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DIY Yellow Chromate Zinc Plating


Mark92131

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I promised some details on my attempts to do my own Zinc Plating, figuring "How hard could it be?".  Well, if you have oodles of time like I do, (recently retired), it can be a fun and satisfying part of your restoration journey.  The hardest part is ordering all the supplies and pieces you will need to get the results you want.  I learned some things that should save you time and money if you decide that this process is for you.

 

Supplies

There is a laundry list of things you will need to secure before you are ready to plate.  I will provide links to some of the items I purchased, but feel free to shop for better pricing.

 

  1. DC Power Supply, I ordered mine on Amazon, no longer available, but there are comparable ones for around $50.00
  2. Crock Pot, I ordered one to heat my degreaser before the Zinc bath, but found that cold degreaser works just as well.  This crockpot was 1.5 quart and not appropriate for large parts.  If your wife has a bigger one, buy her a new one and use her old one.
  3. Zinc Anodes, I bought these zinc sheets off of Amazon and cut them to size.  Lots of options on Amazon.
  4. Timer, You can use your Iphone, or buy one of these.  I found that most of the plating process, except for the Zinc bath is under 30 seconds, so one thousand one, one thousand two works good.
  5. Drying Hangers, I have some low steel racks in the garage, so I used these hooks to hang plated parts for drying on the underside of the racks.  You just need space to hang your parts while they dry.
  6. Copper Wire, You need lots of wire to connect your parts to the Negative side of your power supply.  I use 14 Gauge the most, easy to bend, fits into small holes.
  7. Zinc Sulfate Monohydrate, adds Zinc to the Zinc bath, speeds up the process of activating your bath.
  8. Disposable Gloves, keeps the oil on your fingers off of your parts.
  9. Fish Tank Pump, I run a cheap Amazon Fish Tank pump in my Zinc Bath to keep the solution flowing over the part.
  10. Distilled Water, you can't have enough distilled water.  Buy 6 gallons to get started.
  11. Distilled White Vinegar, you need a 1/2 gallon, found in most grocery stores
  12. Epsom Salts, I bought some at WalMart, you will need at least 16 Oz.
  13. Karo Lite Corn Syrup, found in most grocery stores, you will need at least 1/2 cup.
  14. Caswell Zinc Brightener Additive, this makes your Yellow Chromate pop.
  15. Caswell Yellow Chromate, you can get other colors, but Yellow works great, 4 Oz makes 4 Gallons
  16. Buckets, I bought 2 gallon buckets with lids, you will need a minimum of 5.
  17. Muriatic Acid, you don't need a lot, you'll need a 5% solution for etching the fresh zinc part and a bath of full strength for removing the zinc from old parts. I got mine at Home Depot.
  18. Degreaser, you need to degrease your parts before plating.
  19. Spray Bottles, I use distilled water in spray bottles to eliminate the need for rinse buckets.
  20. Tupperware, I used several sizes to degrease and acid strip parts prior to plating.
  21. Copper pipe, I bought a piece of 1/2 inch copper pipe at Home Depot, cut it long enough to stretch over the 2 gallon bucket and flattened the ends with a hammer.
  22. Bench Grinder with Wire Wheel, I had a cheep 6 inch Harbor Freight Bench Grinder and bought a wire wheel for it.
  23. Media Blaster, I bought the Harbor Freight freestanding cabinet during one of their sales, they have a portable one that is pretty reasonable.

 

Preparing the Zinc Bath

Take one of your 2 Gallon buckets and fill it with 1 gallon of distilled water and a half gallon of distilled white vinegar.  Slowly add 1.5 cups of Epsom Salt while stirring until completely dissolved, (you can add more Epsom Salt as long as it dissolves completely).  Slowly add 1/2 cup of Zinc Sulfate Monohydrate while stirring until completely dissolved.  Add 1/2 cup of Karo Corn Syrup and 2 teaspoons of Caswell Zinc Brightener and stir.  You can drop a piece of Zinc in the bottom of the bath and wait a few days until the vinegar dissolves the Zinc into the solution or you can speed up the process by taking a sheet of Zinc, securing it to the inside of the bucket (I cut a 1/2 strip on the side of the sheet with a 1/2 inch remaining on the cut and folded the strip to create a hook over the lip of the bucket).  Attach the Positive and Negative leads from the power supply to the Zinc sheet and immerse it in the bath making sure the power supply leads are above the water line.  Turn on the power supply, dial in 2 Volts, you should see bubbles coming off the Zinc sheet as Zinc molecules are released into the solution.  You can run this until the entire sheet is dissolved.  Turn off the power supply, prepare a new Zinc anode sheet on one side of the bucket, and connect this Zinc sheet to the positive lead on your power supply.  Take the 1/2 inch copper pipe, place this across the top of the bucket and connect it to the negative lead on your power supply and you are now ready to plate.

 

Preparing the Etching Bath

Take a 2 Gallon bucket, fill it with 1.5 gallons of distilled water and slowly add 1.2 cups of Muriatic Acid for a 5% solution.  Take a felt pen and write 5% Muriatic Acid Solution on the Lid and Bucket.

