Metal plating percentages

[Manoet]

Started the morning running an M3X.5mm bottoming tap thru the ultrasonic cleaner to get it as squeaky clean as possible with no other metal contaminants remaining on it. Then ran it in & out several times in each of the 4 outer threaded bores that hold the bottom cover to the upper case. Carefully brushed all the metallic particles from the tap with a previously sealed/sterile toothbrush opened specifically for this sample collection after each in/out pass in the threaded pilot bores on to a clean paper towel. Then headed out to the anodizers who use a spectral analyzer litmus test for testing the presence of various metals and tells them if anodizing will work before they commit to a job. It will confirm with great accuracy the metal content of small flakes further ground in a glass mortar/pestle with the drop of a liquid agent on to the ground flaked powder collected from the screw holes then under the spectroanalyzer compare the color against a series of colored squares comparing metal ratios from 16.3 million options. Accuracies within 1%. There's a more accurate one available but samples have to be sent out-of-state and can go down to .0005% accuracy. For my purposes this is way better than I hoped to find and walk-in service to boot. Then he wouldn't take any money saying bring me the work if you end up doing this. I handed him $20 and told him its a definite 'maybe.'

The breakdown of our plating was a surprise to me as it turns out there are 4, not 3 layers as I originally thought since 3 is the minimum for aluminum. Turns out we also have a layer of tin under what I thought was the bottom copper plating.

The breakdown by metal and percentage is as follows:

Tin 21% paramagnetic (lightly magnetic)

Copper 16% non-magnetic (mostly) see link: https://www.youtube.com/watch?v=E97CYWlALEs

Nickel 28% Ferromagnetic (highly magnetic/can be magnetized)

Chrome 33% (a weird one indeed) totally non-magnetic at below 38*C/104*F but paramagnetic above that temp. Only elemental solid on the planet with this characteristic!

Bauxite 1% non-magnetic (the primary ore in aluminum)

Undetermined 1%

[Manoet]

To clear up a possible misconception the above testing is not an indication of percentage or thickness of each metal plating element layer used. In other words there isn't necessarily over twice as much chrome as copper plating used or twice the layer thickness of chrome compared to copper. The percentage of various metal elements in this procedure is determined by particulate matter collected in the tap's threading. Naturally it will cut and gather more plating particulates closer to the surface of the threads in the Devialet and less as it cuts deeper into the threads due to thread cutting taper in the tap. So it's entirely normal for trace metal element percentages to be in higher percentages in inverse order from bottom-to-top. But its an empirical indicator that there's 4 plating layers including tin rather than the originally thought of three, ie; copper, nickel & chrome which is the minimum plating layers required to plate aluminum. Actual individual plating layer thicknesses/percentages is anyone's guess and due to each sacrificial metal's tank submersion times and solution temps can easily vary from one part to the next even on parts done simultaneously within the same tank.