At this shop we handle small plating orders as if they were unstable nuclear warheads. This is because we understand the importance of every piece in the batch. Not all platers are this patient. We know that the only thing worse than reading a bunch of stuff you already know is losing rare parts and stalling your project. This is not rocket science, but if I didn’t see a potential disaster every other day I wouldn’t be writing about it. I’d be doing something fun, like sorting bolts. If you don’t have time to read this now, bookmark the page and read it later. No matter where you take your parts for electroplating, this info will help you.
Do your best to separate types of metal before electroplating
Automotive, motorcycle and other machine parts that are zinc or cadmium plated are typically ferrous metals, meaning they contain iron i.e. steel. This means they are magnetic. For $20 you can buy a powerful magnet from your favourite hardware store. You should buy one.
If nonferrous metals sneak into the mix, this can be a problem. So we are going to separate them out.
Spread your parts out over your workbench. If your workbench looks like my workbench, you will probably need to use your dining room table. Put a towel over the table so your woman doesn’t kill you. If you don’t have a woman, put the towel over the table anyway.
Now hover over your parts with the magnet – wow, magic. Put all the steel you picked up with the magnet into a container. It’s time to separate the aluminum, stainless steel, brass, copper, and zinc castings that are still sitting on your table.
Electroplating Nonferrous Metal
Copper and brass are perfectly suitable substrates for cadmium, zinc and tin plating. The problem is they are softer than steel. If your parts are going to be barrel plated it means they could end up tumbling in the same barrel as your harder, heavier steel parts. If the softer metal is threaded or tubular, like threaded bolts or a fuel line, there is potential for damage.
So how do you separate brass and copper from stainless, aluminum and zinc castings? Colour is the most obvious answer. However, maybe your parts are caked in old grease, or they have old plating covering them. It’s still really easy. Copper, brass and stainless steel will feel as heavy as you’d expect when you pick them up. Aluminum and zinc castings will feel like they are made of feathers in comparison. Go ahead and put your copper, brass and stainless steel in another container.
Now we arrive at the most crucial point in your metal separation journey. This is why we just ruined a perfectly good towel and made a mess of your dining room. The cleaning process that occurs prior to plating uses heavily caustic and acidic solutions. The industrial strength cleaners that remove oil and grit from your metal components will dissolve aluminum. The hydrochloric acid that is used to neutralize the cleaners and remove rust will dissolve zinc castings. So please, don’t hand a plater a bucket of parts and say “here plate this” unless you are sure that you have identified any aluminum or zinc castings.
Zinc castings can be electroplated, they just need to be cleaned a little differently. Point the casting out to your plater. Aluminum is not typically electroplated, and chances are it got mixed in with your parts accidentally. If your plater has an Alodine or aluminum chemical conversion line operating, you can discuss an etch cleaning and passivation process with them. Or just pull the aluminum out and pretend this never happened.
I guarantee your plater is not going to sort your metal for you. But if you care enough to sort your parts, your metal will get the attention it deserves and you will greatly reduce the chances of your parts being lost or damaged.
Separate & Package Tiny Metal Components
If you’re working on a restoration, or you’re a manufacturer and you’ve decided to save a few bucks by mixing your metal parts and having them processed together, remember that you know your components better than your plater does. Mixing parts in a plating barrel can save time and money under the right circumstances. It can also turn into a nightmare if your plater is inexperienced, or if they don’t know what parts are in the barrel.
Motorcycle projects with a carburetor rebuild in the mix are the jobs that worry me the most. I’m not a mechanic, but when I see a bucket of bike parts the first thing I do is go digging for those tiny carburetor screws. Here’s why:
Plating barrels come with different features and configurations. When parts are mixed we use our judgement to select the barrel most suited for your order. The easiest example I can use to illustrate this is drainage hole size. This particular customer included some very tiny cotter pins in a large bucket of medium-sized bolts.
I had no idea they were in the bucket but I dug through it just to make sure. Most platers will not do this and I don’t blame them. The barrel I wanted to use had medium-sized drainage holes. Had I used this barrel, the pins would’ve fallen through the holes and been lost.
They are just cotter pins, so it wouldn’t have been the end of the world. But you can see how this would be a disaster if tiny, rare fasteners were mixed in with a hundred pounds of larger parts. What is the solution to this problem? Use a barrel with smaller holes. However, not all plating companies have properly sized barrels for small plating batches with tiny components. If your plater can clearly see the variety of components in your order and they don’t have a barrel that can accommodate your small parts, they have two options. They can decline the work, or they can wire up the smaller items and process them with a rack line.
Other Ways To Lose Small Parts During Electroplating
- your fastener bounces out of the barrel as it’s being loaded with the larger items
- your clip gets lodged in a drain hole or a dangler port without being noticed, then ends up mixed in with the next order that gets thrown in that barrel
- your pin skips off the landing pad as the barrel is dumped after plating
- your rivet flies out of the basket as it spins in an industrial dryer
- your spring gets lodged in a drying basket and then mixed in with the next order
- your eyelet bounces off the packaging table when the basket is dumped after drying
- your carburetor screw doesn’t make it back into your box because a worker is quickly packaging your larger components without noticing it
- your nut becomes lodged inside the hollow of another larger part that should not have accompanied it into barrel in the first place
At the end of the day, it’s common sense. Small things are easy to lose. Your plater can’t be careful with your small parts without knowing they’re there in the first place. Give your small parts the attention they deserve. Point them out. Package them separately. The devil is always in the details. That’s why you love restorations, right?