I thought I would bring up the topic of brass, can be a bit confusing, by no means do I have all the answers nor did I pay much attention in science class.
Why do we use brass in clocks? Low friction, high corrosion resistance and high tensile strength.
Brass is made up of a combination of copper (Cu) and zinc (Zn). Depending on the percentage of copper and zinc determines brasses properties and application. Now, to make it a bit more confusing, lead (Pb), (usually somewhere around 1-3%, can be introduced to the alloy for machine-ability purposes).
Reading about types of brass in some of our horological books I have found references to a brass that I did not find in the USA. Looking into it a bit further I realized the #'s refer to types of brasses found on the European side of the world, numbers like CZ121 or CZ120 ect...
Here is a bit of what I am finding;
CZ120 = 59% copper, 39% zinc, 2% lead
CZ121 = 58% copper, 39% zinc, 3% lead
Now, over here in the US I see #s like C360 or UNS C36000, C260 or UNS C26000, C385 or UNS C38500.
Here is a bit of what I am finding comparable to the CZ brasses;
UNS C360 = 60% copper, 37% zinc, 3% lead
UNS C377 = 58%-60% copper, 39% zinc, 1.5%-2.5% lead
UNS C385 = 58% copper, 39% zinc, 3% lead
Color of a brass may also be a determining factor of what to use especially when doing a restoration on a older clock
(wanting it to blend in) The term "yellow brass" from what I understand is an American term that refers to a typical 33% zinc brass.
O.K. thats a start, to mention other brasses we still have CZ124, c35300(engravers brass) to look at...and there are so many more..
Here is a question....how can you find out what type of brass you may have when you do not know for sure what type it is?
...if you have any input or experience with brass let us know.