Prince George Vintage Motorcycle Club
General Category => General Discussion => Topic started by: stevecrout on January 15, 2021, 06:24:05 PM
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That's right folks. Nothing to do with using the right fork or holding your pinkie while sipping that chardonnay.
Electroplating as Part of the Restoration Process
Once you start down the road of plating your own stuff be prepared for the myriad of opinions and options available on what to do and not. I started thinking about plating a few years back and in preparation I purchased a good variable power supply to manage my milliamps. It was a good $75 investment as I’ve used it for a number of other tasks. Lots of the other stock is available in your kitchen or local hardware store. Caswell Plating has all the stuff you’ll ever need and some great reference pages too but the kits are expensive and if you only have a few bits to do it might not be worth the work. On the other hand, I can imagine this process would make an interesting ‘Garage Night’ exercise where a few people could bring one or two items to try it out and pitch in a few dollars to help offset costs.
Supplies
I figured I should start simple and so I decided to give zinc coating a try. After sorting through all the information I came across in my research, I ended up with this list of stuff to procure:
- A supply of zinc strip – the Rona or Home Depot rolls are about 95% pure.
- An adjustable power supply that can deliver 0.5 volts up to 12 or so and from .10 mA up to 10 amps Although you can get away with a smaller unit and take longer to plate it is nice to be able to adjust the amperage when needed. Here’s a bit more information on what to look for - https://emeraldcoatings.com/wp-content/uploads/2014/12/Power-supply-info.pdf
- 5% acidity white vinegar – 4 liters
- A bag of Epsom salts (not the perfumed rosy coloured stuff you use for your soak in the tub!) white will do.
- A small bottle of corn syrup – used to promote the shine or brightening quality of the plating. You can also use white refined sugar but the glucose in the corn syrup is supposed to give an even better shine.
- 1 or 2 / 5 gallon pails to store the electrolyte and one about 2 – 3 gal for the actual plating or even smaller, down to about a gallon/3.85 litres
- Digital kitchen scale
- Aquarium heater up to 30 degrees and probably 1500 watts at a minimum
- Acetone for parts cleaning or TSP solution
- Nitrile gloves for parts handling
- Pair of all metal kitchen tongs
- About 18” of ½ “ copper tubing with several copper wire hangers solidly attached ( They have to conduct electricity through to the anodes/parts) See Photo
- A wire wheel using medium gauge wire
One of the popular sites suggests each liter of the electrolyte solution should use these ratios:
- 1 liter of vinegar
- 100 grams of Epsom salts
- 120 grams of syrup
- 200% of the area of your parts as zinc cathode sizes
Cleaning Your Parts
Before we get mixing and expecting great results – something to keep in mind is to treat the parts as though they were going to be used as eating utensils. That’s how clean they need to be! A process of degreasing, wire wheel and a bath of acetone or TSP should leave your parts in good shape. Only use the clean, metal tongs or gloved hands to handle them after that. You’ll soon see if there is any grease or fingerprints left on the parts as the plating skirts around the stains and leaves a mess.
Calculating Surface Area and Time/Current Required
Next we need to calculate the amount of active plating time to allow and this depends upon the area of plating surface to be taken on. A couple of things to keep in mind are the amount of current required rises exponentially with the area to be plated and the amount of time it will take is dependent upon the amperage used the temperature of the solution and the thickness of the plating and the ability of the electrolyte solution to pass the molecules from cathode to anode. I’ll insert some tables I’ve run across or made and add some pertinent web site material that should help in figuring this out. Lots of things to consider when doing these calculations including the surface area of a bolt for example. The pitch of the threads on the bolt add as much as 40% to the total area of the cylinder to be plated along with the head surface and side areas so it’s best to use the calculators found at the Caswell site shown below.
