I was originally going to fabricate the manifold from stainless steel so I'd have it in white metal. In hindsight, that would have been madness. Ron's version in brass got me thinking about nickel plating - something I've been wanting to try for some time. There are a lot Youtube videos on DIY plating, and the one by Doc1955 who occasionally posts on this forum is as good as any.
Plating requires an electrolyte, a low voltage dc source, and a pure nickel anode (all available from Amazon). The most commonly used electrolyte can be made by dissolving a couple online-available nickel salt chemicals in water (a.k.a. Watt's solution), but another (nickel acetate) can be made from ordinary kitchen ingredients i.e. plain white vinegar and salt.
Also available is a Watt's-based kit from Caswell that contains nearly everything needed. An advantage of this fairly expensive option is that it will also include some proprietary chemicals for a bright finish right out of plating solution.
Unfortunately, I wasn't able to find any end result comparisons. Nickel acetate doesn't seem to be commercially popular - maybe because of an incompatibility with the industry's 'secret sauce' brightening agents. I initially experimented with nickel acetate since I already had everything needed on hand. My test parts turned out so well that I continued on with it.
The first step was to make the lead acetate. This involved adding table salt to 1-1/2 quarts of white vinegar in a wide mouth canning jar. The electrolyte can be used over and over (it even gets better with use), and so I used a jar with a spring lock top that I'll use for both plating and electrolyte storage. A pair of pure nickel anodes (purchased from Amazon) was then lowered into the vinegar, and 5 VDC from a wall wart power supply was applied across them.
I found little guidance on how much salt to use, and my three tablespoons turned out to be more than was evidently used in any of the videos. The salt will control the conductivity of the electrolyte which in turn will affect the speed and (maybe) the quality of the plating. In this first step, a solution of nickel ions is being created for later use in the actual plating process. Over time, the color of the solution will turn greenish-blue indicating that it's ready for use. How fast this happens will also depend upon the salinity of the solution. In the videos that included current measurements, tens of milliamps through the solution was common, and the electrolyte creation process took overnight. My own measurement indicated 2.8 amps, and my electrolyte appeared ready for use in about an hour.
Although my DC supply was capable of even more, the relatively high current draw was concerning. Everything I'd read indicated best plating results will be obtained while using low currents. These sources were referring to Watt's electrolyte, though, and so I wasn't sure if the same applied to nickel acetate. I decided to continue on.
The part to be plated is connected to the negative terminal of the supply, and one or more nickel anodes are connected to the positive terminal. Hydrogen bubbles immediately begin forming around the part, and in my case they temporarily fogged the solution. The bubbles tend to agitate the electrolyte making additional stirring unnecessary. Plating occurs quickly - in just a few minutes. Other than pulling the part up for inspection, it's difficult to judge when you're done.
Thicker plating will likely result from longer plating times, but quality nickel plating is measured in tens of microns even in plating shops. I suspect, with no evidence to back it up, that if very long times were attempted, a rough uneven finish might result from second order effects related to the shape of the part with respect to the shape of the electrode. The wire hanger used to hang my parts built up an ugly rough finish rather quickly.
The importance of proper surface preparation is stressed in any reference on plating. Even when done commercially, nickel plating isn't thick enough to fill in machining marks or surface scratches. Except for its color, a part's surface will look the same after plating as it did before plating. The part also needs to be absolutely free of any oil or grease including finger prints.
I finished all my parts with 1000g paper and a white Scotch-Brite pad while supported on a fixture to avoid finger prints. Most of the manifold's metal finishing was done while the tubes were on the lathe and still straight. Its soldering fixture was used to hold the completed manifold during final polishing. I found I got better results if the final polishing was done immediately before plating rather than over a tarnished surface. All parts were dip cleaned in acetone, air-blown dry, and then hung in the plating solution without being touched by hand.
The 2-3 minute plating time on all my test parts looked great. A couple soldered flanges using both 60/40 and nearly pure tin solder took nickel plating well. When removed from the electrolyte, all parts had a smooth gray satin finish which would be suitable for some applications. They might have had a brighter finish if the Caswell kit with its secret brighteners had been used.
For the manifold, I wanted something that looked like chrome. Even the brightest nickel finish, though, has a slight yellow tinge compared with chrome. Using red rouge buffing compound on a strip of micro-fiber cloth, I was able to buff its surface to a bright reflective finish that was close enough. - Terry
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