Copper content in brass-top coils

[namdc3]

I have a question for the coil experts out there. Different brass-top coils seem to have different copper contents in the brass. Was this a change that was distinctly made based on a date, or was it random or vendor based? Some look to be very high copper content, but I assume that they are still some form of brass. I think this is called red brass, but I’m wondering why there are such distinct differences and if there was a design change.

[namdc3]

Here’s some discussion but no conclusion as of 10 years ago.

https://www.mtfca.com/discus/messages/5 ... 1424193693

[Wayne Sheldon]

I "think" that the prevailing opinion today is that the "brass" top coils were originally some blackened treatment on the metal tops. That treatment apparently did not last very long, and by the time the coils were ten years old, most of them had very little if any of the blackening left. More recent discussions (less than ten years ago?) have speculated on what sort of chemical treatment resulted in the original flat black appearance of the metal tops. Whatever it was, it faded away. I have only seen a handful of original tops with any sign of the original blackening remaining to be seen, even looking very closely.
Ford probably did not care whether the "brass" under the blackening was reddish or bright brass. I would guess that when the cars left the factory or dealers showroom, sometimes they might have all matched? (Matching batches from one supplier?) However, I would imagine that a lot of times, many cars, the coils were not all matching colors under the blackening.

As beautiful as the polished brass tops are? With the metal tops painted flat black they look pretty sharp also.

[Dan Hatch]

I think if you read the last post on that earlier thread you will find the answer.
John R says what is the most likely answer.
These coil came out around 1914. There was something going on in Europe that would cause brass to get cheap for coils. IE red brass to replace good brass. Then no metal tops at all.
It was called “The Great War” till the Germans changed the name to WW1.

[Ron Patterson]

Both red and yellow brass are alloys of the same metals (copper & zinc). But what sets them apart is the quantity of those metals. For example, red metal comprises 80-85% copper and 5% zinc. Conversely, yellow brass includes 60-70% copper and 30-40% zinc.
Ron Patterson