Restoration Yamaha LS3 1972: Calculating thickness nickel plating

Now the DIY nickel plating is getting better and the plated parts are getting bigger I had to find out what the thickness of the nickel plating would be after a certain time. According to many sources a thickness of 5 micron (0.005 mm) is the minimum to keep the plated part in a nice condition. To give you an idea about thickness; standard aluminium foil is ca. 16 micron (0.016 mm) thick.

Luckily there's a formula to calculate the thickness of the plating; it is based on Faraday's law

T = (I*t*A*10000)/(n*F*rho*S)

Is that all??... no worries mate :)

You don't have to understand how and why, just fill out the numbers for your plating recipe :)

A = atomic weight of the metal in grams per mole.
n = valence of the dissolved metal in solution in equivalents per mole.
F = Faraday's constant in coulombs per equivalent.
rho = density in grams per cubic centimeter.
S = surface area of the plated part in square centimeters.
I = current in coulombs per second.
t = time in seconds.
T = thickness in microns.
in the formula 10,000 is a multiplicative constant to convert centimeters to microns.

Uhh......, OK, most of the needed numbers can be looked up:

Periodic Table of Elements with Valence - Density (rho) - Atomic weight- (right click
on the table and open it in a new window to view it full size 100%)

Nickel with Valence - Density (rho) - Atomic weight

F = 96,485.309 coulombs/equivalent.

A = 58,69 grams per mole (for Nickel)

n = 2 (for Nickel)

rho = 8.908 g/cm3 (for Nickel)
I = depend on the power source you're using. In my case I use a phone charger with a max 350 mA output, and for bigger parts I'm gonna try out a computer adaptor with max 3.4 A output

t = for example 1 minute is 60 seconds, 1 hour is 3600 seconds

S = let's assume the object to be plated is 10 cm long and 10 cm wide => 10*10=100 cm2

If I leave the object for, lets say 2 hours (7200 seconds) in the electrolyte with the 350mA power source, we'll get the following thickness:

T = (0.350*7200*58.69*10000)/(2*96485.309*8.908*100)

T= 8.06 micron

If you wanna plate both sides, simply double the time.

So if I leave it for a bit over 2 hours in the solution it should be thick enough. But if you like to polish allot better go for 10-15 micron.

Another important thing:
To calculate the thickness, use the Current (I) you directly measure in the circuit between the pos (+) and Cathode!!! It will be different then what you read on the charger (which is the max current).

I still had to sand and plate the Yamaha tail light. It was in really bad shape as you can see on the pics.
After a couple of hours it was smooth enough (grit 2000). If you do a really good sanding job it should look almost the same as a plated part. The hardest part was the groove. I couldn't get it super smooth but the tail light is looking way better then before. Another "problem" was that it couldn't be totally dipped in acid because of the mirror bowl. Anyway... after using Faraday's law I choose for a bit over 3 hours plating with the 350 mA phone charger. That should be enough time to give it a thickness of around 15 um.