4
    Senior Member DodgyTim's Avatar
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    Coarse threads were no problem for fit and the nut didn't remove the plating as it was threaded on. I didn't plate anything with a fine thread.

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    Senior Member Frank818's Avatar
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    The mixture can be 30mg of Zinc Sulfate for every 100ml of water.
    Use a pure zinc plate on the positive side and your part on the negative and swirl the mixture very often while the part is plating. Long process with steady follow-ups and not recommended for bigger parts, as you will need a much bigger mixture which may cost quite some more. Maybe Jeff's mixture costs less.
    Last edited by Frank818; 05-14-2014 at 08:58 AM.
    Frank
    818 chassis #181 powered by a '93 VW VR6 Turbo GT3582R
    Go-karted Aug 5, 2016 - Then May 19+21, 2017
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    [QUOTE=Frank818;153279]
    Use a pure zinc plate on the negative side and your part on the positive...

    Frank: You've got your polarity swapped... the zinc plate (anode) is positive and the part (cathode) is negative.

  7. #7
    Senior Member Frank818's Avatar
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    Jesus I always make that typo. Edited my post, tnx.
    Frank
    818 chassis #181 powered by a '93 VW VR6 Turbo GT3582R
    Go-karted Aug 5, 2016 - Then May 19+21, 2017
    Tracked May 27/July 26, 2017
    Build time before being driveable on Sep 27, 2019: over 6000h
    Build Completed Winter 2021

  8. #8
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    There are many ways to plate zinc, and they generally fall into three categories.... cynanide based formulations, those using a strong alkali solution, and those using a weak acid.

    Cyanide formulations are a non-starter. I'm not crazy about the idea of a strong alkali formula either, but the results might warrant some investigation if you are looking for a nice finish.

    Personally... I am comfortable with vinegar, epsom salt, and sugar as reagents in my own home. But I am not looking for a show quality finish. All I want is galvanic protection for my de-rusted nuts and bolts, so my threshold for an acceptable looking finish is admittedly pretty low.

    I am going to continue experimenting with current density and run time to try getting the the brightest shine possible, but I will still consider the whole affair a success if I get dull frosty looking bolts that don't rust.

    Jeff

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    Quote Originally Posted by JeffS View Post
    2) A low voltage power supply that can be adjusted from about 0.5 Volts to about 3 Volts. A rheostat can be used to cut the voltage if all you have is a 12 Volt supply.
    Jeff
    How many amps do you need? AC or DC?
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  10. #10
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    Hi guys I cleaned all my hardware from the donor with jungle jakes degreasing solution and steam cleaned. The parts came out very clean but the original greenish coating was Trashed and looks terrible!!
    I called several plating shops in town that do zinc phosphate treatment. The parts will turn out goldfish, blue or silver and the costs are 55 bucks for a minimum batch, which is more hardware than our cars will have in them. The place is called Professional plating in Brillion Wisconsin.
    Once I have the car mocked up and torn down for painting and Final assembly I'll send all the hardware out for this treatment.
    To get the show quality finish there are multiple coatings involved and processes.
    Best let the professionals do this for such a low cost!

    Here is their info
    http://www.proplating.com/finishes-barrel.php


    BARREL ZINC


    Smaller parts, including fasteners, hardware, and metal stampings can be efficiently and economically handled in Professional Plating's Barrel Zinc Plating line.

    Our Barrel Plating line is fully automated and digitally controlled with special programs, and individual recipes to manage cleaning, plating, and chromating operations. Strict compliance with our Statistical Process Control ensures the quality of every barrel plating project we do.

    Our 21-barrel, 27-station line enables us to process thousands of pounds of material every day. With this exceptional capacity we can provide rapid turnaround time. For urgent projects, we can turn the work around even faster with no loss of quality.


    Barrel Line Standards:

    Coatings per ASTM B633 specifications
    Zinc Chloride bath system
    Clear, Pro Dura Clear, and Yellow (All Hex-free)
    Olive drab chromate, and dyes available
    Pro-Dura, a proprietary high corrosion black zinc (Hex-free)
    All finishes are RoHS compliant except Olive Drab.
    System is fully automated, and programmable
    Statistical Process Control ensures consistent quality


    ASTM B 633 Types, Classifications, and Service Conditions:

    Type I -- As plated without supplementary treatment
    Type II -- With colored conversion coatings
    Type III -- With colorless chromate conversion coatings

    Classification
    Number
    Minimum
    Thickness
    Service
    Condition
    Fe/Zn 25 25 um .001" SC 4 (very severe) – Exposure to harsh conditions such as moisture, cleaners, saline solutions, and extreme wear.
    Fe/Zn 12 12 um .00048" SC 3 (severe) - Exposure to condensation, perspiration, infrequent rain, and cleaners
    Fe/Zn 8 8 um .00032" SC 2 (moderate) – Exposure to dry indoor atmospheres but subject to occasional condensation, wear, or abrasion
    Fe/Zn 5 5 um .0002" SC 1 (mild) - Exposure to indoor atmospheres with rare condensation and minimum wear or abrasion
    At Professional Plating we are fully committed to meeting your needs for fine quality plating and prompt service.

