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Brass differences ???

Posted: Sat Feb 07, 2026 11:06 am
by up148
I thought this was interesting so it gets its own thread. I just stripped (again) the paint off the USH FEF and 3rd Rail Z5 shells. I used the PVC soaking chamber method, so they stayed submerged in the pasty Max Strip for 12 to 24 hours, with the Z5 soaking the longest (harder paint).

So, the big question is what does this discoloration of the brass shells tell me (if anything)? Is the 1960's alloy "better" quality or contain more copper or zinc than the 2012 brass used in the Z5?

The discoloration doesn't bother me, as the Z5 is just a donor shell to scavenge whatever detail parts I can for the FEF project........and there will be a lot. Too bad the Z5 perforated running boards aren't as wide as the FEF3's.

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Re: Brass differences ???

Posted: Sat Feb 07, 2026 11:37 am
by bob turner
https://en.wikipedia.org/wiki/Brass

If you wind up with no use for the forward sand dome, think of my Erie Berk project.

For me, the strength of the boiler shell (or cab, or tender sides) is what's important. I use more or less standard yellow alloy, but always slightly thicker than imports (.032 min for boilers, .020 for sheets).

Re: Brass differences ???

Posted: Sat Feb 07, 2026 12:28 pm
by Rufus T. Firefly
up148 wrote:So, the big question is what does this discoloration of the brass shells tell me (if anything)? Is the 1960's alloy "better" quality or contain more copper or zinc than the 2012 brass used in the Z5?


While "brass" is generally a 2:1 copper:zinc alloy, there are probably a lengthy list of variations from that ratio and then processing in sheet brass.

Re: Brass differences ???

Posted: Sat Feb 07, 2026 1:30 pm
by up148
I figured it was a different % of ingredients in the alloy used by 3rd Rail and the Chinese, compared to what was used back in the 60's by KTM/Japan.

I mic'd the thickness of both shells in several areas and both are in the .030 to .032 range, which I thought was a feather in the cap for 3rd Rail. I remember my Korean built models were less when I mic'd them back in the day, but I can't remember the numbers now.

The dome is yours Bob. I should start "de-manufacturing" it next week. BTW, that is a label the FAA put on the aircraft salvaging process. :lol: :lol: :lol: :lol:

Re: Brass differences ???

Posted: Sat Feb 07, 2026 1:35 pm
by bob turner
Don't forget to check on my Wiki link. Lots of info on color, strength, corrosion, etc.

Thanks! If Stevenson finds the exact dome first I will let you know.

Sunset/3rd Rail used .030 for boilers (except for the SP Atlantic and Consolidation). USH used about the same thickness, but PSC (at least their AC-6, which I had for a while) used .020. Wimpy. Lobaugh was in the .040-.050 range, but fireboxes were .016.