 

Preparing the Yellow Chromate Bath

Take a 2 Gallon Bucket, fill it with 1.5 gallons of distilled water and add the appropriate about of Caswell Yellow Chromate concentrate for 1.5 gallons.  Take a felt pen and write Yellow Chromate on the lid and bucket.

 

Preparing the Yellow Chromate Rinse

Take a 2 Gallon Bucket and fill it with 1.5 gallons of distilled water.  Take a felt pen and write Yellow Chromate Rinse on the lid and bucket.

 

Preparation, Preparation, Preparation

Like painting, plating is 90% preparation.  Here's the steps I use...

 

  1. Take the part that you want to plate and put it in glass bowl or tupperware container filled with enough Muriatic acid to cover the part.  This will strip any old Zinc coating from the part.  When the bubbling stops, carefully remove the part with a plastic spoon and place it in a strainer and rinse with water, blow dry with compressed air.
  2. Media blast the part to remove any rust, scale, etc.
  3. Use the wire wheel on the bench grinder to clean the part until is shines like new.
  4. Take a 10in piece of 14 Gauge Copper Wire and twist it around the part so it makes a solid connection with the least amount of copper wire actually touching the part.  The copper wire prevents the Zinc from bonding with the part, so keep this in mind while securing the part with the wire.  Also consider how the part will drain, you will want solutions to flow off the part.
  5. Set the part aside until you have enough parts prepared to run a reasonable batch.

 

Let's Plate

Take the parts you are going to plate in this batch and place them in a container of degreaser.  If you went the crockpot route, bring the degreaser up to temp and place the parts in the heated solution for 15 minutes before plating.  Instead of having a separate bucket for each rinse step, I use one bucket and a spray bottle filled with distilled water to rinse each part.  Take the first part out of the degreaser, hold it over the bucket and spray it clean using the spray bottle of distilled water.  Put the part in the Zinc Bath about 6 inches from the surface and wrap the end of the 14 Gauge wire around the 1/2 copper pipe, suspending it in the middle of the bucket under the solution.  Check to see if the positive lead is firmly on the Zinc anode plate and the negative lead is firmly on the copper pipe.  Plug in the fish tank pump and secure the discharge air hose so it doesn't hit the part or pop out of the bucket.  Turn on the power supply and set the Amps between 100ma to 1 Amp depending on the surface area of the part (80 - 150ma per Square Inch of surface area).  The Volts will be typically under 2 Volts at that amperage.  The key to this step is there is no set time for the plating process, you need to monitor your part carefully by pulling it up and observing how the process it progressing.  Put on your gloves, if you see that the copper wire is preventing the plating process, move the wire and put it back in the solution.  What you want is an even, bright grey coating of Zinc without dark spots.  The longer you leave it in, the heavier the coating and this will lead to parts that are dull and rough.  The process happens quickly (usually under 2 minutes) so you need to check it constantly and put it out often to check when the part is fully coated and at the peak of bright grey.  When you reach this point, pull it out of the solution and turn off the power supply.  Unwrap the wire from the copper pipe, suspend it over the rinse bucket and spray it with distilled water.

 

Next, open the 5% Muriatic Acid Etch bucket and immerse the part swirling back and forth for no more than 5 seconds.  Immediately pull it out and spray it over the rinse bucket with distilled water.  Put the lid back on the Muriatic Acid Etch Bucket, open the Yellow Chromate Bucket, immerse the part and s l o w l y swirl the part back and forth for a count of 15.  This leaves a "gel" coating of Yellow Chromate on the part, but it is fragile at this step and can be easily scratched or dispersed.  Pull it out on 15, it should be yellow, but not too dark yellow and luminous, not dull.  Carefully dip the piece in the Yellow Chromate Rinse bucket (1.5 Gallons of Distilled Water) for three dips and then hang it up to dry.  You can use a hair dryer or heat gun on low to speed the process of removing the excess water and drying the part.  Wait 24 hours before installing.

 

Conclusions

I have 2 boxes of Fasteners, nuts and bolt, brackets and assorted hardware from several 2002's I have parted.  If I could find a plater that I could ship this hardware in a flat rate box and get it back in yellow chromate at a reasonable price, I would do that.  But for this restoration, it was more the challenge of could I get some reasonable results at a reasonable cost if I was willing to take the time to learn something new.  Mission accomplished.  I hope this writeup helps someone fulfill their DIY dreams.

 

Mark92131

 

 

 

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Edited by Mark92131

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3 Comments


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I did the zinc plating/yellow chromating when we first started making our Ultimate 2002 Side Draft Linkage Systems but had to switch to a commercial plating service when the volume increased dramatically.  

So, I have a very complete plating system with all the components and most of the chemicals needed to get started plating.  I would be happy to sell this at a very good price to an aspiring plater.  Please PM me so we can discuss what you need.

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Hello Hal, I would be interested.

Would you care to talk about it?

Please send your phone # and I will gladly call you back

and we can discuss it.

Typing is a nightmare for me. Old school :)

Kind regards, Alberto

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