    We take pride in being both innovative and flexible.
    Last edited by DMC7492; 05-14-2014 at 04:36 PM.

  11. #11
    Senior Member TouchStone's Avatar
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    I wanted to try electroplating my donor carís old parts to give them a new shiny look. After following some various tutorials I found online, http://home.comcast.net/~rt66tbird/w...ncplating.html and http://thefactoryfiveforum.com/showt...t=zinc+plating, I decided to give it a go. I donít intend this to be a tutorial, Iím just sharing my results.
    I wanted to do a test run with some smaller parts before trying this on a larger more expensive part. So I grabbed a bad brake piston, brake bleeder valves and a bolt with a non-removable lock washer. I donít intend on using the bad piston after this replanting attempt no matter how good it looks afterward.

    2014-10-22 19.36.19edit.jpg
    Brake Bleeder Valves

    2014-10-17 22.44.30edit.jpg
    Brake Piston with OEM surface finish and pitting damage

    2014-10-20 00.12.57-.jpg
    Internal Brake piston with light rust on the internal surface

    2014-10-23 00.09.34old.jpg
    Bolt with non-removable lock washer. Covered in grime, old paint, chromate surface finish and rust.

    Cleaning
    I first cleaned these parts in a HCL/Water bath to remove the old plating, paint and rust from these parts. After about 20 minutes I removed and rinsed in clean water to remove all traces of the HCL. Then I let them sit POR-15 Metal Prep for about 15mins. After drying I had clean parts with a dull gray appearance and a rough almost porous feel to them.

    2014-10-22 20.54.50sm.jpg
    Parts after HCL bath and treated with POR-15 Metal Prep

    2014-10-22 20.56.34sm.jpg
    Damaged Brake Piston after removing OEM coating.

    Zinc Plating
    I used the following materials to create a smaller 2 liter batch of electroplating solution.
    Epsom Salt 128 gram
    Zinc Sulfate 43 gram
    White Vinegar 85 ml
    Sugar 27 gram
    Tap Water 1915 ml
    I simply mixed these together until it all dissolved. I used 2 Zinc electrodes and ran this setup with a 6v ac/dc adapter. My millimeter measured that this setup was using about 1.6 Amps. I also tested the current through each electrode and determined that part location greatly affects the current through each electrode, best to leave the part centered.

    2014-10-22 22.03.04edit.jpg

    Following the directions in the tutorials I did 2 15 minute sessions. On the 2nd session I rotated the parts 90degs to even out the coating. After each session I brushed them with a brass wire brush in warm soapy water and then scrubbed them with #0000 steel wool to get the final appearance.

  12. #12
    Senior Member TouchStone's Avatar
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    Results

    As seen in the pictures the parts have a smooth silver appearance which evenly coats the parts. The parts are smooth to the touch. Before brushing with the steel wool the parts have a milky gray look. This can be seen on the low point of the bolt threads where I could not reach with the wool.

    2014-10-23 00.41.44sm.jpg

    2014-10-23 00.07.41rust.jpg
    Places where moderate amounts of rust existed did get coated in zinc but the surface finish is poor due to pitting.

    2014-10-23 00.39.53sm.jpg
    I noticed that the pitting on the brake piston has been softened and can barely be felt when rubbed with a finger or finger nail.

    2014-10-20 00.12.57sm.jpg
    The inside of the piston got a decent amount of coverage despite not having a direct line of sight to the zinc electrode.

    2014-10-23 00.51.19.jpg
    Comparing the OEM piston (left) with my zinc plated piston (right). You can see that the zinc surface finish is not even close to OEM. The texture is not as smooth and light reflection from the camera flash is completely different. The Lego block helps show the differences in reflection. The surface coat on the OEM piston is designed with high tolerances and a very durable surface finish designed for the reliability required for braking. The zinc coating will probably not hold up as well as the OEM as such I would never electroplate any brake piston I plan on using.

