In this instructable I show you how I cleaned up bolts that went on my Centuri Tunnel Hunt. The game was stored in a barn for a number of years, and many of the parts on it were horribly rusted during its stay.
In this initial photo you can see just how rusted the bolt is.
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Step 1: Remove That Rust!
In this step I'm using electrolysis to convert/remove the rust that's on the bolt. For more on this process, see my Instructable, Refinishing Metal Arcade Game Parts, Part I. I picked up some scrap sheet metal to use as my sacrificial pieces from a sheet metal fabricator. An arcade game power supply supplies the current.
Step 2: More Prep
After using electrolysis, I took a wire wheel and removed the loosened rust. They've cleaned up very nicely.
The tops of the bolts were rough, so I put them into an electric drill and spun them on a sheet of sandpaper. First a rough grit, and moving up in finer grits until it was smooth.
Step 3: Electroplating!
This is my electroplating step. If I were to leave these bolts as-is, they would rust in very short order. Zinc has long been used as a rust deterrent, plus if you polish it you can get a beautiful mirror finish.
It's pretty simple. I use a 5VDC adapter with the ends cut off. The solution is vinegar. The metal is a sheet of zinc. I got this piece from the same sheet metal fabricator I got the sacrificial piece from step 1. They used to use zinc sheets on slate roofs, so this could be a possible source. I was asked if a galvanized piece of metal would work, but I do not believe there isn't enough zinc present.
I let the piece of zinc sit in the vinegar for about an hour to make sure the solution was saturated with zinc. Then connected the positive terminal of the adapter to the zinc, and an alligator clip clips to the piece to be plated.
Once submerged, bubbles will form by the thousands - that's the water in the vinegar being broken down into hydrogen and oxygen. You can see the piece being plated in zinc very quickly! It should take you mere moments to cover. I plate once, wipe down with a rag and plate again.
You could then take a metal polish (like Brasso) and shine the bolt up to a mirror finish, but I was looking for an original finish, so...
Step 4: Blacken Those Bolts!
...so I used gun bluing to give it the original black finish.
There are two methods of bluing...cold and hot. Cold involves a solution that gets wiped onto the piece. It contains selenium dioxide. Hot bluing involves dangerous temperatures and chemicals, neither of which I wanted to get into in my home.