The recommended starting voltage should be 65 mA per sq inch so it’s important to accurately measure the total area to be plated. Use the following site to calculate your parts then decide how much you want to try to do at one go. https://caswellplating.com/surface.html
Smaller batches equal faster finish times and it gives you a chance to try out some of the variables a bit. Recording your voltage and amperage and area sizes for each batch will show some trends that you can adjust according to the outcomes. For example, if the finished product is dull or frosted looking the voltage is too low and if the voltage is too high the edges will look uneven. Violent bubbling is great in the hot tub and when you’re cooking your oatmeal but not in the plating solution and it means the voltage is too high. There should be a very slight amount of bubbling during the process. Have a look at this Caswell site to help determine time and current - https://www.caswellcanada.ca/Rectifier-Selection-Tool.html
Getting Started
When you’re ready to give it a try fill the container you will use with electrolyte and start heating your solution so it is as warm as the aquarium heater can make it. Some experts call for 60 degrees as the ideal temp but maintaining this is difficult without a heavy duty heater. I’m using the 150 W aquarium heater and expect to get up around 30 degrees.
Then go over all the parts and ensure they are fanatically, kissable clean.
There’s quite a few opinions on how to finish cleaning the grease off. Some use Acetone and others use a bath of TSP / Trisodium Phosphate. You’ll soon find out if your chosen method is a good one by the finished results. One way to check for clean is the way water will act on a surface. If it bubbles up through surface tension you know there is still grease present. If it seems to run off flat in all directions then you are probably good to go. Have a look here - https://emeraldcoatings.com/wp-content/uploads/2018/03/waterbreak-test-canada.pdf
Now you can cut your zinc strip into at least 2 parts of at least 200% the size of the area you are going to plate. So your 2” x 3” part is 6 sq inches times 2 or 12 sq inches so your 2 zinc strip cathodes should be 12 sq inches each. Place them on opposite sides of the pail and connect them to your negative side of the power supply.
Next is the process of attaching your items to the hanger and the best thing to remember is to ensure there is conductivity at every joint or connection. Poor connections will raise resistance and your calculations for necessary voltage will be out of whack. The hanger will be connected to the positive side of the power supply. (No, just because they’re British parts it doesn’t mean they connect up the opposite way)
Remember to take your parts out every 10 – 20 minutes and give them a scuffing with a scotch-brite pad to keep the surface area clean and available. The resulting finish should be fairly bright. If not, crank the voltage up a bit. You can run them for another 1 or 2 sessions until you are happy with the finish. Here you can see the purpose of adding sugar or corn syrup to the mix. The sugar keeps the zinc crystals in alignment during the process and prevents the larger zinc crystals from taking over and attaching too quickly, leaving a rougher surface as a result.
Finishing Off
When the process is complete, remove the bits and give them a wash in clean, distilled water before rubbing the final dullness off with the scotch-brite pad. A brass brush will work well on threaded or other hard to get at areas. Once the part is cleaned and dry you can also opt to use a chromate bath that will ‘lock in’ the zinc coating a bit better. The chromate bath kit is available from Caswell Plating.
I'll put in some photos of before and after when I have the parts ready to go on Saturday.
Next – I want to try anodizing and since I have most of the supplies I’ll need it should be an easier set-up.
What did the copper anode say to the aluminum cathode, prior to electroplating? Al Cu later.
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So Saturday came and we mixed up a batch of electrolyte using the following:
- 1 litre of vinegar
- 100 grams of Epsom salts
- 120 grams of syrup
- 4.5 litres of water
and prepped these parts for plating:
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Next we worked out the total area for the parts (4 pieces) then stuck them on the wire and made sure they were completely submerged, Warmed the water up to about 30 degrees, applied the power - 1.7 amps and 2.5 volts.
You can see from the second photo that we have the right sort of fizzing action and there is a definite transfer going on.
We left it for 40 minutes.
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Now the process should have transferred about 0.001" of material to the parts.
Lets have a look!
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Well - that wasn't the result I was hoping for.
Even after scrubbing the surface with the scotchbrite pad it was still dull and patchy.
Time to take a look at the troubleshooting sheet.
Could be too much current as it fits the "Dark Grey" outcome. I think this is going to be a normal thing for this sort of a process. There's so many different combinations of directions out there. Current and cleanliness seem to be the big ones.
Oh well! Try it again in a few days and will keep you all posted.