    2014-10-23 00.51.09md.jpg
    I am very pleased with results of these tests. Cleaning parts and re-plating them is simple once you have the setup ready, and will make old parts look fantastic.
    Chromating would be the next step as it would increase part durability and to add a bit of color. However the chemicals required are supposedly very nasty and I will probably hold off on this, or opt for a Kit from Caswell. http://www.caswellplating.com/review.../category/256/

  13. #13
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    Nice looking pieces, here are the parts I had professional plating coat. $130 for all donor hardware and the FFR hardware!
    image.jpg and beforeimage.jpg

  14. #14
    Senior Member Hobby Racer's Avatar
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    Quote Originally Posted by JeffS View Post
    The plating solution recipe (which you can scale up or down as you like):
    1 liter of vinegar (5%)
    100 grams Epsom Salt
    120 grams sugar
    8 - 10 square inches of zinc pieces
    Jeff, nice write up! A quick question about your solution recipe though. Does it require any water?

    Most other solutions I have seen on-line call for a significant amount of tap water in the mixture.
    You only list vinegar for the liquid components.

  15. #15
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    Sorry for the 1 year late BUMP. But, this was one of the better DIY zinc plating write ups and commentary I have read and I spent over a month reading many. The examples, after being all buffed out ( i assume) really sold me on plating myself. (since it is my first post here I will also say: I really liked reading about some of your projects. WOW. Talk about commitment. I get frustrated with the cost and time of restoring a Vespa. You guys are hardcore.)

    Can i ask the following?

    1- Why acetic acid/vinegar? Everyone in the DIY world uses it. Aside from being safer and easy to purchase, I can not think of a chemical reason that this is best? Can anyone suggest one? If i wanted to use nitric, hydrochloric or sulfuric would the quality improve? I hate the smell of vinegar. My dentist once looked at my tongue and said "you hate vinegar don't you" I was baffled. He is right. I can small the ketchup when passing a mcdonalds on the highway. I keep my acetic acid bottles in sealed buckets because i HATE the smell. Even if it is in a fume hood i gag.

    2-Why Epsom salt / magnesium sulfate? I can only guess it is to let the current go through the solution and that it is not affecting the plate quality or color. If yes, Why not use an excessive amount of zinc sulfate? Or something that conducts better? Is Mg used because it is less likely to be bound to the zinc plate/crystal? Am i screwing anything up by adding a bunch of Zn sulfate? I only suggest Zinc Sulfate because i am going to add it anyways as it is recommended in most DIY write ups. I am down with using other salts. What do the pros use?

    3- What is the reason that the sugar or karo syrup works? I know everyone says it makes it bright by making the plate even and avoiding large Zn crystal. But how does that happen? Is there a more shelf stable alternative? Sugar tends to support bacteria even in high [Zn]. So I hope to find something i can put in a double contained bucket and leave in the shed until i am ready to plate again.

    thanks in advance for the help,

    I should add that my PhD is in environmental toxicology and a large part of my work is pollution mitigation and policy. So I know how to characterize waste, convert it into safe solid waste and dispose of it via legal methods. Additionally, I am a frequent customer with the local disposal companies. I predict that would be the first warnings offered if one wanted to use HCl and ZnSO4 over vinegar and MgSO4
    Last edited by Cadmus; 11-22-2015 at 05:18 PM.

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    I started with the original formula for the post. I noticed that as soon as I placed the zinc anode into bath it would begin bubbling. Ditto with the plated part after the voltage is removed. Right now I'm at about double the original amount of zinc proscribed. Does this tie with the experience of others?

  17. #17
    Mr. Congeniality mikeinatlanta's Avatar
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    Suggest checking caswell plating. There is also a forum with a lot of good advice.
    https://www.caswellplating.com/#
    MKII "Little Boy". 432CI all aluminum Windsor. .699 solid roller, DA Koni shocks, aluminum IRS, Straight cut dog ring T-5, 13" four piston Brembos, Bogart wheels. BOOM!

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    Johngammel - my limited understanding is that zinc sulfate preloads the solution, reducing the amount of time it would otherwise take the electrolytic process to pull it out of the anode. I had reasonable success with the proscribed solution, though I eventually quit the process since it was taking a lot of time to plate each bolt and nut. I used caro syrup and the result was effective but not pretty. Also, I used 3 swamp cooler anodes and varied the number of anodes based on part size.

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    Will dishwasher salt crystals work in electrolyte instead of Epson salts? As I seem to have lots of it.
    Last edited by RGP; 05-31-2017 at 03:17 AM.

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