Clean or Leave alone

[Bindlestiff]

May I suggest that before you put them in vinegar that you test the process out on a penny or a scrap piece of copper or brass. That process may not yield what you expect.

If it is simply dirt that you want to remove, so you can tell its old brass but with an aged look, maybe a mild soap or glass cleaner will give the results you want; again - test on something disposable first.

I don't know what look you want but I have used vinegar on pennies when I was young and it will remove the dirt & grime AND any old patina as well. It will make it shine but without the high gloss a polish would give it. It doesn't look old when its done.