John D. Bartleson Jr. wrote:
> Interesting Pete, When you scrape a copper fuse plug is it like a new penny beneath?
Yes ...or very close. I'll talk about the various metal-colors further down in this post.
> I think brass is a mix of copper with about 5% plus of zinc.
No. The copper-content ratio you indicated in your statement (95% copper, 5% zinc) is what was in a US penny until 1982. I'm sure you wouldn't say those pennies were made of brass. ;-)
Nearly four decades ago, when trying to riddle out the differences I saw between US-made and CS-made Bormann fuzes, I got to wondering about why some types of fuzes corrode like crazy and others corrode much less, if at all. (Also, why do some metal sabots "stretch" nicely when under stress, while others rip, and others shatter like a china dinnerplate?) I found the answer was in the "content" of the metal. In my decades of studying to figure out the actual metal content of civil war projectile sabots and fuzes, I've had to do a fair amount of basic-level Metallurgical study.
For readers who don't already know the Metallurgical facts, here is a simplified explanation of brass, and its various colors.
Brass is an alloy of copper and zinc. Strangely, when you combine (let's say) 2 ounces of that "pink" metal with 1 ounce of that silvery metal together in the melting-pot, the result is a very different color than either of those metals. The 65/35 copper-&-zinc alloy is "yellowish" ...which with the addition of greater and greater amounts of copper, becomes golden, then orange, and then a reddish hue I would describe as a "light" pink.
The following percentages are approximations, not super-precise. (I've found that various Metallurgical charts disagree with each other about the percentages.)
50-60% copper, remainder zinc, makes "white" brass
60-75% copper, remainder zinc, makes "yellow" brass
75-80% copper, remainder zinc, makes "golden" brass
80-85% copper, remainder zinc, makes "orange" brass,
85-90% copper, remainder zinc, makes "red" brass
Note:
"Red brass," being extremely high in copper content, is very nearly indistinguishable to the eye from copper, so please guys, let's not argue about whether a fuze is made of copper or what a Metallurgist would call "red brass."
> I would have thought they would use brass which is harder than copper.
Yes, brass is harder than copper, because the zinc in the brass is a harder metal than copper. The hardness becomes important if the fuze's metal needs to be hard because it will put to "violent" stress. For example, the fine-gauge threading on a Percussion fuze's anvil-cap needs to be strong enough to not fail when the fuze's slider violently strikes the anvil-cap. Also, a Watercap fuze's fine-threaded small central insert needs to be able to withstand firing-blast without getting blown down into the fuze's body. So, the Confederates needed to use brass for their Percussion and Watercap fuzes. But CS simple timefuze adapter-plugs (which do not have "fine" threading) did not need to be made of brass. So, if you've got plenty of copper but zinc (required for making brass) has become scarce in your nation, your fuzes and sabots will be copper unless the use of brass is a serious necessity.
Closing note:
I've observed that a (very) few CS timefuze adapter-plugs are made of brass. I think the explanation is that usually (but not quite always) there was something "special" about the brass CS ones. For example, their threading was different than the usual CS standard of 12 threads-per-inch, or the body was a non-typical diameter for CS shells, or it was a fuzeplug for a non-typical Confederate-made projectile like a cylindrical Case-Shot. Perhaps brass was used as a way to visually "alert" the artillerymen that the fuzeplug was not the typical version. For example, I dug a "groundburst" British-made Long-model Whitworth shell near Richmond VA. When I examined the CS-made timefuze adapter-plug I dug in the hole with the frags, the fuzeplug was made of brass, and was 1.1-inch wide, to correctly fit that British-made shell's fuzehole. Also, the very rare CS extra-long-range rifled Case-Shot fuzeplugs that I've checked are made of brass.
Regards,
Pete