Is there a surefire way to tell if a cap is brass or bronze? I've always just called everything a brass cap, but it seems that some might actually be bronze. How would you know?
There's some overlap between brasses and bronzes, but basically brass is copper and zinc, while bronze is copper and tin. They can be hard to tell apart unless you're machining them.
I'm told that if you swab brass with hydrochloric acid it'll look red like copper due to the surface zinc being swabbed away, but who carries hydrochloric acid with them?
Jim Frame, post: 421262, member: 10 wrote: I'm told that if you swab brass with hydrochloric acid it'll look red like copper due to the surface zinc being swabbed away, but who carries hydrochloric acid with them?
Everyone, but accessing it in public can be socially awkward 😉
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Jim Frame, post: 421262, member: 10 wrote: There's some overlap between brasses and bronzes, but basically brass is copper and zinc, while bronze is copper and tin. They can be hard to tell apart unless you're machining them.
I'm told that if you swab brass with hydrochloric acid it'll look red like copper due to the surface zinc being swabbed away, but who carries hydrochloric acid with them?
Seems like I saw something where lemon juice would also work, but probably not as good as hydrochloric.
Heh-heh, just throw up on the cap and swab it!
Now now, it may not be a cap, it may be a disk or even a plug. 😉
Jim Frame, post: 421262, member: 10 wrote: .... but who carries hydrochloric acid with them?
Geologists. They often carry a small bottle to test for limestone.
Brass looks more refined than bronze.
I have two 3/4 inch valves that are approved for 600 psi.
The brass is half the thickness of the bronze.
0.02
Mark Mayer, post: 421297, member: 424 wrote: Geologists. They often carry a small bottle to test for limestone.
Never trust anyone with a large supply of acid (or a shark tank in their secret underground comand post), most likely they're a Bond villain.
Fortunately calling a bronze disc a brass cap usually isn't source of confusion.
I think brass is yellower, and bronze could pass for gold. I scratch the disc with a knife. Higher copper redder tone. I think bronze is softer.
If I recall the order correctly, bronze is harder than brass and will scratch brass. So either carry a small piece of both and perform the scratch test. Or carry along your handy Rockwell hardness test kit.
Allen Wrench, post: 421259, member: 6172 wrote: Is there a surefire way to tell if a cap is brass or bronze? I've always just called everything a brass cap, but it seems that some might actually be bronze. How would you know?
Twenty years ago, when we got the last shipments of "caps" at the highway department from Bernsten they were bronze, and had been for a while. But brass and bronze are almost indistinguishable because of the number of different types that are manufactured. There is yellow bronze, and red brass. From lugging tote sacks each with 50 monuments I can tell you the slightly lighter weight bronze isn't that much lighter.
This chart might give you some sort of idea as to the gray area between the two:
http://www.metalreference.com/Forms_Copper_Alloy.html
ps -most all of Bernsten's "caps" are bronze.
Previous threads on subject
https://surveyorconnect.com/community/threads/terminology-brass-cap-vs-brass-disk.328682/
https://surveyorconnect.com/community/threads/brass-cap-v-brass-disk.309461/
Jim Frame, post: 421262, member: 10 wrote: There's some overlap between brasses and bronzes, but basically brass is copper and zinc, while bronze is copper and tin. They can be hard to tell apart unless you're machining them.
I'm told that if you swab brass with hydrochloric acid it'll look red like copper due to the surface zinc being swabbed away, but who carries hydrochloric acid with them?
Everyone does. You just really don't want to access it. It is in your stomach.
Bronze is more expensive and surveyors are cheap. 😉
Jim Frame, post: 421262, member: 10 wrote: but who carries hydrochloric acid with them?
Anyone with a car or truck that has a lead-acid battery. Pry the caps off and use a q-tip swab to get some.
Car batt uses sulphuric. Not interchangeable.